Co-reporter:Madison L. McCrea-Hendrick, Shuai Wang, Kelly L. Gullett, James C. Fettinger, and Philip P. Power
Organometallics October 9, 2017 Volume 36(Issue 19) pp:3799-3799
Publication Date(Web):September 18, 2017
DOI:10.1021/acs.organomet.7b00570
The reactions of the aryl tin(II) hydrides {AriPr6Sn(μ-H)}2 (AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) and {AriPr4Sn(μ-H)}2 (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) with aryl alkynes were investigated. Reaction of {AriPr6Sn(μ-H)}2 and {AriPr4Sn(μ-H)}2 with 2 equiv of diphenyl acetylene, PhCCPh, afforded the aryl alkenyl stannylenes AriPr6SnC(Ph)C(H)Ph (1) and AriPr4SnC(Ph)C(H)Ph (2). In contrast, the analogous reactions of {AriPr6Sn(μ-H)}2 with 2 equiv of phenyl acetylene, HCCPh, afforded a high yield of the cis-1,2 addition product AriPr6(H)SnC(H)C(Ph)Sn(H)AriPr6 (3), which has a four-membered Sn2C2 core structure comprised of two Sn–Sn bonded Sn(H)AriPr6 units bridged by a −C(H)═C(Ph)– moiety. The corresponding reaction of the less bulky hydride {AriPr4Sn(μ-H)}2 with 2 equiv of phenyl acetylene leads to AriPr4SnC(H)C(Ph)Sn(H)2AriPr4 (4) which unlike 3 has no Sn–Sn bonding. Instead, the tin atoms are connected solely by a −C(H)═C(Ph)– moiety. Each tin atom carries a AriPr4 substituent but one is also substituted by two hydrogens. The difference in behavior between PhCCPh and HCCPh is attributed mainly to the difference in steric bulk of the two substrates. The different products 3 and 4 are probably a consequence of the difference in size and dispersion force interactions of the AriPr6 and AriPr4 substituents. Compounds 1–4 were characterized by 1H, 13C, and 119Sn NMR, UV–vis, and IR spectroscopy and structurally by X-ray crystallography.
Co-reporter:Shuai Wang, Madison L. McCrea-Hendrick, Cory M. Weinstein, Christine A. Caputo, Elke Hoppe, James C. Fettinger, Marilyn M. Olmstead, and Philip P. Power
Journal of the American Chemical Society May 17, 2017 Volume 139(Issue 19) pp:6596-6596
Publication Date(Web):April 11, 2017
DOI:10.1021/jacs.7b02271
Reactions of the Sn(II) hydrides [ArSn(μ-H)]2 (1) (Ar = AriPr4 (1a), AriPr6 (1b); AriP4 = C6H3-2,6-(C6H3-2,6-iPr2)2, AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2) with norbornene (NB) or norbornadiene (NBD) readily generate the bicyclic alkyl-/alkenyl-substituted stannylenes, ArSn(norbornyl) (2a or 2b) and ArSn(norbornenyl) (3a or 3b), respectively. Heating a toluene solution of 3a or 3b at reflux afforded the rearranged species ArSn(3-tricyclo[2.2.1.02,6]heptane) (4a or 4b), in which the norbornenyl ligand is transformed into a nortricyclyl group. 1H NMR studies of the reactions of 4a or 4b with tert-butylethylene indicated the existence of an apparently unique reversible β-hydride elimination from the bicyclic substituted aryl/alkyl stannylenes 2a or 2b and 3a or 3b. Mechanistic studies indicated that the transformation of 3a or 3b into 4a or 4b occurs via a β-hydride elimination of 1a or 1b to regenerate NBD. Kinetic studies showed that the conversion of 3a or 3b to 4a or 4b is first order. The rate constant k for the conversion of 3a into 3b was determined to be 3.33 × 10–5 min–1, with an activation energy Ea of 16.4 ± 0.7 kcal mol–1.
Co-reporter:Philip P. Power and Ching-Wen Chiu
Inorganic Chemistry August 7, 2017 Volume 56(Issue 15) pp:8597-8597
Publication Date(Web):August 7, 2017
DOI:10.1021/acs.inorgchem.7b01610
Co-reporter:Wenqing Wang, Jing Li, Lei Yin, Yue Zhao, Zhongwen Ouyang, Xinping Wang, Zhenxing Wang, You Song, and Philip P. Power
Journal of the American Chemical Society August 30, 2017 Volume 139(Issue 34) pp:12069-12069
Publication Date(Web):August 8, 2017
DOI:10.1021/jacs.7b06795
Chemical oxidations of piano-stool chromium/cobalt carbonyl complexes Cr(CO)3(η6,η5-C6H5C5H4)Co(CO)2 (1) and Cr(CO)3(η6,η6-C6H5C6H5) Cr(CO)3 (2) were investigated. Upon one-electron oxidation, 1 was transformed to a heterometalloradical species, 1•+. However, either one- or two-electron oxidation of 2 afforded a decomposition product, 3. Dipping 3 into pentane led to the formation of 4 via a crystal-to-crystyal transformation with the removal of solvent molecules. Complexes 1•+ and 4 were fully characterized by various spectroscopic techniques and single-crystal X-ray analysis. Cation 1•+ features a weak Cr–Co bond with a Wiberg bond order of 0.278. A near-infrared absorption band around 1031 nm was observed for 1•+, which is far red-shifted in comparison to previously reported dinuclear metalloradical species. Complex 4 contains a chromium(II) with a distorted pyramidal geometry and displays single-molecule magnetic properties.
Co-reporter:Chun-Yi Lin
Chemical Society Reviews 2017 vol. 46(Issue 17) pp:5347-5399
Publication Date(Web):2017/08/29
DOI:10.1039/C7CS00216E
Nickel plays an important role in areas as diverse as metallurgy, magnetism and biology as well as in chemical applications such as the catalytic transformation of organic substrates. Despite nickel's importance, the investigation of its compounds in various oxidation states remains uneven and those in the +1 oxidation are less common than those in the neighboring 0 and +2 oxidation states. Nonetheless, in recent years, the volume of work on Ni(I) complexes has increased to the extent that they can be no longer regarded as rare. This review focuses on the syntheses and structures of Ni(I) complexes and shows that they display a range of structures, reactivity and magnetic behavior that places them in the forefront of current nickel chemistry research.
Co-reporter:Madison L. McCrea-Hendrick, Christine A. Caputo, Jarno Linnera, Petra Vasko, Cory M. Weinstein, James C. Fettinger, Heikki M. Tuononen, and Philip P. Power
Organometallics 2016 Volume 35(Issue 16) pp:2759-2767
Publication Date(Web):August 9, 2016
DOI:10.1021/acs.organomet.6b00519
The reactions of heavier group 14 element alkyne analogues (EAriPr4)2 (E = Ge, Sn; AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) with the group 6 transition-metal carbonyls M(CO)6 (M = Cr, Mo, W) under UV irradiation resulted in the cleavage of the E–E triple bond and the formation of the complexes {AriPr4EM(CO)4}2 (1–6), which were characterized by single crystal X-ray diffraction as well as by IR and multinuclear NMR spectroscopy. Single-crystal X-ray structural analyses of 1–6 showed that the complexes have a nearly planar rhomboid M2E2 core with three-coordinate group 14 atoms. The coordination geometry at the group 6 metals is distorted octahedral formed by four carbonyl groups as well as two bridging EAriPr4 units. IR spectroscopic data suggest that the EAriPr4 units are not very efficient π-acceptors, but the investigation of E–M metal–metal interactions in 1–6 with computational methods revealed the importance of both σ- and π-type contributions to bonding. The mechanism for the insertion of transition-metal carbonyls into E–E bonds in (EAriPr4)2 was also probed computationally.
Co-reporter:Clifton L. Wagner;Dr. Lizhi Tao;Emily J. Thompson;Dr. Troy A. Stich;Dr. Jingdong Guo;Dr. James C. Fettinger; Louise A. Berben; R. David Britt; Shigeru Nagase; Philip P. Power
Angewandte Chemie 2016 Volume 128( Issue 35) pp:10600-10603
Publication Date(Web):
DOI:10.1002/ange.201605061
Abstract
The synthesis of the first linear coordinated CuII complex Cu{N(SiMe3)Dipp}2 (1 Dipp=C6H5-2,6Pri2) and its CuI counterpart [Cu{N(SiMe3)Dipp}2]− (2) is described. The formation of 1 proceeds through a dispersion force-driven disproportionation, and is the reaction product of a CuI halide and LiN(SiMe3)Dipp in a non-donor solvent. The synthesis of 2 is accomplished by preventing the disproportionation into 1 by using the complexing agent 15-crown-5. EPR spectroscopy of 1 provides the first detailed study of a two-coordinate transition-metal complex indicating strong covalency in the Cu−N bonds.
Co-reporter:Madison L. McCrea-Hendrick, Christine A. Caputo, Christopher J. Roberts, James C. Fettinger, Heikki M. Tuononen, and Philip P. Power
Organometallics 2016 Volume 35(Issue 4) pp:579-586
Publication Date(Web):January 29, 2016
DOI:10.1021/acs.organomet.5b00992
The neutral digallene AriPr4GaGaAriPr4 (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) was shown to react at ca. 25 °C in pentane solution with group 6 transition metal carbonyl complexes M(CO)6 (M = Cr, Mo, W) under UV irradiation to afford compounds of the general formula trans-[M(GaAriPr4)2(CO)4] in modest yields. The bis(gallanediyl) complexes were characterized spectroscopically and by X-ray crystallography, which demonstrated that they were isostructural. In each complex, the gallium atom is two-coordinate with essentially linear geometry, which is relatively rare for gallanediyl-substituted transition metal species. The experimental data show that the gallanediyl ligand :GaAriPr4 behaves as a good σ-donor but a poor π-acceptor, in agreement with prior theoretical analyses on related systems. In addition, the monogallanediyl complex Mo(GaAriPr4)(CO)5 was synthesized by reacting AriPr4GaGaAriPr4 with two equivalents of Mo(CO)5NMe3 in THF solution. The mechanism of the reaction between AriPr4GaGaAriPr4 and Cr(CO)6 was probed computationally using density functional theory. The results suggest that the reaction proceeds via an intermediate monogallanediyl complex, Cr(GaAriPr4)(CO)5, that can be generated via two pathways, one of which involves the dimeric AriPr4GaGaAriPr4, that are possibly competing. AriPr4GaGaAriPr4 was also shown to react readily under ambient conditions with Co2(CO)8 to give the monosubstituted dicobalt complex Co2(μ-GaAriPr4)(μ-CO)(CO)6 by X-ray crystallography. The :GaAriPr4 unit bridges the Co–Co bond unsymmetrically in the solid state. No evidence was found for incorporation of more than one :GaAriPr4 unit into the dicobalt complex.
Co-reporter:Clifton L. Wagner;Dr. Lizhi Tao;Emily J. Thompson;Dr. Troy A. Stich;Dr. Jingdong Guo;Dr. James C. Fettinger; Louise A. Berben; R. David Britt; Shigeru Nagase; Philip P. Power
Angewandte Chemie International Edition 2016 Volume 55( Issue 35) pp:10444-10447
Publication Date(Web):
DOI:10.1002/anie.201605061
Abstract
The synthesis of the first linear coordinated CuII complex Cu{N(SiMe3)Dipp}2 (1 Dipp=C6H5-2,6Pri2) and its CuI counterpart [Cu{N(SiMe3)Dipp}2]− (2) is described. The formation of 1 proceeds through a dispersion force-driven disproportionation, and is the reaction product of a CuI halide and LiN(SiMe3)Dipp in a non-donor solvent. The synthesis of 2 is accomplished by preventing the disproportionation into 1 by using the complexing agent 15-crown-5. EPR spectroscopy of 1 provides the first detailed study of a two-coordinate transition-metal complex indicating strong covalency in the Cu−N bonds.
Co-reporter:Jeremy D. Erickson, Ryan D. Riparetti, James C. Fettinger, and Philip P. Power
Organometallics 2016 Volume 35(Issue 12) pp:2124-2128
Publication Date(Web):June 7, 2016
DOI:10.1021/acs.organomet.6b00344
The tetrylenes Ge(ArMe6)2 and Sn(ArMe6)2 (ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2) reacted with dimethylzinc to afford the insertion products (ArMe6)2Ge(Me)ZnMe (1) and (ArMe6)2Sn(Me)ZnMe (3), which feature Ge–Zn and Sn–Zn bonds as well as two-coordinate zinc atoms. Crystals of 1 were found to be unsuitable for X-ray crystallography, so the ethyl-substituted (ArMe6)2Ge(Et)ZnEt (2) was synthesized in a parallel way to provide crystals suitable for X-ray studies. These showed the structure to be similar to that of 3. The reaction of Pb(ArMe6)2 with dimethylzinc yielded ArMe6ZnMe with a linearly coordinated zinc atom via ligand exchange but no characterizable, new lead product was obtained. The reaction of Sn(ArMe6)2 with dimethylzinc is reversible in hydrocarbon solution at room temperature and displayed a dissociation constant Kdiss and a ΔGdiss of 0.0028(5) and 14(4) kJ mol–1 at 298 K, respectively. Compounds 1–4 were characterized by NMR and IR spectroscopy as well as by X-ray crystallography for 1, 3, and 4.
Co-reporter:Petra Vasko, Akseli Mansikkamäki, James C. Fettinger, Heikki M. Tuononen, Philip P. Power
Polyhedron 2016 Volume 103(Part A) pp:164-171
Publication Date(Web):8 January 2016
DOI:10.1016/j.poly.2015.09.052
Indium(I)chloride reacts with LiArMe6LiArMe6 (ArMe6ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2) in THF to give three new mixed-valent organoindium subhalides. While the 1:1 reaction of InCl with LiArMe6LiArMe6 yields the known metal-rich cluster In8(ArMe6ArMe6)4 (1), the use of freshly prepared LiArMe6LiArMe6 led to incorporation of iodide, derived from the synthesis of LiArMe6LiArMe6, into the structures, to afford In4(ArMe6ArMe6)4I2 (2) along with minor amounts of In3(ArMe6ArMe6)3I2 (3). When the same reaction was performed in 4:3 stoichiometry, the mixed-halide compound In3(ArMe6ArMe6)3ClI (4) was obtained. Further increasing the chloride:aryl ligand ratio resulted in the formation of the known mixed-halide species In4(ArMe6ArMe6)4Cl2I2 that can also be obtained from the reaction of InCl with in situ prepared LiArMe6LiArMe6 in toluene. The new compounds 2 and 4 were characterized in the solid state by X-ray crystallography and IR spectroscopy, and in solution by UV/Vis and 1H/13C{1H} NMR spectroscopies. The structural characterization of 2 and 4 was supported by electronic structure calculations at the density functional level of theory which were also performed to rationalize the cluster-type bonding in 1.The synthesis and characterization of two new mixed-valent indium subhalides is presented. Reactions of LiArMe6LiArMe6 with varying amounts of In(I)Cl yield products incorporating different halides depending on the reaction conditions. DFT calculations were performed to investigate the electronic structures of the compounds as well as that of the cluster In8(ArMe6ArMe6)4.
Co-reporter:Jing-Dong Guo, David J. Liptrot, Shigeru Nagase and Philip P. Power
Chemical Science 2015 vol. 6(Issue 11) pp:6235-6244
Publication Date(Web):19 Aug 2015
DOI:10.1039/C5SC02707A
The structures and bonding in the heavier group 14 element olefin analogues [E{CH(SiMe3)2}2]2 and [E{N(SiMe3)2}2]2 (E = Ge, Sn, or Pb) and their dissociation into :E{CH(SiMe3)2}2 and :E{N(SiMe3)2}2 monomers were studied computationally using hybrid density functional theory (DFT) at the B3PW91 with basis set superposition error and zero point energy corrections. The structures were reoptimized with the dispersion-corrected B3PW91-D3 method to yield dispersion force effects. The calculations generally reproduced the experimental structural data for the tetraalkyls with a few angular exceptions. For the alkyls, without the dispersion corrections, dissociation energies of −2.3 (Ge), +2.1 (Sn), and −0.6 (Pb) kcal mol−1 were calculated, indicating that the dimeric E–E bonded structure is favored only for tin. However, when dispersion force effects are included, much higher dissociation energies of 28.7 (Ge), 26.3 (Sn), and 15.2 (Pb) kcal mol−1 were calculated, indicating that all three E–E bonded dimers are favored. Calculated thermodynamic data at 25 °C and 1 atm for the dissociation of the alkyls yield ΔG values of 9.4 (Ge), 7.1 (Sn), and −1.7 (Pb) kcal mol−1, indicating that the dimers of Ge and Sn, but not Pb, are favored. These results are in harmony with experimental data. The dissociation energies for the putative isoelectronic tetraamido-substituted dimers [E{N(SiMe3)2}2]2 without dispersion correction are −7.0 (Ge), −7.4 (Sn), and −4.8 (Pb) kcal mol−1, showing that the monomers are favored in all cases. Inclusion of the dispersion correction yields the values 3.6 (Ge), 11.7 (Sn), and 11.8 (Pb) kcal mol−1, showing that dimerization is favored but less strongly so than in the alkyls. The calculated thermodynamic data for the amido germanium, tin, and lead dissociation yield ΔG values of −12.2, −3.7, and −3.6 kcal mol−1 at 25 °C and 1 atm, consistent with the observation of monomeric structures. Overall, these data indicate that, in these sterically-encumbered molecules, dispersion force attraction between the ligands is of greater importance than group 14 element–element bonding, and is mainly responsible for the dimerization of the metallanediyls species to give the dimetallenes. In addition, calculations on the non-dissociating distannene [Sn{SiMetBu2}2]2 show that the attractive dispersion forces are key to its stability.
Co-reporter:C.-Y. Lin, J. C. Fettinger, N. F. Chilton, A. Formanuik, F. Grandjean, G. J. Long and P. P. Power
Chemical Communications 2015 vol. 51(Issue 68) pp:13275-13278
Publication Date(Web):07 Jul 2015
DOI:10.1039/C5CC05166E
The reduction of Mn{C(SiMe3)3}2 with KC8 in the presence of crown ethers yielded the d6, Mn(I) salts [K2(18-crown-6)3][Mn{C(SiMe3)3}2]2 and [K(15-crown-5)2][Mn{C(SiMe3)3}2], that have near-linear manganese coordination but almost completely quenched orbital magnetism as a result of 4s–3dz2 orbital mixing which affords a non-degenerate ground state.
Co-reporter:Pei Zhao; Hao Lei; Chengbao Ni; Jing-Dong Guo; Saeed Kamali; James C. Fettinger; Fernande Grandjean; Gary J. Long; Shigeru Nagase
Inorganic Chemistry 2015 Volume 54(Issue 18) pp:8914-8922
Publication Date(Web):September 2, 2015
DOI:10.1021/acs.inorgchem.5b00930
The bis(μ-oxo) dimeric complexes {AriPr8OM(μ-O)}2 (AriPr8 = C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2; M = Fe (1), Co (2)) were prepared by oxidation of the M(I) half-sandwich complexes {AriPr8M(η6-arene)} (arene = benzene or toluene). Iron species 1 was prepared by reacting {AriPr8Fe(η6-benzene)} with N2O or O2, and cobalt species 2 was prepared by reacting {AriPr8Co(η6-toluene)} with O2. Both 1 and 2 were characterized by X-ray crystallography, UV–vis spectroscopy, magnetic measurements, and, in the case of 1, Mössbauer spectroscopy. The solid-state structures of both compounds reveal unique M2(μ-O)2 (M = Fe (1), Co(2)) cores with formally three-coordinate metal ions. The Fe···Fe separation in 1 bears a resemblance to that in the Fe2(μ-O)2 diamond core proposed for the methane monooxygenase intermediate Q. The structural differences between 1 and 2 are reflected in rather differing magnetic behavior. Compound 2 is thermally unstable, and its decomposition at room temperature resulted in the oxidation of the AriPr8 ligand via oxygen insertion and addition to the central aryl ring of the terphenyl ligand to produce the 5,5′-peroxy-bis[4,6-iPr2-3,7-bis(2,4,6-iPr3-phenyl)oxepin-2(5H)-one] (3). The structure of the oxidized terphenyl species is closely related to that of a key intermediate proposed for the oxidation of benzene.
Co-reporter:Jeremy D. Erickson, James C. Fettinger, and Philip P. Power
Inorganic Chemistry 2015 Volume 54(Issue 4) pp:1940-1948
Publication Date(Web):January 28, 2015
DOI:10.1021/ic502824w
The reaction of the tetrylenes Ge(ArMe6)2, Sn(ArMe6)2, and Pb(ArMe6)2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2] with the group 13 metal alkyls trimethylaluminum and trimethylgallium afforded (ArMe6)2Ge(Me)AlMe2 (1), (ArMe6)2Ge(Me)GaMe2 (2), and (ArMe6)2Sn(Me)GaMe2 (3) in good yields via insertion reaction routes. In contrast, the reaction of AlMe3 with Sn(ArMe6)2 afforded the [1.1.1]propellane analogue Sn2{Sn(Me)ArMe6}3 (5) in low yield, and the reaction of AlMe3 or GaMe3 with Pb(ArMe6)2 resulted in the formation of the diplumbene {Pb(Me)ArMe6}2 (6) and AlArMe6Me2 (7) or GaArMe6Me2 (8) via metathesis. The reaction of Sn(ArMe6)2 with gallium trialkyls was found to be reversible under ambient conditions and analyzed through the reaction of Sn(ArMe6)2 with GaEt3 to form (ArMe6)2Sn(Et)GaEt2 (4), which displayed a dissociation constant Kdiss and ΔGdiss of 8.09(6) × 10–3 and 11.8(9) kJ mol–1 at 296 °C. The new compounds were characterized by X-ray crystallography, NMR (1H, 13C, 119Sn, and 207Pb), IR, and UV–vis spectroscopies.
Co-reporter:Nicholas F. Chilton, Hao Lei, Aimee M. Bryan, Fernande Grandjean, Gary J. Long and Philip P. Power
Dalton Transactions 2015 vol. 44(Issue 24) pp:11202-11211
Publication Date(Web):18 May 2015
DOI:10.1039/C5DT01589H
The 2 to 300 K magnetic susceptibilities of Fe{N(SiMe2Ph)2}2, 1, Fe{N(SiMePh2)2}2, 2, and the diaryl complex Fe(ArPri4)2, 3, where ArPri4 is C6H3-2,6(C6H3-2,6-Pri2)2 have been measured. Initial fits of these properties in the absence of an independent knowledge of their ligand field splitting have proven problematic. Ab initio calculations of the CASSCF/RASSI/SINGLE-ANISO type have indicated that the orbital energies of the complexes, as well as those of Fe(ArMe6)2, 4, where ArMe6 is C6H3-2,6(C6H2-2,4,6-Me3)2), are in the order dxy ≈ dx2−y2 < dxz ≈ dyz < dz2, and the iron(II) complexes in this ligand field have the (dxy, dx2−y2)3(dxz, dyz)2(dz2)1 ground electronic configuration with a substantial orbital contribution to their effective magnetic moments. An ab initio-derived ligand field and spin–orbit model is found to yield an excellent simulation of the observed magnetic properties of 1–3. The calculated ligand field strengths of these ligands are placed in the broader context of common coordination ligands in hypothetical two-coordinate linear iron(II) complexes. This yields the ordering I− < H− < Br− ≈ PMe3 < CH3− < Cl− ≈ C(SiMe3)3− < CN− ≈ SArPri6− < ArPri4− < ArMe6− ≈ N3− < NCS− ≈ NCSe− ≈ NCBH3− ≈ MeCN ≈ H2O ≈ NH3 < NO3− ≈ THF ≈ CO ≈ N(SiMe2Ph)2− ≈ N(SiMePh2)2− < F− ≈ N(H)ArPri6− ≈ N(SiMe3)Dipp− < OArPri4−. The magnetic susceptibility of the bridged dimer, [Fe{N(SiMe3)2}2]2, 5, has also been measured between 2 and 300 K and a fit of χMT with the isotropic Heisenberg Hamiltonian, Ĥ = −2JŜ1·Ŝ2 yields an antiferromagnetic exchange coupling constant, J, of −131(2) cm−1.
Co-reporter:Jeremy D. Erickson, Petra Vasko, Ryan D. Riparetti, James C. Fettinger, Heikki M. Tuononen, and Philip P. Power
Organometallics 2015 Volume 34(Issue 24) pp:5785-5791
Publication Date(Web):December 8, 2015
DOI:10.1021/acs.organomet.5b00884
Reactions of the divalent germylene Ge(ArMe6)2 (ArMe6 = C6H3-2,6-{C6H2-2,4,6-(CH3)3}2) with water or methanol gave the Ge(IV) insertion product (ArMe6)2Ge(H)OH (1) or (ArMe6)2Ge(H)OMe (2), respectively. In contrast, its stannylene congener Sn(ArMe6)2 reacted with water or methanol to produce the Sn(II) species {ArMe6Sn(μ-OH)}2 (3) or {ArMe6Sn(μ-OMe)}2 (4), respectively, with elimination of ArMe6H. Compounds 1–4 were characterized by IR and NMR spectroscopy as well as by X-ray crystallography. Density functional theory calculations yielded mechanistic insight into the formation of (ArMe6)2Ge(H)OH and {ArMe6Sn(μ-OH)}2. The insertion of an m-terphenyl-stabilized germylene into the O–H bond was found to be catalytic, aided by a second molecule of water. The lowest energy pathway for the elimination of arene from the corresponding stannylene involved sigma-bond metathesis rather than separate oxidative addition and reductive elimination steps. The reactivity of Sn(ArMe6)2 with water or methanol contrasts with that of Sn{(CH(SiMe3)2}2, which affords the Sn(IV) insertion products {(Me3Si)2CH}2Sn(H)OH and {(Me3Si)2CH}2Sn(H)OMe. The differences were tentatively ascribed to the Lewis basicity of the employed solvent (Et2O vs THF) and the use of molar vs millimolar concentrations of the substrate.
Co-reporter:Petra Wilfling, Kathrin Schittelkopf, Michaela Flock, Rolfe H. Herber, Philip P. Power, and Roland C. Fischer
Organometallics 2015 Volume 34(Issue 11) pp:2222-2232
Publication Date(Web):December 12, 2014
DOI:10.1021/om500946e
The synthesis and characterization of a series of heavier group 14 element (Ge, Sn, and Pb) carbene homologues based on the electronically modified, 2,6-dimesityl substituted terphenyl ligands Ar#-3,5-iPr2, Ar#-4-SiMe3, and Ar#-4-Cl (Ar#-3,5-iPr2 = C6H2-2,6-Mes2-3,5-iPr2; Ar#-4-Cl = C6H2-2,6-Mes2-4-Cl; Ar#-4-SiMe3 = C6H2-2,6-Mes2-4-SiMe3; Mes = C6H2-2,4,6-Me3) are presented. The consequences of introducing electron withdrawing and -releasing substituents on the solid state structures of the newly synthesized germylenes, stannylenes, and plumbylenes as well as their Mössbauer, NMR and UV–vis spectroscopic properties are presented and discussed in the context of a second order Jahn–Teller type mixing of frontier orbitals with appropriate symmetry. Experimental findings were supported by DFT calculations. More electron withdrawing ligands lead to a bonding situation with higher contribution of p-orbitals from the central heavier group 14 element in σ-bonding toward the ligands and thus increased s-electron character of the lone pair. Furthermore, this results in an increase in the energy separation between the frontier orbitals. Experimentally, these changes are manifested in narrower bending angles at the heavy tetrel atoms and hypsochromic in their UV–vis spectra. In contrast, derivatives of more electron rich m-terphenyl ligands are characterized by a smaller HOMO–LUMO gap and wider interligand angles.
Co-reporter:Jing-Dong Guo, Shigeru Nagase, and Philip P. Power
Organometallics 2015 Volume 34(Issue 10) pp:2028-2033
Publication Date(Web):May 13, 2015
DOI:10.1021/acs.organomet.5b00254
The dissociation of the sterically encumbered diphosphanes and diarsanes [:E{CH(SiMe3)2}2]2 (E = P or As) and [:E{N(SiMe3)2}2]2 (E = P or As) into :Ė{CH(SiMe3)2}2 or :Ė{N(SiMe3)2}2 radical monomers was studied computationally using hybrid density functional theory (DFT) at the B3PW91 with the 6–311+G(d) basis set for P and As, and the 6–31G(d,p) basis set for other atoms. The structures were reoptimized with the dispersion corrected B3PW91–D3 method to estimate dispersion force effects. The calculations reproduced the experimental structural data for the tetraalkyls with good accuracy. Without the dispersion correction, negative dissociation energies of −10.3 and −6.5 kcal mol–1 were calculated for the phosphorus and arsenic tetraalkyls, indicating that the radical monomers are more stable. In contrast, the incorporation of dispersion force effects afforded high, positive dissociation energies of +37.6 and +37.1 kcal mol–1 that favored dimeric structures. The dissociation energies (without dispersion) calculated for the tetraamido-substituted dimer are also negative, but changed to positive values of +29.3 and +32.5 kcal mol–1 upon optimization with the D3 dispersion term. In contrast to earlier calculations, which indicated that the release of accumulated strain energy within the tetraalkyl dimers was the driving force for dissociation to monomers (i.e., the “Jack-in-the-Box” molecular model), the current calculations show that dispersion force attractive interactions exceed those of ligand relaxation and stabilize the dimeric structures. Single-point MP2 (second-order Møller–Plesset perturbation theory) calculations including dispersion effects afforded dissociation energies of 30.4 and 30.8 kcal mol–1 for the tetraalkyl species, suggesting that the addition of the D3 dispersion term to the B3PW91 functional may overestimate such forces by 7–8 kcal mol–1. It is concluded that the balance of dispersion forces and entropic effects are the major determinants of the dissociation equilibria.
Co-reporter:Mario Carrasco ; Irene Mendoza ; Michelle Faust ; Joaquín López-Serrano ; Riccardo Peloso ; Amor Rodríguez ; Eleuterio Álvarez ; Celia Maya ; Philip. P. Power ;Ernesto Carmona
Journal of the American Chemical Society 2014 Volume 136(Issue 25) pp:9173-9180
Publication Date(Web):May 29, 2014
DOI:10.1021/ja503750a
Mono- and bis-terphenyl complexes of molybdenum and tungsten with general composition M2(Ar′)(O2CR)3 and M2(Ar′)2(O2CR)2, respectively (Ar′ = terphenyl ligand), that contain carboxylate groups bridging the quadruply bonded metal atoms, have been prepared and structurally characterized. The new compounds stem from the reactions of the dimetal tetracarboxylates, M2(O2CR)4 (M = Mo, R = H, Me, CF3; M = W, R = CF3) with the lithium salts of the appropriate terphenyl groups (Ar′ = ArXyl2, ArMes2, ArDipp2, and ArTrip2). Substitution of one bidentate carboxylate by a monodentate terphenyl forms a M–C σ bond and creates a coordination unsaturation at the other metal atom. Hence in M2(Ar′)2(O2CR)2 complexes the two metal atoms have formally a low coordination number and an also low electron count. However, the unsaturation seems to be compensated by a weak M–Carene bonding interaction that implicates one of the aryl substituents of the terphenyl central aryl ring, as revealed by X-ray studies performed with some of these complexes and by theoretical calculations.
Co-reporter:Felicitas Lips, Joshua D. Queen, James C. Fettinger and Philip P. Power
Chemical Communications 2014 vol. 50(Issue 42) pp:5561-5564
Publication Date(Web):02 Apr 2014
DOI:10.1039/C4CC00999A
Reactions of the tetrylenes Ge(SArMe6)2 (1) (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2), and Sn(SArMe6)2 (2) with (Mo(CO)4(NBD) (NBD = bicyclo[2.2.1]hepta-2,5-diene) gave three new, unusual complexes [Mo(THF)(CO)3{Ge(SArMe6)2}] (3), [Mo(THF)(CO)3{Ge(SArMe6)2}] (4) and [Mo(CO)4{Sn(SArMe6)2}] (5) which display no significant Ge/Sn–Mo bonding. Instead the ligands are coordinated to molybdenum in a bidentate fashion via the thiolato sulfurs.
Co-reporter:Aimee M. Bryan, Chun-Yi Lin, Michio Sorai, Yuji Miyazaki, Helen M. Hoyt, Annelise Hablutzel, Anne LaPointe, William M. Reiff, Philip P. Power, and Charles E. Schulz
Inorganic Chemistry 2014 Volume 53(Issue 22) pp:12100-12107
Publication Date(Web):November 4, 2014
DOI:10.1021/ic501925e
Co-reporter:Chun-Yi Lin, James C. Fettinger, Fernande Grandjean, Gary J. Long, and Philip P. Power
Inorganic Chemistry 2014 Volume 53(Issue 17) pp:9400-9406
Publication Date(Web):August 13, 2014
DOI:10.1021/ic501534f
Three potassium crown ether salts, [K(Et2O)2(18-crown-6)][Fe{N(SiMe3)Dipp}2] (1a; Dipp = C6H3-2,6-Pri2), [K(18-crown-6)][Fe{N(SiMe3)Dipp}2]·0.5PhMe (1b), and [K(18-crown-6)][M{N(SiMe3)Dipp}2] (M = Co, 2; M = Ni, 3), of the two-coordinate linear or near-linear bis-amido monoanions [M{N(SiMe3)Dipp}2]− (M = Fe, Co, Ni) were synthesized by one-electron reduction of the neutral precursors M{N(SiMe3)Dipp}2 with KC8 in the presence of 18-crown-6. They were characterized by X-ray crystallography, UV–vis spectroscopy, cyclic voltammetry, and magnetic measurements. The anions feature lengthened M–N bonds in comparison with their neutral precursors, with slightly bent coordination (N–Fe–N = ca. 172°) for the iron(I) complex, but linear coordination for the cobalt(I) and nickel(I) complexes. Fits of the temperature dependence of χMT of 1 and 2 reveal that the iron(I) and cobalt(I) complexes have large negative D zero-field splittings and a substantial orbital contribution to their magnetic moments with L = 2, whereas the nickel(I) complex has at most a small orbital contribution to its magnetic moment. The magnetic results have been used to propose an ordering of the 3d orbitals in each of the complexes.
Co-reporter:Aimee M. Bryan, Gary J. Long, Fernande Grandjean, and Philip P. Power
Inorganic Chemistry 2014 Volume 53(Issue 5) pp:2692-2698
Publication Date(Web):February 17, 2014
DOI:10.1021/ic403098p
Treatment of the cobalt(II) amide, [Co{N(SiMe3)2}2]2, with four equivalents of the sterically crowded terphenyl phenols, HOArMe6 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2) or HOAriPr4 (AriPr4 = C6H3-2,6(C6H3-2,6-Pri2)2), produced the first well-characterized, monomeric two-coordinate cobalt(II) bisaryloxides, Co(OArMe6)2 (1) and Co(OAriPr4)2 (2a and 2b), as red solids in good yields with elimination of HN(SiMe3)2. The compounds were characterized by electronic spectroscopy, X-ray crystallography, and direct current magnetization measurements. The O–Co–O interligand angles in 2a and 2b are 180°, whereas the O–Co–O angle in 1 is bent at 130.12(8)° and its cobalt(II) ion has a highly distorted pseudotetrahedral geometry with close interactions to the ipso-carbons of the two flanking aryl rings. The Co–O distances in 1, 2a, and 2b are 1.858(2), 1.841(1), and 1.836(2) Å respectively. Structural refinement revealed that 1, 2a, and 2b have different fractional occupations of the cobalt site in their crystal structures: 1, 95.0%, 2a, 93.5%, and 2b, 84.6%. Correction of the magnetic data for the different cobalt(II) occupancies showed that the magnetization of 2a and 2b was virtually identical. The effective magnetic moments for 1, 2a, and 2b, 5.646(5), 5.754(5), and 5.636(3) μB respectively, were indicative of significant spin–orbit coupling. The differences in magnetic properties between 1 and 2a/2b are attributed to their different cobalt coordination geometries.
Co-reporter:Felicitas Lips, James C. Fettinger, Philip P. Power
Polyhedron 2014 Volume 79() pp:207-212
Publication Date(Web):5 September 2014
DOI:10.1016/j.poly.2014.04.056
The reaction of the bulky lithium terphenyl thiolates LiSArMe6 (ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2) and LiSAriPr4 (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) with AlBr3 in PhMe or Et2O resulted in the formation of two new lithium aluminum thiolate salts LiAl(SArMe6)2Br2·PhMe 1, [LiAl(SArMe6)Br3]22, and the etherate Al(SAriPr4)Br2(OEt2) 3. Compounds 1–3 were structurally characterized and analyzed by 1H, 13C NMR and IR spectroscopy. In further investigations the reduction of 1 and 2 with KC8 or Rieke’s magnesium in different solvent systems afforded the compounds KAl(SArMe6)3H·2PhMe 4 and LiAl(SArMe6)Br0.36I1.64(2THF)·PhMe 5. All of the compounds described herein contain four-coordinate aluminum atoms with distorted tetrahedral geometries.Graphical abstractThe terphenyl thiolato aluminates LiAl(SArMe6)2Br2·PhMe, LiAl(SArMe6)Br3 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)) and the neutral Al(SArPri4)Br2(OEt2) (ArPri4 = C6H3-2,6(C6H3-2,6-iPr2)2) were obtained by the reactions of the lithium thiolates with AlBr3. Their reduction with KC8 or Rieke’s magnesium afforded aluminum thiolates/hydrides or the incorporation of iodine in place of bromine but no Al–Al bond formation.
Co-reporter:Pei Zhao, Zachary Brown, James C. Fettinger, Fernande Grandjean, Gary J. Long, and Philip P. Power
Organometallics 2014 Volume 33(Issue 8) pp:1917-1920
Publication Date(Web):April 15, 2014
DOI:10.1021/om500180u
The homoleptic cobalt(I) alkyl [Co{C(SiMe2Ph)3}]2 (1) was prepared by reacting CoCl2 with [Li{C(SiMe2Ph)3}(THF)] in a 1:2 ratio. Attempts to synthesize the corresponding iron(I) species led to the iron(II) salt [Li(THF)4][Fe2(μ-Cl)3{C(SiMe2Ph)3}2] (2). Both 1 and 2 were characterized by X-ray crystallography, UV–vis spectroscopy, and magnetic measurements. The structure of 1 consists of dimeric units in which each cobalt(I) ion is σ-bonded to the central carbon of the alkyl group −C(SiMe2Ph)3 and π-bonded to one of the phenyl rings of the −C(SiMe2Ph)3 ligand attached to the other cobalt(I) ion in the dimer. The structure of 2 features three chlorides bridging two iron(II) ions. Each iron(II) ion is also σ-bonded to the central carbon of a terminal −C(SiMe2Ph)3 anionic ligand. The magnetic properties of 1 reveal the presence of two independent cobalt(I) ions with S = 1 and a significant zero-field splitting of D = 38.0(2) cm–1. The magnetic properties of 2 reveal extensive antiferromagnetic exchange coupling with J = −149(4) cm–1 and a large second-order Zeeman contribution to its molar magnetic susceptibility. Formation of the alkyl 1 and the halide complex 2 under similar conditions is probably due in part to the fact that Co(II) is more readily reduced than Fe(II).
Co-reporter:Christopher E. Melton, Jonathan W. Dube, Paul J. Ragogna, James C. Fettinger, and Philip P. Power
Organometallics 2014 Volume 33(Issue 1) pp:329-337
Publication Date(Web):December 19, 2013
DOI:10.1021/om4010675
The synthesis and characterization of the sterically crowded primary alanes (AriPr4AlH2)2 (AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) and (AriPr8AlH2)2 (AriPr8 = C6H-2,6(C6H2-2,4,6-iPr6)2-3,5-iPr2) are described. They, along with their previously reported less-hindered analogue (ArMe6AlH2)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2), were reacted with ammonia to give the parent amido alanes {ArxAl(H)NH2}2 (Arx = ArMe6, 1; AriPr4, 2; AriPr8, 3), which are the first well-characterized hydride amido derivatives of aluminum and are relatively rare examples of parent aluminum amides. In contrast, the reaction of (ArMe6AlH2)2 with phosphine yielded the structurally unique Al/P cage species {(ArMe6Al)3(μ-PH2)3(μ-PH)PH2} (4) as the major product and a smaller amount of {(ArMe6Al)4(μ-PH2)4(μ-PH)} (5) as a minor product. All compounds were characterized by NMR and IR spectroscopy, while compounds 2–5 were also characterized by X-ray crystallography.
Co-reporter: Philip Power
Angewandte Chemie International Edition 2014 Volume 53( Issue 27) pp:
Publication Date(Web):
DOI:10.1002/anie.201404980
Co-reporter:James C. Fettinger, Paul A. Gray, Christopher E. Melton, and Philip P. Power
Organometallics 2014 Volume 33(Issue 21) pp:6232-6240
Publication Date(Web):October 15, 2014
DOI:10.1021/om500911f
The reactions of the sterically crowded primary alane (ArPri8AlH2)2 (ArPri8 = C6H-2,6(C6H2-2,4,6-Pri3)2-3,5-Pri2) with alkynes and alkenes are described. It is shown that hydroalumination of the terminal alkynes HCCSiMe3 and HCCPh readily occurs under mild conditions via the cis-addition of the Al–H moiety across the CC triple bond with no evidence of hydrogen elimination. Hydroalumination was observed also with a range of terminal olefins, but no reactivity was observed with internal alkenes or alkynes. The relatively high reactivity of (ArPri8AlH2)2 was attributed to the steric crowding of the large terphenyl substituent, which favors dissociation of the alane and increases the availability of the more reactive three-coordinate aluminum site in the monomer. In keeping with this view, studies of the reactions of the three primary alanes (ArPri8AlH2)2, (ArPri4AlH2)2 (ArPri4 = C6H3-2,6(C6H3-2,6-Pri2)2), and (ArMe6AlH2)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2) with alkenes showed that the reaction rates are inversely proportional to the size of the terphenyl substituent, consistent with higher reactivity of the aluminum monomer. The structures of the alkenyl insertion products, ArPri8Al(CHCHPh)2 and ArPri8Al(CHCHSiMe3)2, the alkylated derivative, ArPri8Al(CH2CH2SiMe3)2, and the precursor aluminates {Li(OEt2)H3AlArPri8·Li(OEt2)2H3AlArPri8}, (LiH3AlArPri8)2, and alanes (ArPri8AlH2)2, and (ArPri4AlH2)2 were determined by X-ray crystallography.
Co-reporter:Felicitas Lips, Akseli Mansikkamäki, James C. Fettinger, Heikki M. Tuononen, and Philip P. Power
Organometallics 2014 Volume 33(Issue 21) pp:6253-6258
Publication Date(Web):October 9, 2014
DOI:10.1021/om500947x
Cycloaddition reactions of the acyclic silylene Si(SAriPr4)2 (AriPr4 = C6H3-2,6(C6H3-2,6-iPr2)2) with a variety of alkenes and alkynes were investigated. Its reactions with the alkynes phenylacetylene and diphenylacetylene and the diene 2,3-dimethyl-1,3-butadiene yielded silacycles (AriPr4S)2Si(CH═CPh) (1), (AriPr4S)2Si(PhC═CPh) (2), and (AriPr4S)2SiCH2CMeCMeCH2 (3) at ambient temperature. The compounds were characterized by X-ray crystallography, 1H, 13C, and 29Si NMR spectroscopy, and IR spectroscopy. No reaction was observed with more substituted alkenes such as propene, (Z)-2-butene, tert-butylethylene, cyclopentene, 1-hexene, or the alkyne bis(trimethylsilyl)acetylene under the same reaction conditions. The germylene Ge(SArMe6)2 and stannylene Sn(SArMe6)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2) analogues of Si(SArMe6)2 displayed no reaction with ethylene. Quantum chemical calculations using model tetrylenes E(SPh)2 (E = Si, Ge, Sn; Ph = C6H5) show that cyclization reactions are endothermic in the case of germanium and tin derivatives but energetically favored for the silicon species.
Co-reporter: Philip Power
Angewandte Chemie 2014 Volume 126( Issue 27) pp:
Publication Date(Web):
DOI:10.1002/ange.201404980
Co-reporter:Felicitas Lips ; James C. Fettinger ; Akseli Mansikkamäki ; Heikki M. Tuononen
Journal of the American Chemical Society 2013 Volume 136(Issue 2) pp:634-637
Publication Date(Web):December 23, 2013
DOI:10.1021/ja411951y
Treatment of toluene solutions of the silylenes Si(SArMe6)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2, 1) or Si(SArPri4)2 (ArPri4 = C6H3-2,6(C6H3-2,6-Pri2)2, 2) with excess ethylene gas affords the siliranes (ArMe6S)2SiCH2CH2 (3) or (ArPri4S)2SiCH2CH2 (4). Silirane 4 evolves ethylene spontaneously at room temperature in toluene solution. A Van’t Hoff analysis by variable-temperature 1H NMR spectroscopy showed that ΔGassn = −24.9(2.5) kJ mol–1 for 4. A computational study of the reaction mechanism using a model silylene Si(SPh)2 (Ph = C6H5) was in harmony with the Van’t Hoff analysis, yielding ΔGassn = −24 kJ mol–1 and an activation energy ΔG⧧ = 54 kJ mol–1.
Co-reporter:Jessica N. Boynton ; Jing-Dong Guo ; James C. Fettinger ; Christopher E. Melton ; Shigeru Nagase
Journal of the American Chemical Society 2013 Volume 135(Issue 29) pp:10720-10728
Publication Date(Web):June 19, 2013
DOI:10.1021/ja403244w
The synthesis and characterization of the first stable two-coordinate vanadium complexes are described. The vanadium(II) primary amido derivative V{N(H)AriPr6}2 [AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2] (1) was synthesized via the reaction of LiN(H)AriPr6 with the V(III) complex VCl3·2NMe3 or the V(II) salt [V2Cl3(THF)6]+I– in a 2:1 and 4:1 stoichiometry, respectively. Reaction of the less crowded LiN(H)ArMe6 with [V2Cl3(THF)6]+I– afforded V{N(H)ArMe6}2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2] (2), which has a nonlinear [N–V–N = 123.47(9)°] vanadium coordination. Magnetometry studies showed that V{N(H)AriPr6}2 and V{N(H)ArMe6}2 have ambient temperature magnetic moments of 3.41 and 2.77 μB, respectively, which are consistent with a high-spin d3 electron configuration. These values suggest a significant spin orbital angular momentum contribution that leads to a magnetic moment that is lower than their spin-only value of 3.87 μB. DFT calculations showed that the major absorptions in their UV–vis spectra were due to ligand to metal charge transfer transitions. Exposure of the reaction mixture for 2 to dry O2 resulted in the formation of the diamagnetic V(V) oxocluster [V{N(H)ArMe6}2]2(μ-O–Li–O)2 (3).
Co-reporter:Brian D. Rekken ; Thomas M. Brown ; James C. Fettinger ; Felicitas Lips ; Heikki M. Tuononen ; Rolfe H. Herber
Journal of the American Chemical Society 2013 Volume 135(Issue 27) pp:10134-10148
Publication Date(Web):May 30, 2013
DOI:10.1021/ja403802a
The synthesis and spectroscopic and structural characterization of an extensive series of acyclic, monomeric tetrylene dichalcogenolates of formula M(ChAr)2 (M = Si, Ge, Sn, Pb; Ch = O, S, or Se; Ar = bulky m-terphenyl ligand, including two new acyclic silylenes) are described. They were found to possess several unusual features—the most notable of which is their strong tendency to display acute interligand, Ch–M–Ch, bond angles that are often well below 90°. Furthermore, and contrary to normal steric expectations, the interligand angles were found to become narrower as the size of the ligand was increased. Experimental and structural data in conjunction with high-level DFT calculations, including corrections for dispersion effects, led to the conclusion that dispersion forces play an important role in stabilizing their acute interligand angles.
Co-reporter:Zachary D. Brown ; Petra Vasko ; Jeremy D. Erickson ; James C. Fettinger ; Heikki M. Tuononen
Journal of the American Chemical Society 2013 Volume 135(Issue 16) pp:6257-6261
Publication Date(Web):March 11, 2013
DOI:10.1021/ja4003553
An experimental and DFT investigation of the mechanism of the coupling of methylisocyanide and C–H activation mediated by the germylene (germanediyl) Ge(ArMe6)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2) showed that it proceeded by initial MeNC adduct formation followed by an isomerization involving the migratory insertion of the MeNC carbon into the Ge–C ligand bond. Addition of excess MeNC led to sequential insertions of two further MeNC molecules into the Ge–C bond. The insertion of the third MeNC leads to methylisocyanide methyl group C–H activation to afford an azagermacyclopentadienyl species. The X-ray crystal structures of the 1:1 (ArMe6)2GeCNMe adduct, the first and final insertion products (ArMe6)GeC(NMe)ArMe6 and (ArMe6)GeC(NHMe)C(NMe)C(ArMe6)NMe were obtained. The DFT calculations on the reaction pathways represent the first detailed mechanistic study of isocyanide oligomerization by a p-block element species.
Co-reporter:Christine A. Caputo ; Juha Koivistoinen ; Jani Moilanen ; Jessica N. Boynton ; Heikki M. Tuononen
Journal of the American Chemical Society 2013 Volume 135(Issue 5) pp:1952-1960
Publication Date(Web):January 23, 2013
DOI:10.1021/ja3116789
The mechanism of the reaction of olefins and hydrogen with dimetallenes ArMMAr (Ar = aromatic group; M = Al or Ga) was studied by density functional theory calculations and experimental methods. The digallenes, for which the most experimental data are available, are extensively dissociated to gallanediyl monomers, :GaAr, in hydrocarbon solution, but the calculations and experimental data showed also that they react with simple olefins, such as ethylene, as intact ArGaGaAr dimers via stepwise [2 + 2 + 2] cycloadditions due to their considerably lower activation barriers vis-à-vis the gallanediyl monomers, :GaAr. This pathway was preferred over the [2 + 2] cycloaddition of olefin to monomeric :GaAr to form a gallacyclopropane ring with subsequent dimerization to yield the 1,2-digallacyclobutane intermediate and, subsequently, the 1,4-digallacyclohexane product. The calculations showed also that the addition of H2 to digallene proceeds by a different mechanism involving the initial addition of one equivalent of H2 to form a 1,2-dihydride intermediate. This reacts with a second equivalent of H2 to give two ArGaH2 fragments which recombine to give the observed product with terminal and bridging H-atoms, Ar(H)Ga(μ-H)2Ga(H)Ar. The computations agree with the experimental observation that the :GaAriPr8 (AriPr8 = C6H-2,6-(C6H3-2,4,6-iPr3)2-3,5-iPr2), which does not associate even in the solid state, does not react with ethylene or hydrogen. Calculations on the reaction of propene with ArAlAlAr show that, in contrast to the digallenes, addition involves an open-shell transition state consistent with the higher singlet diradical character of dialuminenes.
Co-reporter:Jessica N. Boynton ; Jing-Dong Guo ; Fernande Grandjean ; James C. Fettinger ; Shigeru Nagase ; Gary J. Long
Inorganic Chemistry 2013 Volume 52(Issue 24) pp:14216-14223
Publication Date(Web):November 22, 2013
DOI:10.1021/ic4021355
The titanium bisamido complex Ti{N(H)AriPr6}2 (AriPr6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2 (2), along with its three-coordinate titanium(III) precursor, TiCl{N(H)AriPr6}2 (1), have been synthesized and characterized. Compound 1 was obtained via the stoichiometric reaction of LiN(H)AriPr6 with the Ti(III) complex TiCl3·2NMe3 in trimethylamine. Reduction of 1 with 1 equiv of KC8 afforded Ti{N(H)AriPr6}2 (2) in moderate yield. Both 1 and 2 were characterized by X-ray crystallography, NMR, and IR spectroscopy, magnetic studies, and by density functional theory (DFT) computations. The precursor 1 has quasi-four-coordinate coordination at the titanium atom, with bonding to two amido nitrogens and a chlorine as well as a secondary interaction to a flanking aryl ring of a terphenyl substituent. Compound 2 displays a very distorted four-coordinate metal environment in which the titanium atom is bound to two amido nitrogens and to two carbons from a terphenyl aryl ring. This structure is in sharp contrast to the expected two-coordinate linear structure that was observed in its first row metal (V–Ni) analogues. Magnetic studies confirm a d1 electron configuration for 1 but indicate that Ti{N(H)AriPr6}2 (2) is diamagnetic at ambient temperature consistent with the oxidation of titanium to Ti(IV). The different structure of 2 is attributed to the high reducing tendency of the Ti(II) in comparison to the other metals.
Co-reporter:Chun-Yi Lin ; Jing-Dong Guo ; James C. Fettinger ; Shigeru Nagase ; Fernande Grandjean ; Gary J. Long ; Nicholas F. Chilton
Inorganic Chemistry 2013 Volume 52(Issue 23) pp:13584-13593
Publication Date(Web):November 18, 2013
DOI:10.1021/ic402105m
A series of high spin, two-coordinate first row transition metal–amido complexes, M{N(SiMe3)Dipp}2 {M = Fe (1), Co (2), or Ni (3); Dipp = C6H3-2,6-Pri2} and a tetranuclear C–H activated chromium amide, [Cr{N(SiMe2CH2)Dipp}2Cr]2(THF) (4), were synthesized by reaction of their respective metal dihalides with 2 equiv of the lithium amide salt. They were characterized by X-ray crystallography, electronic and infrared spectroscopy, SQUID magnetic measurements, and computational methods. Contrary to steric considerations, the structures of 1–3 display planar eclipsed M{NSiC(ipso)}2 arrays and short M–N distances. DFT calculations, corrected for dispersion effects, show that dispersion interactions involving C–H–H–C moieties likely stabilize the structures by 21.1–29.4 kcal mol–1, depending on the level of the calculations employed. SQUID measurements confirm high spin electron configurations for all the complexes and substantial orbital contributions for 1 and 2.
Co-reporter:Aimee M. Bryan ; Gary J. Long ; Fernande Grandjean
Inorganic Chemistry 2013 Volume 52(Issue 20) pp:12152-12160
Publication Date(Web):October 10, 2013
DOI:10.1021/ic402019w
The synthesis, magnetic, and spectroscopic characteristics of the synthetically useful dimeric cobalt(II) silylamide complex [Co{N(SiMe3)2}2]2 (1) and several of its Lewis base complexes have been investigated. Variable-temperature nuclear magnetic resonance (NMR) spectroscopy of 1 showed that it exists in a monomer–dimer equilibrium in benzene solution and has an association energy (ΔGreacn) of −0.30(20) kcal mol–1 at 300 K. Magnetic data for the polycrystalline, red-brown [Co{N(SiMe3)2}2]2 (1) showed that it displays strong antiferromagnetic exchange coupling, expressed as −2JexS1S2, between the two S = 3/2 cobalt(II) centers with a Jex value of −215(5) cm–1, which is consistent with its bridged dimeric structure in the solid state. The electronic spectrum of 1 in solution is reported for the first time, and it is shown that earlier reports of the melting point, synthesis, electronic spectrum, and magnetic studies of the monomer “Co{N(SiMe3)2}2” are consistent with those of the bright green-colored tetrahydrofuran (THF) complex [Co{N(SiMe3)2}2(THF)] (4). Treatment of 1 with various Lewis bases yielded monomeric three-coordinated species—[Co{N(SiMe3)2}2(PMe3)] (2), and [Co{N(SiMe3)2}2(THF)] (4), as well as the previously reported [Co{N(SiMe3)2}2(py)] (3)—and the four-coordinated species [Co{N(SiMe3)2}2(py)2] (5) in good yields. The paramagnetic complexes 2–4 were characterized by electronic and 1H NMR spectroscopy, and by X-ray crystallography in the case of 2 and 4. Magnetic studies of 2–5 and of the known three-coordinated cobalt(II) species [Na(12-crown-4)2][Co{N(SiMe3)2}3] (6) showed that they have considerably larger χMT products and, hence, magnetic moments, than the spin-only values of 1.875 emu K mol–1 and 3.87 μB, which is indicative of a significant zero-field splitting and g-tensor anisotropy resulting from the pseudo-trigonal crystal field. A fit of χMT for 2–6 yields a large g-tensor anisotropy, large negative D-values (between −62 cm–1 and −82 cm–1), and E-values between ±10 cm–1 and ±21 cm–1.
Mechanisms of Reactions of Open-Shell, Heavier Group 14 Derivatives with Small Molecules: n−π* Back-Bonding in Isocyanide Complexes, C–H Activation under Ambient Conditions, CO Coupling, and Ancillary Molecular Interactions††This Award Article summarizes, including more recent results, one of the themes of a lecture presented on March 26th, 2012, at the 243rd Chemical Society National Meeting American in San Diego, CA, in receipt of the 2012 Award in Organometallic Chemistry sponsored by the Dow...
Co-reporter:Zachary D. Brown and Philip P. Power
Inorganic Chemistry 2013 Volume 52(Issue 11) pp:6248-6259
Publication Date(Web):May 17, 2013
DOI:10.1021/ic4007058
The main themes of this review are the mechanisms of the reactions of germanium and tin analogues of carbenes with isocyanides, CO, ammonia, and related molecules. The treatment of Ge(ArMe6)2 (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2) with MeNC or ButNC afforded 1:1 complexes, but the increase in the electron density at germanium leads to C–H activation at the isocyanide methyl or tert-butyl substituents. For MeNC, the initial adduct formation is followed by a migratory insertion of the MeNC carbon into a Ge–C(ipso) bond of an aryl substituent. The addition of excess MeNC led to sequential insertions of two further MeNC molecules. The third insertion led to methylisocyanide methyl group C–H activation, to afford an azagermacyclopentadienyl species. The ButNC complex (ArMe6)2GeCNBut spontanously transforms into (ArMe6)2Ge(H)CN and isobutene with C–H activation of the But substituent. The germylene Ge(ArMe6)(ArPri4) [ArPri4 = C6H3-2,6(C6H3-2,6-Pri2)2] reacted with CO to afford α-germyloxyketones. The initial step is the formation of a 1:1 complex, followed by migratory insertion into the Ge–C bond of the ArPri4 ligand to give ArMe6GeC(O)ArPri4. Insertion of a second CO gave ArMe6GeC(O)C(O)ArPri4, which rearranges to afford α-germyloxyketone. No reaction was observed for Sn(ArMe6)2 with RNC (R = Me, But) or CO. Spectroscopic (IR) results and density functional theory (DFT) calculations showed that the reactivity can be rationalized on the basis of Ge–C (isocyanide or CO) Ge(n) → π* (ligand) back-bonding. The reaction of Ge(ArMe6)2 and Sn(ArMe6)2 with ammonia or hydrazines initially gave 1:1 adducts. However, DFT calculations show that there are ancillary N–H---N interactions with a second ammonia or hydrazine, which stabilizes the transition state to form germanium(IV) hydride (amido or hydrazido) products. For tin, arene elimination is favored by a buildup of electron density at the tin, as well as the greater polarity of the Sn–C(ipso) bond. Germanium(IV) products were observed upon reaction of Ge(ArMe6)2 with acids, whereas reactions of Sn(ArMe6)2 with acids did not give tin(II) products. In contrast to reactions with NH3, there is no buildup of negative charge at tin upon protonation, and its subsequent reaction with conjugate bases readily affords the tin(IV) products.
Co-reporter:Oracio Serrano, James C. Fettinger, Philip P. Power
Polyhedron 2013 Volume 58() pp:144-150
Publication Date(Web):13 July 2013
DOI:10.1016/j.poly.2012.08.039
The reaction of LiArMe6 [ArMe6C6H3-2,6(C6H2-2,4,6-Me3)2] with InCl, [In(InI4)], InCl in the presence of LiI, or ‘GaI’ in toluene solution resulted in the isolation of the 1,2-diaryl-1,2-dihalogen derivatives [{InCl(ArMe6)}2]2 (1), [{InI(ArMe6)}2]2 (2), [{In4Cl2I2(ArMe6)4}] (3), and [{GaI(ArMe6)}2] (4). The indium derivatives 1–3 were isolated as tetrametallic complexes formed via the almost symmetric bridging by four halides of two In–In bonded, ArMe6In–InArMe6 moieties. In 1, the In4Cl4 core features almost parallel In–In units, linked by four almost symmetrically bridging chlorides. This yields a structure formed from two folded In2Cl2 rings, and two six-membered In4Cl2 boat-shaped rings that have common In–Cl edges. The structures of 2 and 3 also feature two ArMe6InInArMe6 units bridged by four halides. However, there is a large torsion angle between the two In–In vectors, so that the In4I4 (2) and In4Cl2I2 (3) cores are formed from four five-membered In3I2 (2) or In3ClI (3) rings. Compound 4 has a simple Ga–Ga bonded dimeric structure, in which the gallium atoms are three coordinated, being bonded to each other as well as to an iodine and an ArMe6 ligand. All the compounds were characterized by 1H and 13C {1H} NMR spectroscopy, and by X-ray crystallography. The structural differences between the gallium and indium derivatives is probably a result of the larger size and greater Lewis acidity of the indium centers.The associated 1,2-dihalo-1,2-diaryl diindium(I) dimeric compounds shown in the drawing, in which the indiums are four coordinate, have different structures for the chloride and iodide salts. In contrast, the corresponding 1,2-diiodo-1,2-diaryl digallium(II) compound is monomeric with three coordinated gallium atoms.
Co-reporter:Akseli Mansikkamäki, Philip P. Power, and Heikki M. Tuononen
Organometallics 2013 Volume 32(Issue 22) pp:6690-6700
Publication Date(Web):August 28, 2013
DOI:10.1021/om400558e
A detailed computational investigation of orbital interactions in metal–carbon bonds of metallylene–isocyanide adducts of the type R2MCNR′ (M = Si, Ge, Sn; R, R′ = alkyl, aryl) was performed using density functional theory and different methods based on energy decomposition analysis. Similar analyses have not been carried out before for metal complexes of isocyanides, even though the related carbonyl complexes have been under intense investigations throughout the years. The results of our work reveal that the relative importance of π-type back-bonding interactions in these systems increases in the sequence Sn < Ge ≪ Si, and in contrast to some earlier assumptions, the π-component cannot be neglected for any of the systems investigated. While the fundamental ligand properties of isocyanides are very similar to those of carbonyl, there are significant variations in the magnitudes of different effects observed. Most notably, on coordination to metals, both ligands can display positive or negative shifts in their characteristic stretching frequencies. However, because isocyanides are stronger σ donors, the metal-induced changes in the CN bonding framework are greater than those observed for carbonyl. Consequently, isocyanides readily exhibit positive CN stretching frequency shifts even in complexes where they function as π-acceptors, and the sign of these shifts is alone a poor indicator of the nature of the metal–carbon interaction. On the other hand, the relative π-character of the metal–carbon bond in metallylene–isocyanide adducts, as judged by the natural orbitals of chemical valence as well as by partitions of the orbital interaction energy, was shown to have a linear correlation with the shift in CN stretching frequency upon complex formation. The details of this correlation show that π-back-donation contributions to total orbital interaction energy need to exceed 100 kJ mol–1 in order for the shift in the CN stretching frequency of metallylene–isocyanide adducts to be negative.
Co-reporter:Xiaoyu Chen;Dr. Xingyong Wang;Zhaoyi Zhou; Yizhi Li;Yunxia Sui; Jing Ma; Xinping Wang; Philip P. Power
Angewandte Chemie International Edition 2013 Volume 52( Issue 2) pp:589-592
Publication Date(Web):
DOI:10.1002/anie.201207412
Co-reporter:Philip P. Power
Chemical Reviews 2012 Volume 112(Issue 6) pp:3482
Publication Date(Web):April 5, 2012
DOI:10.1021/cr2004647
Co-reporter:Christine A. Caputo ; Jing-Dong Guo ; Shigeru Nagase ; James C. Fettinger
Journal of the American Chemical Society 2012 Volume 134(Issue 16) pp:7155-7164
Publication Date(Web):March 15, 2012
DOI:10.1021/ja301247h
The heavier group 13 element alkene analogue, digallene AriPr4GaGaAriPr4 (1) [AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2], has been shown to react readily in [n + 2] (n = 6, 4, 2 + 2) cycloaddition reactions with norbornadiene and quadricyclane, 1,3,5,7-cyclooctatetraene, 1,3-cyclopentadiene, and 1,3,5-cycloheptatriene to afford the heavier element deltacyclane species AriPr4Ga(C7H8)GaAriPr4 (2), pseudoinverse sandwiches AriPr4Ga(C8H8)GaAriPr4 (3, 3iso), and polycyclic compounds AriPr4Ga(C5H6)GaAriPr4 (4) and AriPr4Ga(C7H8)GaAriPr4 (5, 5iso), respectively, under ambient conditions. These reactions are facile and may be contrasted with other all-carbon versions, which require transition-metal catalysis or forcing conditions (temperature, pressure), or with the reactions of the corresponding heavier group 14 species AriPr4EEAriPr4 (E = Ge, Sn), which give very different product structures. We discuss several mechanistic possibilities, including radical- and non-radical-mediated cyclization pathways. These mechanisms are consistent with the improved energetic accessibility of the LUMO of the heavier group 13 element multiple bond in comparison with that of a simple alkene or alkyne. We show that the calculated frontier molecular orbitals (FMOs) of AriPr4GaGaAriPr4 are of π–π symmetry, allowing this molecule to engage in a wider range of reactions than permitted by the usual π–π* FMOs of C–C π bonds or the π–n+ FMOs of heavier group 14 alkyne analogues.
Co-reporter:Zachary D. Brown ; Petra Vasko ; James C. Fettinger ; Heikki M. Tuononen
Journal of the American Chemical Society 2012 Volume 134(Issue 9) pp:4045-4048
Publication Date(Web):February 13, 2012
DOI:10.1021/ja211874u
Reaction of the diarylgermylene Ge(ArMe6)2 [ArMe6 = C6H3-2,6-(C6H2-2,4,6-(CH3)3)2] with tert-butyl isocyanide gave the Lewis adduct species (ArMe6)2GeCNBut, in which the isocyanide ligand displays a decreased C–N stretching frequency consistent with an n → π* back-bonding interaction. Density functional theory confirmed that the HOMO is a Ge–C bonding combination between the lone pair of electrons on the germanium atom and the C–N π* orbital of the isocyanide ligand. The complex undergoes facile C–H bond activation to produce a new diarylgermanium hydride/cyanide species and isobutene via heterolytic cleavage of the N–But bond.
Co-reporter:Owen T. Summerscales ; Christine A. Caputo ; Caroline E. Knapp ; James C. Fettinger
Journal of the American Chemical Society 2012 Volume 134(Issue 35) pp:14595-14603
Publication Date(Web):August 23, 2012
DOI:10.1021/ja305853d
Formally, triple-bonded dimetallynes ArEEAr [E = Ge (1), Sn (2); Ar = C6H3-2,6-(C6H3-2,6-iPr2)2] have been previously shown to activate aliphatic, allylic C–H bonds in cyclic olefins, cyclopentadiene (CpH), cyclopentene (c-C5H8) and 1,4-cyclohexadiene, with intriguing selectivity. In the case of the five-membered carbocycles, cyclopentadienyl species ArECp [E = Ge (3), Sn (4)] are formed. In this study, we examine the mechanisms for activation of CpH and c-C5H8 using experimental methods and describe a new product found from the reaction between 1 and c-C5H8, an asymmetrically substituted digermene ArGe(H)Ge(c-C5H9)Ar (5), crystallized in 46% yield. This compound contains a hydrogenated cyclopentyl moiety and is found to be produced in a 3:2 ratio with 3, explaining the fate of the liberated H atoms following triple C–H activation. We show that when these C–H activation reactions are carried out in the presence of tert-butyl ethylene (excess), compounds {ArE(CH2CH2tBu)}2 [E = Ge(8), Sn(9)] are obtained in addition to ArECp; in the case of CpH, the neohexyl complexes replace the production of H2 gas, and for c-C5H8 they displace cyclopentyl product 5 and account for all the hydrogen removed in the dehydroaromatization reactions. To confirm the source of 8 and 9, it was demonstrated that these molecules are formed cleanly between the reaction of (ArEH)2 [E = Ge(6), Sn(7)] and tert-butyl ethylene, new examples of noncatalyzed hydro-germylation and -stannylation. Therefore, the presence of transient hydrides of the type 6 and 7 can be surmised to be reactive intermediates in the production of 3 and 4, along with H2, from 1 and 2 and CpH (respectively), or the formation of 3 and 5 from 1. The reaction of 6 or 7 with CpH gave 3 or 4, respectively, with concomitant H2 evolution, demonstrating the basic nature of these low-valent group 14 element hydrides and their key role in the ‘cascade’ of C–H activation steps. Additionally, during the course of these studies a new polycyclic compound (ArGe)2(C7H12) (10) was obtained in 60% yield from the reaction of 1,6-heptadiene and 1 via double [2 + 2] cycloaddition and gives evidence for a nonradical mechanism for these types of reactions.
Co-reporter:Mario Carrasco, Michelle Faust, Riccardo Peloso, Amor Rodríguez, Joaquín López-Serrano, Eleuterio Álvarez, Celia Maya, Philip P. Power and Ernesto Carmona
Chemical Communications 2012 vol. 48(Issue 33) pp:3954-3956
Publication Date(Web):28 Feb 2012
DOI:10.1039/C2CC30394A
New quadruply bonded dimolybdenum complexes of the terphenyl ligand ArXyl2 (ArXyl2 = C6H3-2,6-(C6H3-2,6-Me2)2) have been prepared and structurally characterized. The steric hindrance exerted by the ArXyl2 groups causes the Mo atoms to feature unsaturated four-coordinate structures and a formal fourteen-electron count.
Co-reporter:Aimee M. Bryan, W. Alexander Merrill, William M. Reiff, James C. Fettinger, and Philip P. Power
Inorganic Chemistry 2012 Volume 51(Issue 6) pp:3366-3373
Publication Date(Web):February 24, 2012
DOI:10.1021/ic2012414
The complexes M(II){N(H)ArPri6}2 (M = Co, 1 or Ni, 2; ArPri6 = C6H3-2,6(C6H2-2,4,6-Pri3)2), which have rigorously linear, N–M–N = 180°, metal coordination, and M(II){N(H)ArMe6}2 (M = Co, 3 or Ni, 4; ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2), which have bent, N–Co–N = 144.1(4)°, and N–Ni–N = 154.60(14)°, metal coordination, were synthesized and characterized to study the effects of the metal coordination geometries on their magnetic properties. The magnetometry studies show that the linear cobalt(II) species 1 has a very high ambient temperature moment of about 6.2 μB (cf. spin only value = 3.87 μB) whereas the bent cobalt species 3 had a lower μB value of about 4.7 μB. In contrast, both the linear and the bent nickel complexes 2 and 4 have magnetic moments near 3.0 μB at ambient temperatures, which is close to the spin only value of 2.83 μB. The studies suggest that in the linear cobalt species 1 there is a very strong enhanced spin orbital coupling which leads to magnetic moments that broach the free ion value of 6.63 μB probably as a result of the relatively weak ligand field and its rigorously linear coordination. For the linear nickel species 2, however, the expected strong first order orbital angular momentum contribution does not occur (cf. free ion value 5.6 μB) possibly because of π bonding effects involving the nitrogen p orbitals and the dxz and dyz orbitals (whose degeneracy is lifted in the C2h local symmetry of the Ni{N(H)C(ipso)}2 array) which quench the orbital angular momentum.
Co-reporter:Jessica N. Boynton ; W. Alexander Merrill ; William M. Reiff ; James C. Fettinger
Inorganic Chemistry 2012 Volume 51(Issue 5) pp:3212-3219
Publication Date(Web):February 22, 2012
DOI:10.1021/ic202661n
The synthesis and characterization of the mononuclear chromium(II) terphenyl substituted primary amido-complexes Cr{N(H)ArPri6}2 (ArPri6 = C6H3-2,6-(C6H2-2,4,6-iPr3)2 (1), Cr{N(H)ArPri4}2 (ArPri4 = C6H3-2,6-(C6H3-2,6-iPr2)2 (2), Cr{N(H)ArMe6}2 (ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2 (4), and the Lewis base adduct Cr{N(H)ArMe6}2(THF) (3) are described. Reaction of the terphenyl primary amido lithium derivatives Li{N(H)ArPri6} and Li{N(H)ArPri4} with CrCl2(THF)2 in a 2:1 ratio afforded complexes 1 and 2, which are extremely rare examples of two coordinate chromium and the first stable chromium amides to have linear coordinated high-spin Cr2+. The reaction of the less crowded terphenyl primary amido lithium salt Li{N(H)ArMe6} with CrCl2(THF)2 gave the tetrahydrofuran (THF) complex 3, which has a distorted T-shaped metal coordination. Desolvation of 3 at about 70 °C gave 4 which has a formally two-coordinate chromous ion with a very strongly bent core geometry (N–Cr–N= 121.49(13)°) with secondary Cr--C(aryl ring) interactions of 2.338(4) Å to the ligand. Magnetometry studies showed that the two linear chromium species 1 and 2 have ambient temperature magnetic moments of about 4.20 μB and 4.33 μB which are lower than the spin-only value of 4.90 μB typically observed for six coordinate Cr2+. The bent complex 4 has a similar room temperature magnetic moment of about 4.36 μB. These studies suggest that the two-coordinate chromium complexes have significant spin–orbit coupling effects which lead to moments lower than the spin only value of 4.90 μB because λ (the spin orbit coupling parameter) is positive. The three-coordinated complex 3 had a magnetic moment of 3.79 μB.
Co-reporter:Hao Lei, James C. Fettinger, and Philip P. Power
Inorganic Chemistry 2012 Volume 51(Issue 3) pp:1821-1826
Publication Date(Web):January 19, 2012
DOI:10.1021/ic202116s
Reduction of [(3,5-iPr2-Ar*)Co(μ-Cl)]2 (3,5-iPr2-Ar* = -C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2) with KC8 in the presence of various arene molecules resulted in the formation of a series of terphenyl stabilized Co(I) half-sandwich complexes (3,5-iPr2-Ar*)Co(η6-arene) (arene = toluene (1), benzene (2), C6H5F (3)). X-ray crystallographic studies revealed that the three compounds adopt similar bonding schemes but that the fluorine-substituted derivative 3 shows the strongest cobalt-η6-arene interaction. In contrast, C–F bond cleavage occurred when the analogous reduction was conducted in the presence of C6F6, affording the salt K[(3,5-iPr2-Ar*)Co(F)(C6F5)] (4), in which there is a three-coordinate cobalt complexed by a fluorine atom, a C6F5 group, and the terphenyl ligand Ar*-3,5-iPr2. This salt resulted from the formal insertion of a putative 3,5-iPr2-Ar*Co species as a neutral or anionic moiety into one of the C–F bonds of C6F6. Reduction of [(3,5-iPr2-Ar*)Co(μ-Cl)]2 in the presence of bulkier substituted benzene derivatives such as mesitylene, hexamethylbenzene, tert-butylbenzene, or 1,3,5-triisopropylbenzene did not afford characterizable products.
Co-reporter:Jessica N. Boynton, Owen T. Summerscales, Fernande Grandjean, Gary J. Long, James C. Fettinger, and Philip P. Power
Organometallics 2012 Volume 31(Issue 24) pp:8556-8560
Publication Date(Web):December 3, 2012
DOI:10.1021/om300936s
Reaction of K2COT (COT = 1,3,5,7-cyclooctatetraene, C8H8) with the aryl chromium(II) halide [AriPr4Cr(μ-Cl)]2 (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) gave (CrAriPr4)2(μ2-η3:η4-COT) (1), in which a nonplanar COT ring is complexed between two CrAriPr4 moieties, a configuration previously unknown for chromium complexes of COT. One Cr2+ ion is bonded primarily to three COT carbons (Cr–C = 2.22–2.30 Å) as well as an ipso carbon (Cr–C ≈ 2.47 Å) from a flanking aryl ring of its terphenyl substituent. The other Cr2+ ion bonds to an ipso carbon (Cr–C ≈ 2.53 Å) from its terphenyl substituent as well as four COT carbons (Cr–C = 2.24–2.32 Å). The COT carbon–carbon distances display an alternating pattern, consistent with the nonplanarity and nonaromatic character of the ring. The magnetic properties of 1 indicate that the Cr2+ ions have a high-spin d4 configuration with S = 2. The temperature dependence of the magnetism indicates that their behavior is due to zero-field splitting of the S = 2 state. Attempts to prepare 1 by the direct reaction of quintuple-bonded (CrAriPr4)2 with COT were unsuccessful.
Co-reporter:Philip P. Power
The Chemical Record 2012 Volume 12( Issue 2) pp:238-255
Publication Date(Web):
DOI:10.1002/tcr.201100016
Abstract
The first reaction between hydrogen and a main-group compound under ambient conditions was reported in 2005. This unexpected result has been followed by numerous others which show that such reactivity is widespread in unsaturated and multiple bonded main-group species. These may react spontaneously not only with hydrogen, but also with ethylene, ammonia and related molecules. This account focuses on results from the author's laboratory but also on parallel work by other groups. The link between HOMO-LUMO separations, symmetry considerations and reactivity of the main-group species is emphasized as is their similarity in reactivity to transition-metal organometallic compounds.DOI 10.1002/tcr.201100016
Co-reporter:Philip P. Power
Accounts of Chemical Research 2011 Volume 44(Issue 8) pp:627
Publication Date(Web):June 10, 2011
DOI:10.1021/ar2000875
We showed in 2005 that a digermyne, a main group compound with a digermanium core and aromatic substituents, reacted directly with hydrogen at 25 °C and 1 atm to give well-defined hydrogen addition products. This was the first report of a reaction of main group molecules with hydrogen under ambient conditions. Our group and a number of others have since shown that several classes of main group molecules, either alone or in combination, react directly (in some cases reversibly) with hydrogen under mild conditions. Moreover, this reactivity was not limited to hydrogen but also included direct reactions with other important small molecules, including ammonia, boranes, and unactivated olefins such as ethylene. These reactions were largely unanticipated because main group species were generally considered to be too unreactive to effect such transformations.In this Account, we summarize recent developments in the reactions of the multiple bonded and other open shell derivatives of the heavier main group elements with hydrogen, ammonia, olefins, or related molecules. We focus on results generated primarily in our laboratory, which are placed in the context of parallel findings by other researchers. The close relationship between HOMO–LUMO separations, symmetry considerations, and reactivity of the open shell in main group compounds is emphasized, as is their similarity in reactivity to transition metal organometallic compounds.The unexpectedly potent reactivity of the heavier main group species arises from the large differences in bonding between the light and heavy elements. Specifically, the energy levels within the heavier element molecules are separated by much smaller gaps as a result of generally lower bond strengths. In addition, the ordering and symmetries of the energy levels are generally different for their light counterparts. Such differences lie at the heart of the new reactions. Moreover, the reactivity of the molecules can often be interpreted qualitatively in terms of simple molecular orbital considerations. More quantitative explanations are accessible from increasingly sophisticated density functional theory (DFT) calculations.We open with a short description of the background developments that led to this work. These advances involved the synthesis and characterization of numerous new main group molecules involving multiple bonds or unsaturated configurations; they were pursued over the latter part of the last century and the beginning of the new one. The results firmly established that the structures and bonding in the new compounds differed markedly from those of their lighter element congeners. The knowledge gained from this fundamental work provided the framework for an understanding of their structures and bonding, and hence an understanding of the reactivity of the compounds discussed here.
Co-reporter:Owen T. Summerscales ; James C. Fettinger
Journal of the American Chemical Society 2011 Volume 133(Issue 31) pp:11960-11963
Publication Date(Web):July 12, 2011
DOI:10.1021/ja205816d
Treatment of the dimetallynes Ar′EEAr′ [E = Ge, Sn; Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2] with a cyclic olefin—cyclopentadiene (CpH), cyclopentene, 1,4-cyclohexadiene (CHD), or cyclohexene—showed that, with the exception of cyclohexene, they react readily, affording C–H activation at room temperature. Reaction of the digermyne and distannyne with CpH gave the cyclopentadienyl anion, which is bound in a π-fashion to a mononuclear group 14 element center, along with evolution of hydrogen gas. Unusually, the digermyne also reacted with cyclopentene to give the same dehydroaromatization product, formed from triple C–H activation/dehydrogenation. It also was found to react with CHD to give a mixture of (Ar′GeH)2, benzene, and a new 7-germanorbornadiene species bound to a cyclohex-2-enyl fragment.
Co-reporter:Christine A. Caputo, Zhongliang Zhu, Zachary D. Brown, James C. Fettinger and Philip P. Power
Chemical Communications 2011 vol. 47(Issue 26) pp:7506-7508
Publication Date(Web):31 May 2011
DOI:10.1039/C1CC11676B
The reactions of Ar′GaGaAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) with alkenes revealed the addition of two olefins per Ar′GaGaAr′ under ambient conditions for ethylene, propene, 1-hexene and styrene but no reactions with more hindered or cyclic olefins.
Co-reporter:Philip P. Power and François Pierre Gabbaı̈
Inorganic Chemistry 2011 Volume 50(Issue 24) pp:12221-12222
Publication Date(Web):November 28, 2011
DOI:10.1021/ic2023049
Co-reporter:Krishna K. Pandey, Pankaj Patidar, and Philip P. Power
Inorganic Chemistry 2011 Volume 50(Issue 15) pp:7080-7089
Publication Date(Web):June 23, 2011
DOI:10.1021/ic2005908
The molecular and electronic structures and bonding analysis of terminal cationic metal–ylyne complexes (MeCN)(PMe3)4M≡EMes]+ (M = Mo, W; E = Si, Ge, Sn, Pb) were investigated using DFT/BP86/TZ2P/ZORA level of theory. The calculated geometrical parameters for the model complexes are in good agreement with the reported experimental values. The M–E σ-bonding orbitals are slightly polarized toward E except in the complex [(MeCN)(PMe3)4W(SnMes)]+, where the M–E σ-bonding orbital is slightly polarized toward the W atom. The M–E π-bonding orbitals are highly polarized toward the metal atom. In all complexes, the π-bonding contribution to the total M≡EMes bond is greater than that of the σ-bonding contribution and increases upon going from M = Mo to W. The values of orbital interaction ΔEorb are significantly larger in all studied complexes I–VIII than the electrostatic interaction ΔEelstat. The absolute values of the interaction energy, as well as the bond dissociation energy, decrease in the order Si > Ge > Sn > Pb, and the tungsten complexes have stronger bonding than the molybdenum complexes.
Co-reporter:Hao Lei, Jing-Dong Guo, James C. Fettinger, Shigeru Nagase, and Philip P. Power
Organometallics 2011 Volume 30(Issue 22) pp:6316-6322
Publication Date(Web):November 3, 2011
DOI:10.1021/om200912x
The reactions of [ArE(Cl)]2 (E = Ge, Sn; Ar = −C6H3-2,6-(C6H3-2,6-iPr2)2 (ArPri4), −C6H3-2,6-(C6H2-2,4,6-iPr3)2 (ArPri6)) with K[(η5-C5H5)Fe(CO)2] afforded the deep green ferriogermylenes ArGeFe(η5-C5H5)(CO)2 (Ar = ArPri4 (1), ArPri6 (2)) and the ferriostannylenes ArSnFe(η5-C5H5)(CO)2 (Ar = ArPri4 (3), ArPri6 (4)), respectively. Complexes 1–4 were characterized by NMR, UV–vis, and IR spectroscopy, as well as by X-ray crystallography. The solid-state structures of 1–4 feature two-coordinate Ge or Sn atoms with bent C–E–Fe (E = Ge, Sn) geometries. Although germylenes 1 and 2 remain intact upon heating or UV irradiation, stannylenes 3 and 4 were shown to eliminate one carbonyl group upon exposure to UV light, affording the brown dimeric species {ArSnFe(η5-C5H5)(CO)}2 (Ar = ArPri4 (5), ArPri6 (6)), respectively.
Co-reporter:Owen T. Summerscales, Marilyn M. Olmstead, and Philip P. Power
Organometallics 2011 Volume 30(Issue 13) pp:3468-3471
Publication Date(Web):June 7, 2011
DOI:10.1021/om2004018
Ditetryldiyl ethers (Ar′E)2(μ-O) (E = Ge, Sn; Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) which contain a pair of two-coordinate Sn or Ge atoms were successfully prepared by the reaction of the corresponding dimetallylene (Ar′E)2 with 1 equiv of pyridine N-oxide. The tin oxide was found to cocrystallize with a hydroxide impurity: {Ar′Sn(μ-OH)}2. Structural determination revealed a slightly bent oxide E–O–E core (E = Ge, 154.8(1)°; E = Sn, 154.7(3)°) and a trans orientation of the Ar′ groups in each complex. The compounds were also characterized by NMR and electronic spectroscopy.
Co-reporter: Xinping Wang; Philip P. Power
Angewandte Chemie International Edition 2011 Volume 50( Issue 46) pp:10965-10968
Publication Date(Web):
DOI:10.1002/anie.201103904
Co-reporter:Oracio Serrano, Elke Hoppe, James C. Fettinger, Philip P. Power
Journal of Organometallic Chemistry 2011 696(10) pp: 2217-2219
Publication Date(Web):
DOI:10.1016/j.jorganchem.2010.11.043
Co-reporter:Roland C. Fischer and Philip P. Power
Chemical Reviews 2010 Volume 110(Issue 7) pp:3877
Publication Date(Web):July 14, 2010
DOI:10.1021/cr100133q
Co-reporter:Owen T. Summerscales ; J. Oscar C. Jiménez-Halla ; Gabriel Merino
Journal of the American Chemical Society 2010 Volume 133(Issue 2) pp:180-183
Publication Date(Web):December 14, 2010
DOI:10.1021/ja107380p
Reaction of a digermyne with cyclooctatetraene (cot) gave two isomeric products. A Ge(II) inverse sandwich is formed as the kinetic product, which was a result of complete Ge≡Ge bond cleavage and the formation of a π-bound cot ring. This isomerized in solution at room temperature over a period of 5 days to give the thermodynamic product, a tetracyclic diene-digermane, in which a single-bonded Ge—Ge moiety has inserted into a C═C bond of the cot carbocycle. Kinetic studies afforded an activation enthalpy (ΔH‡) and entropy (ΔS‡) of 14.9 kcal mol−1 and −6.2 cal mol−1 K−1 respectively. Heating crystals of the thermodynamic product at ca. 120 °C cleanly regenerated the original inverse sandwich isomer.
Co-reporter:Hao Lei ; Jing-Dong Guo ; James C. Fettinger ; Shigeru Nagase
Journal of the American Chemical Society 2010 Volume 132(Issue 49) pp:17399-17401
Publication Date(Web):November 19, 2010
DOI:10.1021/ja1089777
A series of first row transition metal complexes with unsupported M−Fe bonds, (3,5-iPr2-Ar*)MFe(η5-C5H5)(CO)2 (M = Fe (1), Mn (2), Cr (3), 3,5-iPr2-Ar* = -C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2), was synthesized by salt metathesis. They were characterized by 1H NMR, UV−vis spectroscopy, X-ray crystallography, and SQUID magnetic measurements. Two distinct Fe atoms in 1 were confirmed by Mössbauer spectroscopy. All three compounds feature short metal−metal bond distances (Fe−Fe, 2.3931(8) Å (1); Mn−Fe, 2.4512(5) Å (2); Cr−Fe, 2.4887(5) Å (3)). Their DFT computed structures were in excellent agreement with the experimental data and revealed a dative bonding interaction between the metals.
Co-reporter:Xinping Wang ; Yang Peng ; Marilyn M. Olmstead ; Håkon Hope
Journal of the American Chemical Society 2010 Volume 132(Issue 38) pp:13150-13151
Publication Date(Web):September 1, 2010
DOI:10.1021/ja1051236
The reaction of a digermyne Ar′GeGeAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2) with AgSbF6 at −40 °C forms the complex (AgAr′GeGeAr′)+SbF6−, which provides the first example of a heavier group 14 element alkyne analogue behaving as a π donor to a transition metal. The cation (AgAr′GeGeAr′)+ is best described as a hybrid of a π-complex and a σ-metallacyclopropene structure.
Co-reporter:Yang Peng, Roland C. Fischer, W. Alexander Merrill, Jelena Fischer, Lihung Pu, Bobby D. Ellis, James C. Fettinger, Rolfe H. Herber and Philip P. Power
Chemical Science 2010 vol. 1(Issue 4) pp:461-468
Publication Date(Web):18 Jun 2010
DOI:10.1039/C0SC00240B
The synthesis and characterization of a series of digermynes and distannynes stabilized by terphenyl ligands are described. The ligands are based on the Ar′ (Ar′ = C6H3-2,6(C6H3-2,6-iPr2)2) or Ar* (Ar* = C6H3-2,6(C6H2-2,4,6-iPr3)2) platforms which were modified at the meta or para positions of their central aryl rings to yield 4-X-Ar′ (4-X-Ar′ = 4-X-C6H2-2,6(C6H3-2,6-iPr2)2, X = H, F, Cl, OMe, tBu, SiMe3, GeMe3) and 3,5-iPr2-Ar′ or Ar* and 3,5-iPr2-Ar*. The compounds were synthesized by reduction of the terphenyl germanium(II) or tin(II) halide precursors with a variety of reducing agents. The precursors were obtained by the reaction of one equivalent of the lithium terphenyl with GeCl2 dioxane or SnCl2. For germanium, their X-ray crystal structures showed them to be either Ge–Ge bonded dimers with trans-pyramidal geometries or V-shaped monomers. In contrast, the terphenyl tin halides had no tin–tin bonding but existed either as halide bridged dimers or V-shaped monomers. Reduction with a variety of reducing agents afforded the digermynes ArGeGeAr (Ar = 4-Cl-Ar′, 4-SiMe3-Ar′ or 3,5-iPr2-Ar*) or the distannynes ArSnSnAr (Ar = 4-F-Ar′, 4-Cl-Ar′, 4-MeO-Ar′, 4-tBu-Ar′, 4-SiMe3-Ar′, 4-GeMe3-Ar′, 3,5-iPr2-Ar′, 3,5-iPr2-Ar*), which were characterized structurally and spectroscopically. The digermynes display planar trans-bent core geometries with Ge–Ge distances near 2.26 Å and bending angles near 128° consistent with Ge–Ge multiple bonding. In contrast, the distannynes had either multiple bonded geometries with Sn–Sn distances that averaged 2.65 Å and an average bending angle near 123.8°, or single bonded geometries with a Sn–Sn bond length near 3.06 Å and a bending angle near 98°. The 3,5-iPr2-Ar*SnSnAr*-3,5-iPr2 species had an intermediate structure with a longer multiple bond near 2.73 Å and a variable torsion angle (14–28°) between the tin coordination planes. Mössbauer data for the multiple and single bonded species displayed similar isomer shifts but had different quadrupole splittings.
Co-reporter:Andrew D. Sutton, Benjamin L. Davis, Koyel X. Bhattacharyya, Bobby D. Ellis, John C. Gordon and Philip P. Power
Chemical Communications 2010 vol. 46(Issue 1) pp:148-149
Publication Date(Web):13 Nov 2009
DOI:10.1039/B919383A
The use of benzenedithiol as a digestant for ammonia–borane spent fuel has been shown to result in tin thiolate compounds which we demonstrate can be recycled, yielding Bu3SnH and ortho-benzenedithiol for reintroduction to the ammonia–borane regeneration scheme.
Co-reporter:Yang Peng, Xinping Wang, James C. Fettinger and Philip P. Power
Chemical Communications 2010 vol. 46(Issue 6) pp:943-945
Publication Date(Web):08 Jan 2010
DOI:10.1039/B919828H
The reaction of the distannyne Ar′SnSnAr′ (Ar′ = C6H3-2,6(C6H3-2,6-iPr2)2) with tert-butyl or mesityl isocyanide afforded the bis-adducts Ar′SnSnAr′(CNBut)2 or Ar′SnSnAr′ (CNMes)2 in which the isonitriles are reversibly bound under ambient conditions.
Co-reporter:Chengbao Ni, Troy A. Stich, Gary J. Long and Philip P. Power
Chemical Communications 2010 vol. 46(Issue 25) pp:4466-4468
Publication Date(Web):20 May 2010
DOI:10.1039/C001483D
The synthesis and characterization of two-coordinate cobalt(II) complexes CoAr′2 (1) and Ar′CoN(SiMe3)2 (2) (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) are reported. The magnetic data for 2 show that it has an unexpectedly high μeff of 5.65 μB whereas the bent complex 1 has a significantly lower moment.
Co-reporter:W. Alexander Merrill ; Eric Rivard ; Jeffrey S. DeRopp ; Xinping Wang ; Bobby D. Ellis ; James C. Fettinger ; Bernd Wrackmeyer
Inorganic Chemistry 2010 Volume 49(Issue 18) pp:8481-8486
Publication Date(Web):August 24, 2010
DOI:10.1021/ic101068a
Reaction of M{N(SiMe3)2}2 (M = Ge, Sn, or Pb) with the sterically encumbered primary phosphine Ar′PH2 (2), Ar′ = C6H3-2,6-(C6H3-2,6-Pri2), at ca. 200 °C afforded the highly colored phosphinidene dimers {M(μ-PAr′)}2, M = Ge(3), Sn(4), or Pb(5), with disilylamine elimination. The compounds were characterized by single-crystal X-ray crystallography and heteronuclear NMR spectroscopy. The structures of 3, 4, and 5 featured similar M2P2 ring cores, of which 4 and 5 have 50/50 P atom disorder, consistent with either a planar four-membered M2P2 arrangement with anti aryl groups or with an M2P2 ring folded along the M−M axis with syn aryl groups. A syn-folded structure was resolved for the Ge2P2 ring in compound 3. The M−P distances resembled those in M(II) phosphido complexes and are consistent with single bonding. The coordination geometries at the phosphorus atoms are pyramidal. DFT calculations on the gas phase models {M(μ-PMe)}2 (M = Ge, Sn, Pb) agreed with the syn (M−M folded) structural interpretation of the X-ray data. The synthesis of the bulky phosphine Ar′PH2 2 with the use of the aryl transfer agent Ar′MgBr(THF)2 is also reported. This route afforded a significantly higher yield of product than that which was obtained using LiAr′, which tends to result in aryl halide elimination and the observation of insoluble red phosphorus.
Co-reporter:William A. Merrill ; Robert J. Wright ; Corneliu S. Stanciu ; Marilyn M. Olmstead ; James C. Fettinger
Inorganic Chemistry 2010 Volume 49(Issue 15) pp:7097-7105
Publication Date(Web):July 2, 2010
DOI:10.1021/ic100831c
The solvent-free reaction of M{N(SiMe3)2}2 (M = Ge, Sn, or Pb) with the sterically encumbered primary amine 2,6-dimesitylaniline Ar#NH2 [Ar# = C6H3-2,6(C6H2-2,4,6-Me3)2] at ca. 165−175 °C afforded the highly colored imido dimers {M(μ-NAr#)}2, where M = Ge (1), Sn (2), or Pb (3), with disilylamine elimination. The compounds were characterized by single-crystal X-ray crystallography and heteronuclear NMR spectroscopy. The structures of 1−3 were very similar and had nonplanar four-membered M2N2 ring cores that are folded along the M---M axis. The nitrogen atoms are planar-coordinated, and the M−N distances are consistent with single bonding. The reaction of M{N(SiMe3)2}2 with Ar#NH2 in a 2:1 ratio in solution at lower temperature afforded the relatively stable monomeric primary amido species M{N(H)Ar#}2, where M = Ge (4), Sn (5), or Pb (6). Complexes 4−6 displayed V-shaped MN2 structures, and 5 and 6 revealed close approaches between the metal atom and ipso-carbon atoms of two flanking Mes groups of the terphenyl substituents [SnII---C (2.957 Å) and PbII---C (2.965 Å)]. The secondary metal−ligand interactions exerted large effects on their electronic and NMR spectra.
Co-reporter:Chengbao Ni, James C. Fettinger, Gary J. Long and Philip P. Power
Dalton Transactions 2010 vol. 39(Issue 44) pp:10664-10670
Publication Date(Web):06 Oct 2010
DOI:10.1039/C0DT00771D
Reaction of {Li(THF)Ar′MnI2}2 (Ar′ = C6H3-2,6-(C6H2-2,6-iPr3)2) with LiAr′, LiCCR (R = tBu or Ph), or (C6H2-2,4,6-iPr3)MgBr(THF)2 afforded the diaryl MnAr′2 (1), the alkynyl salts Ar′Mn(CCtBu)4{Li(THF)}3 (2) and Ar′Mn(CCPh)3Li3(THF)(Et2O)2(μ3-I) (3), and the manganate salt {Li(THF)}Ar′Mn(μ-I)(C6H2-2,4,6-iPr3) (4), respectively. Complex 4 reacted with one equivalent of (C6H2-2,4,6-iPr3)MgBr(THF)2 to afford the homoleptic dimer {Mn(C6H2-2,4,6-iPr3)(μ-C6H2-2,4,6-iPr3)}2 (5), which resulted from the displacement of the bulkier Ar′ ligand in preference to the halogen. The reaction of the more crowded {Li(THF)Ar*MnI2}2 (Ar* = C6H3-2,6-(C6H2-2,4,6-iPr3)2) with LitBu gave complex Ar*MntBu (6). Complex 1 is a rare monomeric homoleptic two-coordinate diaryl Mn(II) complex; while 6 displays no tendency to eliminate β-hydrogens from the tBu group because of the stabilization supplied by Ar*. Compounds 2 and 3 have cubane frameworks, which are constructed from a manganese, three carbons from three acetylide ligands, three lithiums, each coordinated by a donor, plus either a carbon from a further acetylide ligand (2) or an iodide (3). The Mn(II) atom in 4 has an unusual distorted T-shaped geometry while the dimeric 5 features trigonal planar manganese coordination. The chloride substituted complex Li2(THF)3{Ar′MnCl2}2 (7), which has a structure very similar to that of {Li(THF)Ar′MnI2}2, was also prepared for use as a possible starting material. However, its generally lower solubility rendered it less useful than the iodo salt. Complexes 1–7 were characterized by X-ray crystallography and UV-vis spectroscopy. Magnetic studies of 2–4 and 6 showed that they have 3d5 high-spin configurations.
Co-reporter:OwenT. Summerscales Dr.;Xinping Wang Dr. ;PhilipP. Power
Angewandte Chemie International Edition 2010 Volume 49( Issue 28) pp:4788-4790
Publication Date(Web):
DOI:10.1002/anie.201001276
Co-reporter:Xinping Wang Dr.;Yang Peng;Zhongliang Zhu;JamesC. Fettinger Dr.;PhilipP. Power ;Jingdong Guo Dr.;Shigeru Nagase
Angewandte Chemie International Edition 2010 Volume 49( Issue 27) pp:4593-4597
Publication Date(Web):
DOI:10.1002/anie.201001086
Co-reporter:OwenT. Summerscales Dr.;Xinping Wang Dr. ;PhilipP. Power
Angewandte Chemie 2010 Volume 122( Issue 28) pp:4898-4900
Publication Date(Web):
DOI:10.1002/ange.201001276
Co-reporter:Hao Lei, James C. Fettinger, and Philip P. Power
Organometallics 2010 Volume 29(Issue 21) pp:5585-5590
Publication Date(Web):July 13, 2010
DOI:10.1021/om100492u
The reaction of (Ar′SnCl)2 (Ar′ = −C6H3-2,6-(C6H3-2,6-iPr2)2) with LiC≡CR (R = SiMe3 or tBu) afforded the orange-red, alkynyl-substituted, symmetric distannene Ar′(Me3SiC≡C)SnSn(C≡CSiMe3)Ar′ (1) or the blue unsymmetric stannylstannylene Ar′SnSn(C≡CtBu)2Ar′ (2), respectively, whose structures were determined by X-ray crystallography. In solution at room temperature, however, both compounds have very similar UV−vis and 1H NMR spectra, consistent with the formation of monomeric stannylene units. Cooling a solution of 1 resulted in a color change to pink and the appearance of a new UV−vis absorption at 506 nm, consistent with the formation of a symmetric dimeric structure at low temperature. The different structures of 1 and 2 in the solid state are probably a result of packing effects. In contrast, the analogous reactions of (Ar′GeCl)2 with LiC≡CR (R = SiMe3 or tBu) resulted in the exclusive formation of digermene derivatives Ar′(RC≡C)GeGe(C≡CR)Ar′ (R = SiMe3 (3), tBu (4)), which maintain their dimeric structures in solution.
Co-reporter:Chengbao Ni, Hao Lei and Philip P. Power
Organometallics 2010 Volume 29(Issue 8) pp:1988-1991
Publication Date(Web):March 23, 2010
DOI:10.1021/om1000502
The reaction of the two-coordinate diaryls MAr′2 (M = Mn or Fe; Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) with excess NH3 below room temperature afforded the parent amido complexes {Ar′Mn(μ-NH2)(NH3)}2 (1) and {Ar′Fe(μ-NH2)}2 (2) in good yields. The reactions were accompanied by elimination of the arene Ar′H. Both complexes were obtained as dimers in which the metals are bridged by two NH2 ligands. The complex 1 also includes an ammonia (NH3) ligand bound to each manganese. Ammonia complexation did not occur in 2, and the metals remained three-coordinate. The metal electron configurations are high-spin and antiferromagnetically coupled.
Co-reporter:Chengbao Ni, James C. Fettinger and Philip P. Power
Organometallics 2010 Volume 29(Issue 1) pp:269-272
Publication Date(Web):December 10, 2009
DOI:10.1021/om9007136
Reactions of the Mn(I) inverted sandwich complex (η6-C7H8){MnAr*-3,5-iPr2}2 (Ar*-3,5-iPr2 = C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2) with bulky terphenyl azides afforded the dimeric Mn(II) amido/aryl complex {CH2C6H2-2-(C6H3-2-(N(H)MnAr*-3,5-iPr2)-3-(C6H2-2,4,6-Me3))-3,5-Me2}2 (1) and the binuclear Mn(II) complex (μ,η1:η1-NH-C6H3-2-(C6H2-3,5-tBu2)-6-(C6H3-3,5-tBu2)){MnAr*-3,5-iPr2}2 (2). Complex 1 arises via methyl hydrogen abstraction by the nitrogen atom and dimerization via radical coupling with C−C bond formation. Complex 2 was formed by phenyl hydrogen abstraction by the imido nitrogen atom, followed by incorporation of a further MnAr*-3,5-iPr2 unit. In addition, complex 2 features two different manganese environments and is also the first structurally characterized heteroleptic two-coordinate diaryl Mn(II) species.
Co-reporter:Oracio Serrano;Elke Hoppe
Journal of Cluster Science 2010 Volume 21( Issue 3) pp:449-460
Publication Date(Web):2010 September
DOI:10.1007/s10876-010-0325-7
Reaction of Ni(CO)4 in toluene at room temperature with one equivalent of GaAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) and GaL (L = HC[C(Me)N(C6H3-2,6-iPr2)]2) formed the mono-substituted Ni(CO)3(GaAr′) (1) and Ni(CO)3(GaL) (3), respectively. Compound 1 decomposed under reduced pressure or upon heating in toluene to give the new cluster species Ni4(CO)7(GaAr′)3 (2). Reaction of 3 with a second equivalent of GaL in toluene at 95 °C afforded the disubstituted complex Ni(CO)2(GaL)2 (4). All the compounds were characterized by IR, 1H and 13C{1H} NMR spectroscopy and X-ray crystallographic studies were undertaken to elucidate the structures of the complexes 2, 3 and 4.
Co-reporter:Xinping Wang Dr.;Yang Peng;Zhongliang Zhu;JamesC. Fettinger Dr.;PhilipP. Power ;Jingdong Guo Dr.;Shigeru Nagase
Angewandte Chemie 2010 Volume 122( Issue 27) pp:4697-4701
Publication Date(Web):
DOI:10.1002/ange.201001086
Co-reporter:W. Alexander Merrill ; Troy A. Stich ; Marcin Brynda ; Gregory J. Yeagle ; James C. Fettinger ; Raymond De Hont ; William M. Reiff ; Charles E. Schulz ; R. David Britt
Journal of the American Chemical Society 2009 Volume 131(Issue 35) pp:12693-12702
Publication Date(Web):August 11, 2009
DOI:10.1021/ja903439t
The monomeric iron(II) amido derivatives Fe{N(H)Ar*}2 (1), Ar* = C6H3-2,6-(C6H2-2,4,6-Pri3)2, and Fe{N(H)Ar#}2 (2), Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2, were synthesized and studied in order to determine the effects of geometric changes on their unusual magnetic properties. The compounds, which are the first stable homoleptic primary amides of iron(II), were obtained by the transamination of Fe{N(SiMe3)2}2, with HN(SiMe3)2 elimination, by the primary amines H2NAr* or H2NAr#. X-ray crystallography showed that they have either strictly linear (1) or bent (2, N−Fe−N = 140.9(2)°) iron coordination. Variable temperature magnetization and applied magnetic field Mössbauer spectroscopy studies revealed a very large dependence of the magnetic properties on the metal coordination geometry. At ambient temperature, the linear 1 displayed an effective magnetic moment in the range 7.0−7.50 μB, consistent with essentially free ion magnetism. There is a very high internal orbital field component, HL ≈ 170 T which is only exceeded by a HL ≈ 203 T of Fe{C(SiMe3)3}2. In contrast, the strongly bent 2 displayed a significantly lower μeff value in the range 5.25−5.80 μB at ambient temperature and a much lower orbital field HL value of 116 T. The data for the two amido complexes demonstrate a very large quenching of the orbital magnetic moment upon bending the linear geometry. In addition, a strong correlation of HL with overall formal symmetry is confirmed. ESR spectroscopy supports the existence of large orbital magnetic moments in 1 and 2, and DFT calculations provide good agreement with the physical data.
Co-reporter:Xinping Wang ; Yang Peng ; Marilyn M. Olmstead ; James C. Fettinger
Journal of the American Chemical Society 2009 Volume 131(Issue 40) pp:14164-14165
Publication Date(Web):September 16, 2009
DOI:10.1021/ja906053y
Reaction of the digermyne Ar′GeGeAr′ (1) with ONC6H4-2-CH3 affords a unique example of an unsymmetric singlet diradicaloid, the oxo/imido-bridged species Ar′Ge(μ-O)(μ-NC6H4-2-CH3)GeAr′ (2), which was characterized by spectroscopy, X-ray crystallography, and density functional theory computations. The direct reaction of 1 with O2 to generate the symmetric diradicaloid Ar′Ge(μ2-O)2GeAr′ led to the double-addition product Ar′Ge(μ2-O)2(η1,η1:μ2-O2)GeAr′ (8), which was also characterized structurally and spectroscopically. Calculations on simple models showed that the HOMO−LUMO energy gap decreases as the imido bridges in MeGe(μ-NH)2GeMe are replaced by oxygens, which is consistent with the higher reactivity of Ar′Ge(μ2-O)2GeAr′ toward further O2 addition.
Co-reporter:Yang Peng ; Jing-Dong Guo ; Bobby D. Ellis ; Zhongliang Zhu ; James C. Fettinger ; Shigeru Nagase
Journal of the American Chemical Society 2009 Volume 131(Issue 44) pp:16272-16282
Publication Date(Web):October 16, 2009
DOI:10.1021/ja9068408
The reactions of hydrogen or ammonia with germylenes and stannylenes were investigated experimentally and theoretically. Treatment of the germylene GeAr#2 (Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2) with H2 or NH3 afforded the tetravalent products Ar#2GeH2 (1) or Ar#2Ge(H)NH2 (2) in high yield. The reaction of the more crowded GeAr′2 (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) with NH3 also afforded a tetravalent amide Ar′2Ge(H)NH2 (3), whereas with H2 the tetravalent hydride Ar′GeH3 (4) was obtained with Ar′H elimination. In contrast, the reactions with the divalent Sn(II) aryls did not lead to Sn(IV) products. Instead, arene eliminated Sn(II) species were obtained. SnAr#2 reacted with NH3 to give the Sn(II) amide {Ar#Sn(μ-NH2)}2 (5) and Ar#H elimination, whereas no reaction with H2 could be observed up to 70 °C. The more crowded SnAr′2 reacted readily with H2, D2, or NH3 to give {Ar′Sn(μ-H)}2 (6), {Ar′Sn(μ-D)}2 (7), or {Ar′Sn(μ-NH2)}2 (8) all with arene elimination. The compounds were characterized by 1H, 13C, and 119Sn NMR spectroscopy and by X-ray crystallography. DFT calculations revealed that the reactions of H2 with EAr2 (E = Ge or Sn; Ar = Ar# or Ar′) initially proceed via interaction of the σ orbital of H2 with the 4p(Ge) or 5p(Sn) orbital, with back-donation from the Ge or Sn lone pair to the H2 σ* orbital. The subsequent reaction proceeds by either an oxidative addition or a concerted pathway. The experimental and computational results showed that bond strength differences between germanium and tin, as well as greater nonbonded electron pair stabilization for tin, are more important than steric factors in determining the product obtained. In the reactions of NH3 with EAr2 (E = Ge or Sn; Ar = Ar# or Ar′), the divalent ArENH2 products were calculated to be the most stable for both Ge and Sn. However the tetravalent amido species Ar2Ge(H)NH2 were obtained for kinetic reasons. The reactions with NH3 proceed by a different pathway from the hydrogenation process and involve two ammonia molecules in which the lone pair of one NH3 becomes associated with the empty 4p(Ge) or 5p(Sn) orbital while a second NH3 solvates the complexed NH3 via intermolecular N−H···N interactions.
Co-reporter:Chengbao Ni and Philip P. Power
Chemical Communications 2009 (Issue 37) pp:5543-5545
Publication Date(Web):17 Aug 2009
DOI:10.1039/B912312A
The iron(II) diaryl FeAr′2 (1) (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) reacts cleanly with O2 or CO to afford the monomeric, two-coordinate bis(aryloxide) Fe(OAr′)2 (2) or the η2-acyl–carbonyl complex (η2-Ar′CO)2Fe(CO)2 (3) viaoxygen or CO insertion into the Fe–C bonds; complex 2 has a strictly linear geometry and shows remarkable resistance to O2oxidation.
Co-reporter:Chengbao Ni, Bobby D. Ellis, Gary J. Long and Philip P. Power
Chemical Communications 2009 (Issue 17) pp:2332-2334
Publication Date(Web):25 Mar 2009
DOI:10.1039/B901494B
Reaction of Ar′CrCrAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2) with heterocumulene reagents N2O or N3(1-Ad) resulted in Ar′Cr(μ-O)2Cr(O)Ar′ or Ar′Cr(μ2:η1,η3-N3(1-Ad))CrAr′ which have no metal–metal bonding.
Co-reporter:Chengbao Ni, Gary J. Long, Fernande Grandjean and Philip P. Power
Inorganic Chemistry 2009 Volume 48(Issue 24) pp:11594-11600
Publication Date(Web):November 13, 2009
DOI:10.1021/ic901462t
The synthesis and characterization of a series of first-row aryl transition metal derivatives of the simplest dialkylamido ligand NMe2 are reported. The complexes Cr{Ar′Cr(μ-NMe2)2}2 (1) and {Ar′M(μ-NMe2)}2 (M = Mn (2), Fe (3); Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) were obtained by reaction of the aryl metal halides {Ar′M(μ-X)}2 (M = Cr, X = Cl; M = Fe, X = Br) or {Li(THF)Ar′MnI2}2 with LiNMe2 in a 1:2 ratio. A similar reaction of {Ar#Co(μ-I)}2 (Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2) and LiNMe2 in hexanes gave the unusual complex {Ar#Co(μ-I)(η1-CH2═NCH3)}2 (4), in which the NMe2 ligand is dehydrogenated to afford a complexed imine. Complexes 1−4 were characterized by X-ray crystallography, UV−vis spectroscopy, and magnetic measurements. In the unique trinuclear complex 1, the central chromium(II) ion is bound to four NMe2 groups in a square planar fashion. The NMe2 groups also bridge to the two outer chromium(II) ions, which are bound to a terminal Ar′ group to yield a rare example of three-coordinate T-shaped geometry at these atoms. In the dimers 2 and 3, each metal center is coordinated to a terminal terphenyl ligand and two bridging NMe2 groups to give a distorted trigonal planar geometry. In contrast, the reaction of LiNMe2 with {Ar#Co(μ-I)}2 in a 2:1 ratio did not yield an amido product; instead, the NMe2 ligand underwent hydrogen elimination. As a result, in the dimeric structure of 4, each cobalt ion is coordinated to a terphenyl ligand, two bridging iodides, and a neutral methylimine ligand, CH2═NCH3, to yield a very distorted tetrahedral cobalt(II) coordination environment. The magnetic properties of 1−4 revealed antiferromagnetic exchange coupling between the metal ions with J = −47(1) cm−1 and J13 = −25(1) cm−1 for 1, J = −38(1) cm−1 for 2, J = −75(3) cm−1 for 3, and J = −32(4) cm−1 for 4; the latter compound exhibited an unusually large temperature independent contribution to its molar magnetic susceptibility.
Spin-State Crossover with Structural Changes in a Cobalt(II) Organometallic Species: Low-Coordinate, First Row, Heteroleptic Amido Transition Metal Aryls. Synthesis and Characterization of Ar′MN(H)Ar# (M = Mn, Fe, Co) (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2, Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2)
Co-reporter:Chengbao Ni, James C. Fettinger, Gary J. Long and Philip P. Power
Inorganic Chemistry 2009 Volume 48(Issue 6) pp:2443-2448
Publication Date(Web):February 12, 2009
DOI:10.1021/ic801660a
The synthesis and characterization of the monomeric aryl transition metal amido complexes Ar′MN(H)Ar# (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2, Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2, M = Mn (1), Fe (2), Co(3a, b)) are reported. The compounds were characterized by X-ray crystallography, electronic and infrared spectroscopy, and magnetic measurements. At about 90 K the complexes 1 and 2 possess quasi-two coordinate geometry with a weak, secondary, M---C interaction involving a flanking aryl ring from an amido group. In contrast, at the same temperature, their cobalt analogue 3a features a strong Co-η6-flanking ring interaction to give an effectively higher coordination geometry. Magnetic studies of 1−3a showed that 1 and 2 have high spin configurations, whereas the cobalt species 3a has a low-spin configuration (S = 1/2). However, 3a undergoes a spin crossover to a high spin (S = 3/2) state 3b near 229 K. An X-ray structural determination above the crossover temperature at 240 K showed that the low temperature structure of 3a had changed to 3b which involves a weak secondary M---C interaction analogous to those in 1 and 2. The complexes 1−3 are very rare examples of heteroleptic quasi-two coordinate open shell transition metal complexes.
Co-reporter:Xinping Wang, Chengbao Ni, Zhongliang Zhu, James C. Fettinger and Philip P. Power
Inorganic Chemistry 2009 Volume 48(Issue 6) pp:2464-2470
Publication Date(Web):February 17, 2009
DOI:10.1021/ic801713v
Reactions of the digermyne Ar′GeGeAr′ (Ar′ = C6H3-2,6(C6H3-2,6-Pri2)2) (1) with four different azides R′N3 (R = Me3Sn, nBu3Sn, PhSCH2, or 1-adamantanyl) are described. Treatment of 1 with Me3SnN3 or nBu3SnN3 afforded the low-valent germanium (II) parent amido derivative, Ar′Ge(μ2-NH2)2GeAr′ (3) or the high-valent germanium (IV) parent imido derivative, Ar′(nBu3Sn)Ge(μ2-NH)2Ge(SnnBu3)Ar′ (4), respectively. Addition of AdN3 (Ad =1-admantanyl) yielded a monoimide bridged species Ar′Ge(μ2-NAd)GeAr′ (5). The structure of 5 differs from that of the diradicaloid Ar′Ge(μ2-NSiMe3)2GeAr′ (2), which was previously obtained from the analogous reaction of 1 with Me3SiN3. The reaction of 1 with PhSCH2N3 afforded the germanium ketimide Ar′Ge(SPh)2(N=CH2) (6) containing the imino −N=CH2 functional group. These reactions demonstrate a remarkable product dependence on the azide substituent. All compounds were spectroscopically and structurally characterized. Both 3 and 4 feature a four-membered Ge2N2 core. The structure of 5 is stabilized by CH-π interactions while 6 features a rare example of a π-π interaction between an aromatic ring and a non-aromatic double bond (N=C). The mechanism of formation of 3−6 are discussed. It is proposed that 3 and 4 are obtained via diradical imido intermediates followed by H-abstraction from solvents, whereas 6 was formed by the activation of azide group in concert with C−S bond cleavage.
Co-reporter:Chengbao Ni, Bobby D. Ellis, Troy A. Stich, James C. Fettinger, Gary J. Long, R. David Britt and Philip P. Power
Dalton Transactions 2009 (Issue 27) pp:5401-5405
Publication Date(Web):26 May 2009
DOI:10.1039/B904647J
The reduction of {ArFeBr}2 (Ar = terphenyl) with KC8 in the presence of excess PMe3 afforded the Fe(I) complex 3,5-Pri2-Ar′Fe(PMe3) (1) (Ar′-3,5-Pri2 = C6H-2,6-(C6H3-2,6-Pri2)-3,5-Pri2), which has a structure very different from the previously reported, linear Cr(I) species 3,5-Pri2-Ar*Cr(PMe3) (3,5-Pri2-Ar* = C6H-2,6-(C6H2–2,4,6-Pri3)2–3,5-Pri2) and features a strong Fe-η6-aryl interaction with the flanking aryl ring of the terphenyl ligand. In sharp contrast, the reduction of {ArCoCl}2 (Ar = 3,5-Pri2-Ar′ and Ar′) afforded the allyl complexes Co(η3-{1-(H2C)2C-C6H3–2-(C6H2–2,4-Pri2–5-(C6H3–2,6-Pri2))-3-Pri})(PMe3)3 (4) and Co(η3-{1-(H2C)2C-C6H3–2-(C6H4–3-(C6H3–2,6-Pri2))-3-Pri})(PMe3)3 (5) formed by an unusual triple dehydrogenation of an isopropyl group. It is proposed that the reduction initially generates an intermediate 3,5-Pri2-Ar′Co(PMe3), which is similar in structure to 1, followed by 3,5-Pri2-Ar′Co(PMe3) decomposition to a cobalt hydride intermediate and dehydrogenation of the isopropyl groupvia remote C–H activation induced by PMe3 complexation. Complexes 1, 4, and 5 were characterized by X-ray crystallography. In addition, 1 was studied by NMR and EPR spectroscopy; 4 and 5 were characterized by NMR spectroscopy.
Co-reporter:Chengbao Ni, Brian Rekken, James C. Fettinger, Gary J. Long and Philip P. Power
Dalton Transactions 2009 (Issue 39) pp:8349-8355
Publication Date(Web):21 Aug 2009
DOI:10.1039/B911978G
The synthesis and characterization of the mononuclear manganese primary amido complex Mn{N(H)Ar#}2 (1), its Lewis base adducts Mn{N(H)Ar#}2(L) (Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2; L = THF (2), and C5H5N (3)), and Mn{N(H)Ar*}2 (4) (Ar* = C6H3-2,6-(C6H2-2,4,6-iPr3)2) are described. Complex 1 was prepared by the reaction of MnCl2 with two equivalents of LiN(H)Ar# in benzene. X-Ray crystallography showed that it had a quasi-two-coordinate strongly bent geometry with Mn–N = 1.979(3) Å, N–Mn–N = 138.19(9)° and secondary Mn⋯C(aryl ring) interactions. In contrast, complex 4, which was prepared by the same route as 1, has an almost linear geometry with a wide N–Mn–N angle of 176.1(2)°. The complexes 1 and 4 are the first structurally characterized homoleptic primary amido derivatives of manganese. Complex 1 did not react with THF or pyridine, but its THF complex 2 could be formed by the reaction of MnI2(THF)2 with two equivalents of LiN(H)Ar#. Similarly, complex 3 was prepared either by the direct reaction of MnCl2 with LiN(H)Ar# in hexanes in the presence of pyridine, or by reaction of the THF complex 2 with excess pyridine. Attempts to form Lewis base complexes of 4 by similar routes led to the recovery of unreacted 4. The results suggested that reaction with Lewis bases is prevented by secondary interactions (1) or steric effects (4). Magnetic studies show that the manganese(II) ions in 1–4 have high spin configurations with S = and small zero-field splittings, D, of ca.±1.5 to ±3 cm−1.
Co-reporter:Zhongliang Zhu;Xinping Wang Dr.;MarilynM. Olmstead ;PhilipP. Power
Angewandte Chemie 2009 Volume 121( Issue 11) pp:2061-2064
Publication Date(Web):
DOI:10.1002/ange.200805718
Co-reporter:Zhongliang Zhu;Xinping Wang Dr.;Yang Peng;Hao Lei;JamesC. Fettinger Dr.;Eric Rivard Dr. ;PhilipP. Power
Angewandte Chemie 2009 Volume 121( Issue 11) pp:2065-2068
Publication Date(Web):
DOI:10.1002/ange.200805982
Co-reporter:Zhongliang Zhu;Xinping Wang Dr.;MarilynM. Olmstead ;PhilipP. Power
Angewandte Chemie International Edition 2009 Volume 48( Issue 11) pp:2027-2030
Publication Date(Web):
DOI:10.1002/anie.200805718
Co-reporter:Zhongliang Zhu;Xinping Wang Dr.;Yang Peng;Hao Lei;JamesC. Fettinger Dr.;Eric Rivard Dr. ;PhilipP. Power
Angewandte Chemie International Edition 2009 Volume 48( Issue 11) pp:2031-2034
Publication Date(Web):
DOI:10.1002/anie.200805982
Co-reporter:Chengbao Ni and Philip P. Power
Organometallics 2009 Volume 28(Issue 22) pp:6541-6545
Publication Date(Web):October 29, 2009
DOI:10.1021/om900724p
The synthesis and characterization of a series of divalent terphenyl transition metal methyl complexes {ArM(μ-Me)}2 (M = Cr (1), Ar = C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2, abbreviated as 3,5-iPr2-Ar*; M = Mn (2), Fe (3), Ar = C6H3-2,6-(C6H2-2,4,6-iPr3)2, abbreviated as Ar*) as well as a phenyl-bridged iron complex {Ar*Fe(μ-Ph)}2 (4) are described. Complexes 1−4 were prepared by reaction of the corresponding terphenyl metal halide with LiMe or LiPh and have dimeric structures, in which three-coordinate metals are bridged by methyl or phenyl groups. Each chromium atom in 1 features a further interaction with the ipso-carbon of the flanking aryl ring; while the manganese and iron atoms in 2 and 3 have distorted trigonal-planar geometry. Complexes 1−4 are rare examples of low-coordinate transition metal complexes of methyl or phenyl groups, and they were characterized by X-ray crystallography, NMR, and UV−vis spectroscopy, elemental analysis, and magnetic measurements.
Co-reporter:Chengbao Ni, Gary J. Long and Philip P. Power
Organometallics 2009 Volume 28(Issue 17) pp:5012-5016
Publication Date(Web):August 12, 2009
DOI:10.1021/om900542j
The reaction of {Ar′Fe(μ-Br)}2 (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) with LiC≡CPh afforded the unusual 1,3-butadiene-1,4-diyl Fe(I)-coupled derivative Fe2{Ar′C═C(Ph)-C(Ph)═CAr′} (1), whereas the reaction of {Ar′Fe(μ-Br)}2 with LiC≡CtBu yielded the monomeric Fe(II) “ate” complex Ar′Fe(C≡CtBu)2{Li(THF)2} (2). Complexes 1 and 2 were characterized by X-ray crystallography, NMR, and UV−vis spectroscopy and magnetic measurements. In 1 the dimeric structure is a result of Ar′ group transfer to the iron-bound carbon of the acetylide ligand and subsequent dimerization via coupling of the phenyl-substituted carbons. The irons are antiferromagnetically coupled, and the iron−iron separation is 2.5559(3) Ǻ. In 2 the high-spin iron atom has distorted trigonal-planar coordination with a THF-complexed lithium ion associated with the Ar′Fe(C≡CtBu)2 anion via interactions with the tBu-substituted alkyne carbons.
Co-reporter:Zhongliang Zhu, Robert J. Wright, Zachary D. Brown, Alexander R. Fox, Andrew D. Phillips, Anne F. Richards, Marilyn M. Olmstead and Philip P. Power
Organometallics 2009 Volume 28(Issue 8) pp:2512-2519
Publication Date(Web):March 31, 2009
DOI:10.1021/om900031v
Dimeric arylgallium/indium chalcogenides 7−10 of formula [Ar′ME]2 (Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2; M = Ga or In, E = O or S) were synthesized by the treatment of Ar′MMAr′ with N2O or elemental sulfur and characterized by NMR spectroscopy and X-ray crystallography. Their structures feature three-coordinate, +3 oxidation state metal centers with planar M2E2 cores. The cores were almost perfectly square for E = O, but for E = S, they were distorted parallelograms in 7−10. The M–E bond lengths were shorter than those in the higher aggregated species [RME]n (n ≥ 4) but comparable to those in M3+ aryloxides or thiolates featuring three-coordinate metals. Short M···M separations [2.553(1) Å in 7, 2.8882(4) Å in 8, 2.8276 Å (avg.) in 9, and 3.1577(8) Å in 10] are observed. Low oxidation heavier group 13/group 16 chalcogenolate isomers 16−19 of formula [Ar′EM]2 (M = In or Tl, E = O or S) were also synthesized and characterized. In the +1 compounds [Ar′EIn]2 (O, 16; S, 19) together, with the In +3 species [Ar′InE]2 (O, 8; S, 10), represent the first structurally characterized isomeric pairs of organo group 13 metal/chalcogen derivatives. The E−M bonds in 16−19 were 2.3329 (avg.), 2.560 (avg.), 2.8189 (avg.), and 2.897 Å (avg.), respectively, which are 0.3−0.4 Å longer than the corresponding In−chalcogen distances in 8 and 10 as a result of the lower oxidation state, the large In+ ionic size, and the reduced ionic contribution to the bond strength in 16 and 19. The compounds 16−19 also displayed M−arene interactions to the flanking aryl rings of the Ar′ ligands. The Tl−arene contacts in the crystal structure of 17 are preserved in solution, as evidenced by 13C−Tl coupling. Attempts to thermally interconvert the isomeric pairs 8, 10 and 16, 18 led to decomposition of the complexes.
Co-reporter:Zhongliang Zhu, James C. Fettinger, Marilyn M. Olmstead and Philip P. Power
Organometallics 2009 Volume 28(Issue 7) pp:2091-2095
Publication Date(Web):March 19, 2009
DOI:10.1021/om900005t
The synthesis and characterization of arylzinc hydrides Ar*Zn(μ-H)2ZnAr* (Ar* = C6H3-2,6-(C6H2-2,4,6-Pri3)2, 5) and {(4-Me3Si-Ar*)Zn(μ-H)2Zn(Ar*-4-SiMe3)} (4-Me3Si-Ar* = C6H2-2,6-(C6H2-2,4,6-Pri3)2-4-SiMe3, 7) as well as the monomeric arylcadmium hydride Ar*CdH (9) are described. They were prepared by the transmetalation of the corresponding aryl metal iodides with NaH. The Ar*CdH monomer displayed significantly greater thermal stability than its recently reported dimeric congener Ar′Cd(μ-H)2CdAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2), which decomposed at room temperature to afford Ar′CdCdAr′. This result supports the proposal that decomposition of the metal hydrides occurs by an associative mechanism. The reactions of these compounds with TEMPO (2,2,6,6-tetramethylpiperidinyl oxide) were also examined, but the only crystalline product obtained was 4-Me3Si-Ar*ZnTEMPO, in which the metal is bound to the TEMPO ligand in a quasi side-on fashion primarily through the oxygen but with a significant zinc−nitrogen interaction.
Co-reporter:Bobby D. Ellis;James C. Fettinger;Xinping Wang;Yang Peng
Science 2009 Volume 325(Issue 5948) pp:1668-1670
Publication Date(Web):25 Sep 2009
DOI:10.1126/science.1176443
Tin Two-Step
Doubly and triply bonded carbon compounds have a well-studied tendency to link up with one another and form rings. The rates of these reactions and their relative susceptibilities to acceleration by heat versus light are encapsulated in the decades-old Woodward-Hoffmann rules. More recently, alkene and alkyne analogs have been prepared with heavier elements such as silicon and tin substituted for carbon. Peng et al. (p. 1668; see the Perspective by Sita) have now discovered that two distannynes (compounds with triply bonded tins) react readily with ethylene to form cycloadducts, with tin-carbon σ bonds taking the place of C-C and Sn-Sn π bonds. These products, characterized spectroscopically and crystallographically, are only loosely bound at room temperature, easily reverting to their multiply bonded precursors on gentle heating.
Co-reporter:Zhongliang Zhu Dr.;RolC. Fischer Dr.;BobbyD. Ellis Dr.;Eric Rivard Dr.;W.Alexer Merrill;MarilynM. Olmstead ;PhilipP. Power ;J.D. Guo Dr.;Shigeru Nagase ;Lihung Pu
Chemistry - A European Journal 2009 Volume 15( Issue 21) pp:5263-5272
Publication Date(Web):
DOI:10.1002/chem.200900201
Co-reporter:Yang Peng, Marcin Brynda, Bobby D. Ellis, James C. Fettinger, Eric Rivard and Philip P. Power
Chemical Communications 2008 (Issue 45) pp:6042-6044
Publication Date(Web):17 Oct 2008
DOI:10.1039/B813442A
Dihydrogen reacts directly with a range of distannynes at ca. 25 °C under one atmosphere pressure to afford symmetric hydrogen bridged or unsymmetric stannylstannane products in high yield.
Co-reporter:Chengbao Ni, James C. Fettinger, Gary J. Long, Marcin Brynda and Philip P. Power
Chemical Communications 2008 (Issue 45) pp:6045-6047
Publication Date(Web):21 Oct 2008
DOI:10.1039/B810941A
Reaction of 3,5-Pri2Ar*Fe(η6-C6H6)(3,5-Pri2Ar* = C6H1-2,6-(C6H2-2,4,6-Pri3)2-3,5-Pri2) with N3C6H3-2,6-Mes2 (Mes = C6H2-2,4,6-Me3) afforded the dimeric iron(II) amido/aryl complex {CH2C6H2-2(C6H3-2-N(H)FeAr*-3,5-Pri2)-3,5-Me2}2 (1) which arises viamethyl hydrogen abstraction by nitrogen and dimerization of the radical via C–C bond formation; in contrast, reaction of 3,5-Pri2Ar*Fe(η6-C6H6) with N3(1-Ad) (1-Ad = 1-adamantanyl) gave the iron(V) bis(imido) complex 3,5-Pri2Ar*Fe{N(1-Ad)}2 (2).
Co-reporter:Hao Lei ; Bobby D. Ellis ; Chengbao Ni ; Fernande Grandjean ; Gary J. Long
Inorganic Chemistry 2008 Volume 47(Issue 22) pp:10205-10207
Publication Date(Web):October 15, 2008
DOI:10.1021/ic8015782
The half-sandwich cobalt(I) complex (η6-C7H8)CoAr*-3,5-iPr2 (Ar*-3,5-iPr2 = −C6H-2,6-(C6H2-2,4,6-iPr3)2-3,5-iPr2) was synthesized by reduction of [3,5-iPr2Ar*Co(μ-Cl)]2 in toluene. It reacts with CO or NO to afford the unusual complexes [3,5-iPr2Ar*C(O)Co(CO)] or [3,5-iPr2Ar*N(NO)OCo(NO)2].
Co-reporter:Eric Rivard and Philip P. Power
Dalton Transactions 2008 (Issue 33) pp:4336-4343
Publication Date(Web):24 Jul 2008
DOI:10.1039/B801400K
This Perspective discusses the synthesis and reactivity of low valent Group 14 hydrides of germanium and tin. The use of hindered terphenyl ligands has facilitated the isolation of a number of unusual new main group hydride structural types (each predicted by computational work), and has culminated in the use of these species as precursors to new cluster archetypes.
Co-reporter:Robert Wolf;Jelena Fischer;Rol C. Fischer;James C. Fettinger
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 16) pp:
Publication Date(Web):
DOI:10.1002/ejic.200890041
Abstract
The cover picture shows a bismuth crystal that has a similar shape to the molecular structure of the (dibismuthene)iron complex [Fe(CO)4(Bi2Ar′2)] [Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)], the first compound with a three-membered Bi2Fe ring. The new complex was obtained from the 1:1 reaction of Na2[Fe(CO)4] and Ar′BiCl2. In a similar vein, the double-bonded dibismuthene Ar′2Bi2 and the single-bonded dibismuthane Ar′2Bi2Cl2 were isolated from attempted metathesis reactions of Ar′BiCl2 with K2Si2(SiMe3)4 and KSi(SiMe3)3, respectively. Details are presented in the article by P. P. Power et al. on p. 2515 ff. We thank the Alexander von Humboldt Foundation, the Austrian Fonds zur Förderung der wissenschaftlichen Forschung, and the Max Kade Foundation for financial support of this work; Dr. J. Chris Slootweg is acknowledged for providing the picture of the bismuth crystal.
Co-reporter:Robert Wolf;Jelena Fischer;Rol C. Fischer;James C. Fettinger
European Journal of Inorganic Chemistry 2008 Volume 2008( Issue 16) pp:2515-2521
Publication Date(Web):
DOI:10.1002/ejic.200701334
Abstract
The reactions of terphenylbismuth dihalides with various reducing agents were investigated. Attempted metathesis of Ar′BiCl2 [Ar′ = 2,6-(2,6-iPr2-C6H3)2-C6H3] with one equivalent of KSi(SiMe3)3 gave the 1,2-dichlorodibismuthane Ar′(Cl)Bi–Bi(Cl)Ar′ (1) in 40 % yield. The reaction of Ar′BiCl2 (1) with the dianionic salt K2Si2(SiMe3)4 yielded the dibismuthene Ar′Bi=BiAr′ (2) in 72 %. The terphenylbismuth dihalides ArBiCl2 [Ar = 2,6-(2,6-iPr2-C6H3)2-C6H3 (Ar′), 2,6-(2,4,6-Me3-C6H2)2-C6H3 (Ar#)] were treated with Na2[Fe(CO)4] in THF to afford the iron dibismuthene complexes [Fe(CO)4(Bi2Ar′2)] (3) and [Fe(CO)4(Bi2Ar#2)] (4) in modest yields (25 and 15 % respectively). The compounds 1–4 were characterized by X-ray crystallography and by spectroscopic methods (1H and 13C NMR, IR, and UV/Vis spectroscopy). The results show that reduction of the bismuth center is strongly preferred over salt metathesis chemistry due to the reducing power of the silanide and ferrate salts and the strength of the Bi=Bi bond. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Co-reporter:Tailuan Nguyen;W.Alexer Merrill;Chengbao Ni;Hao Lei;JamesC. Fettinger Dr.;BobbyD. Ellis Dr.;GaryJ. Long ;Marcin Brynda Dr.;PhilipP. Power
Angewandte Chemie 2008 Volume 120( Issue 47) pp:9255-9257
Publication Date(Web):
DOI:10.1002/ange.200802657
Co-reporter:Tailuan Nguyen;W.Alexer Merrill;Chengbao Ni;Hao Lei;JamesC. Fettinger Dr.;BobbyD. Ellis Dr.;GaryJ. Long ;Marcin Brynda Dr.;PhilipP. Power
Angewandte Chemie International Edition 2008 Volume 47( Issue 47) pp:9115-9117
Publication Date(Web):
DOI:10.1002/anie.200802657
Co-reporter:Geoffrey H. Spikes and Philip P. Power
Chemical Communications 2007 (Issue 1) pp:85-87
Publication Date(Web):19 Oct 2006
DOI:10.1039/B612202G
The reaction of the “digermyne” Ar′GeGeAr′ (Ar′ = C6H3–2,6(C6H3–2,6-Pri2)2; Ge–Ge = 2.2850(6) Å) with mesityl isocyanide affords the bis adduct [Ar′GeGeAr′(CNMes)2] which results in the conversion of a Ge–Ge multiple bond to a long Ge–Ge single bond (= 2.6626(8) Å).
Co-reporter:Alexandra L. Pickering, Christoph Mitterbauer, Nigel D. Browning, Susan M. Kauzlarich and Philip P. Power
Chemical Communications 2007 (Issue 6) pp:580-582
Publication Date(Web):11 Jan 2007
DOI:10.1039/B614363F
Capped boron nanoparticles have been synthesized at room temperature by a simple route that does not involve the use of flammable boranes.
Co-reporter:Eric Rivard, Jochen Steiner, James C. Fettinger, Jason R. Giuliani, Matthew P. Augustine and Philip P. Power
Chemical Communications 2007 (Issue 46) pp:4919-4921
Publication Date(Web):24 Sep 2007
DOI:10.1039/B709446A
Two complementary synthetic routes to a pentagonal bipyramidal Sn7 cluster, Sn7Aryl2 (Aryl = terphenyl ligand), are reported.
Co-reporter:Eric Rivard, Andrew D. Sutton, James C. Fettinger, Philip P. Power
Inorganica Chimica Acta 2007 Volume 360(Issue 4) pp:1278-1286
Publication Date(Web):1 March 2007
DOI:10.1016/j.ica.2005.12.028
The very sterically encumbered secondary chlorophosphines ArTrip2P(Ph)Cl(ArTrip2=C6H3-2,6(C6H2-2,4,6-Pri3)) and ArMes2P(Ph)Cl(ArMes2=C6H3-2,6(C6H2-2,4,6-Me3)) were prepared from the respective aryllithium precursors and PhPCl2. Subsequent reduction of the chlorophosphines with Li[AlH4] yielded the corresponding phosphines ArylP(Ph)H in high yield; these afforded the lithium salts ArylP(Ph)Li upon treatment with nBuLi, and the synthesis and structural characterization of the monomeric terphenyl phosphide {[ArMes2P(Ph)]Li(THF)2}{[ArMes2P(Ph)]Li(THF)2} are described. Reaction of two equivalents of the lithium phosphide with SnCl2 afforded a rare example of a monomeric Sn(II)-diphosphide, [ArMes2P(Ph)]2Sn[ArMes2P(Ph)]2Sn.A series of very sterically encumbered secondary phosphines ArylP(Ph)H were prepared featuring bulky terphenyl substitutents. These species are promising synthons for the preparation of low-coordinate main group phosphido complexes.
Co-reporter:Eric Rivard, W. Alexander Merrill, James C. Fettinger and Philip P. Power
Chemical Communications 2006 (Issue 36) pp:3800-3802
Publication Date(Web):17 Aug 2006
DOI:10.1039/B609748K
A new class of heavier group 15 compounds demonstrating multiple bonding with boron has been synthesized using a simple donor-stabilization protocol.
Co-reporter:Robert J. Wright, Jochen Steiner, Samar Beaini, Philip P. Power
Inorganica Chimica Acta 2006 Volume 359(Issue 6) pp:1939-1946
Publication Date(Web):10 April 2006
DOI:10.1016/j.ica.2005.10.015
Reaction of the terphenyl derivative BrMgArMes2(ArMes2=C6H3-2,6-Mes2) (synthesized in “one pot” directly from BrMgMes and 1-lithio-2,6-dichlorobenzene) with p -toluenesulfonyl azide afforded the azide N3ArMes2(ArMes2=C6H3-2,6-Mes2) (1) in 43% yield. Treatment of 1 with LiAlH4 gave the amine H2NArMes2H2NArMes2 (2) in high yield (88%). Reaction of 2 with 1.1 equivalents of n -BuLi afforded the lithium derivative Li(H)NArMes2Li(H)NArMes2 (3), which was quenched with excess SiMe3Cl to yield the silyl amine HN(SiMe3)ArMes2HN(SiMe3)ArMes2 (4). Reaction of 4 with n -BuLi gave LiN(SiMe3)ArMes2LiN(SiMe3)ArMes2 (5) in 65% yield. The related secondary terphenyl methyl amine HN(Me)ArMes2HN(Me)ArMes2 (6) was synthesized by reaction of 2 with five equivalents of methyl iodide in refluxing acetonitrile. In addition, the tertiary amine Me2NArMes2Me2NArMes2 (7) was formed. Reaction of 6 with n -BuLi in hexane solvent provided the lithium derivative [LiN(Me)ArMes2]2[LiN(Me)ArMes2]2 (8). All compounds were characterized by 1H and 13C NMR spectroscopy. Compounds 2, 4, and 6 were found to be monomeric and 8 dimeric in the solid state by X-ray crystallography. Compound 8 featured a dimeric Li2N2 core, where the Li ions are two coordinate.The sterically encumbering terphenyl silyl and alkyl amines HN(R)Mes2HN(R)Mes2 (R = Me and SiMe3) have been synthesized from the primary amine, H2NMes2H2NMes2. Reaction of these amines with n -BuLi afforded their lithium derivatives, LiN(R)ArMes2LiN(R)ArMes2.
Co-reporter:Zhongliang Zhu;Robert J. Wright Dr.;Marilyn M. Olmstead ;Eric Rivard Dr.;Marcin Brynda Dr.
Angewandte Chemie International Edition 2006 Volume 45(Issue 35) pp:
Publication Date(Web):14 AUG 2006
DOI:10.1002/anie.200601926
Unique interactions: Ar′ZnZnAr′ (1; Ar′=C6H3-2,6-(C6H3-2,6-iPr2)2), the dimer Ar′Zn(μ-H)2ZnAr′ (2), and the unprecedented species Ar′Zn(μ-H)(μ-Na)ZnAr′ (3) were synthesized and fully characterized. DFT calculations show that the ZnZn bonding interactions in 1 differ from those of other ZnZn compounds, and the calculations also indicate a new type of ZnZn bond in 3.
Co-reporter:Marcin Brynda Dr.;Rolfe Herber ;Peter B. Hitchcock Dr.;Michael F. Lappert ;Israel Nowik Dr. ;Andrey V. Protchenko Dr.;Aleš Růžička Dr.;Jochen Steiner Dr.
Angewandte Chemie International Edition 2006 Volume 45(Issue 26) pp:
Publication Date(Web):7 JUN 2006
DOI:10.1002/anie.200600292
A perfect tin! Two 15-nuclear tin metalloid clusters [Sn15Z6] (Z=N(2,6-iPr2C6H3)(SiMe2X); X=Me, Ph), having an unprecedented body-centered metal core (see picture; only N atoms of the amide ligands shown), were prepared by reduction of the appropriate amidotin(II) chloride with KC8 or Li[BHsBu3]. Mössbauer spectra showed two distinct quadrupole-splitting sites in the ratio of 1.5:1 for the Sn9 atoms and the six amido-bound tin atoms.
Co-reporter:Marcin Brynda Dr.;Rolfe Herber ;Peter B. Hitchcock Dr.;Michael F. Lappert ;Israel Nowik Dr. ;Andrey V. Protchenko Dr.;Aleš Růžička Dr.;Jochen Steiner Dr.
Angewandte Chemie International Edition 2006 Volume 45(Issue 26) pp:
Publication Date(Web):16 JUN 2006
DOI:10.1002/anie.200690089
Co-reporter:Robert J. Wright Dr.;Marcin Brynda Dr.
Angewandte Chemie International Edition 2006 Volume 45(Issue 36) pp:
Publication Date(Web):9 AUG 2006
DOI:10.1002/anie.200601925
An alkyne analogue with Al: The first “dialuminyne” of formula Na2[Ar′AlAlAr′] (see picture; Ar′=C6H3-2,6-(C6H3-2,6-iPr2)2) was synthesized and characterized by X-ray crystallography. The structure contains a planar trans-bent C–Al–Al–C array with an AlAl bond length of 2.428(1) Å and a bending angle of 131.71(7)° at Al.
Co-reporter:Marcin Brynda Dr.;Rolfe Herber ;Peter B. Hitchcock Dr.;Michael F. Lappert ;Israel Nowik Dr. ;Andrey V. Protchenko Dr.;Aleš Růžička Dr.;Jochen Steiner Dr.
Angewandte Chemie 2006 Volume 118(Issue 26) pp:
Publication Date(Web):7 JUN 2006
DOI:10.1002/ange.200600292
Jede Menge Zinn! Zwei Metalloidcluster mit jeweils 15 Zinnatomen, [Sn15Z6] (Z=N(2,6-iPr2C6H3)(SiMe2X); X=Me, Ph), und einem neuartigen innenzentrierten Metallkern (siehe Bild; nur die N-Atome der Amidliganden sind gezeigt) entstanden bei der Reduktion der Amidozinn(II)-chloride mit KC8 oder Li[BHsBu3]. Mößbauer-Spektroskopie ergab zwei Quadrupolaufspaltungen im Verhältnis 1.5:1 für die Sn9-Atome und die sechs amidgebundenen Zinnatome.
Co-reporter:Marcin Brynda Dr.;Rolfe Herber ;Peter B. Hitchcock Dr.;Michael F. Lappert ;Israel Nowik Dr. ;Andrey V. Protchenko Dr.;Aleš Růžička Dr.;Jochen Steiner Dr.
Angewandte Chemie 2006 Volume 118(Issue 26) pp:
Publication Date(Web):16 JUN 2006
DOI:10.1002/ange.200690089
Co-reporter:Zhongliang Zhu;Robert J. Wright Dr.;Marilyn M. Olmstead ;Eric Rivard Dr.;Marcin Brynda Dr.
Angewandte Chemie 2006 Volume 118(Issue 35) pp:
Publication Date(Web):14 AUG 2006
DOI:10.1002/ange.200601926
Einzigartige Wechselwirkung: Ar′ZnZnAr′ (1; Ar′=C6H3-2,6-(C6H3-2,6-iPr2)2), das Dimer Ar′Zn(μ-H)2ZnAr′ (2) und das neuartige Ar′Zn(μ-H)(μ-Na)ZnAr′ (3) wurden synthetisiert und vollständig charakterisiert. Nach DFT-Rechnungen unterscheiden sich die Zn-Zn-Wechselwirkungen in 1 von denen in anderen Zn-Zn-Verbindungen, außerdem weisen die Rechnungen auf einen neuen Typ von Zn-Zn-Bindung in 3 hin.
Co-reporter:Robert J. Wright Dr.;Marcin Brynda Dr.
Angewandte Chemie 2006 Volume 118(Issue 36) pp:
Publication Date(Web):9 AUG 2006
DOI:10.1002/ange.200601925
Ein Alkinanalogon mit Al: Das erste „Dialuminin“ mit der Formel Na2[Ar′AlAlAr′] (siehe Bild; Ar′=C6H3-2,6-(C6H3-2,6-iPr2)2) wurde synthetisiert und röntgenographisch charakterisiert. Die Struktur weist planare, trans-gebogene C-Al-Al-C-Ketten mit einer Al-Al-Bindungslänge von 2.428(1) Å und einem Biegewinkel an Al von 131.71(7)° auf.
Co-reporter:Tailuan Nguyen;Andrew D. Sutton;Marcin Brynda;James C. Fettinger;Gary J. Long
Science 2005 Vol 310(5749) pp:844-847
Publication Date(Web):04 Nov 2005
DOI:10.1126/science.1116789
Abstract
Although in principle transition metals can form bonds with six shared electron pairs, only quadruply bonded compounds can be isolated as stable species at room temperature. Here we show that the reduction of {Cr(μ-Cl)Ar′}2 [where Ar′ indicates C6H3-2,6(C6H3-2,6-Pri2)2 and Pr indicates isopropyl] with a slight excess of potassium graphite has produced a stable compound with fivefold chromium-chromium (Cr–Cr) bonding. The very air- and moisture-sensitive dark red crystals of Ar′CrCrAr′ were isolated with greater than 40% yield. X-ray diffraction revealed a Cr–Cr bond length of 1.8351(4) angstroms (where the number in parentheses indicates the standard deviation) and a planar transbent core geometry. These data, the structure's temperature-independent paramagnetism, and computational studies support the sharing of five electron pairs in five bonding molecular orbitals between two 3d5 chromium(I) ions.
Co-reporter:Geoffrey H. Spikes, Yang Peng, James C. Fettinger, Jochen Steiner and Philip P. Power
Chemical Communications 2005 (Issue 48) pp:6041-6043
Publication Date(Web):09 Nov 2005
DOI:10.1039/B513189H
The reactions of the digermanium and ditin alkyne analogues Ar′MMAr′ (M = Ge or Sn) with R2NO, (R2NO = Me2C(CH2)3CMe2NO or N2O), result in complete MM bond cleavage to afford the germylene :Ge(Ar′)ONR2 or the germanium(II) or tin(II) hydroxides {M(Ar′)(μ–OH)}2.
Co-reporter:Philip P. Power
Applied Organometallic Chemistry 2005 Volume 19(Issue 4) pp:
Publication Date(Web):8 MAR 2005
DOI:10.1002/aoc.824
Recently published work on the syntheses and reactivity of the germanium, tin, and lead analogues of alkynes is summarized. The heavier Group 14 ‘alkynes’ are stabilized by bulky terphenyl ligands and are thermally robust crystalline solids. However, they are extremely reactive and their reactivity decreases in the order Ge > Sn > Pb. Their spectroscopy and reactivity patterns suggest that the germanium species, in particular, has considerable diradical character. This hypothesis is also supported by preliminary density functional theory calculations. Copyright © 2005 John Wiley & Sons, Ltd.
Co-reporter:Shirley Hino, Marilyn M. Olmstead, James C. Fettinger, Philip P. Power
Journal of Organometallic Chemistry 2005 Volume 690(Issue 6) pp:1638-1644
Publication Date(Web):15 March 2005
DOI:10.1016/j.jorganchem.2005.01.011
The syntheses and characterization of two new terphenyl iodides 2,6-(2,3,4,5,6-Me5C6)2C6H3I (ArPmp2I)(ArPmp2I) and 2,6-(3,5-Bu2tC6H3)2C6H3I(ArDbp2I)(ArDbp2I) are described. Treatment of these with LiBun or LiBut afforded their lithium salts [ArPmp2Li]2[ArPmp2Li]2 (2), ArDbp2{Li(OEt2)}2IArDbp2{Li(OEt2)}2I (3), and [ArDbp2Li]2[ArDbp2Li]2 (4), which were spectroscopically characterized. The X-ray crystal structures of 2 and the “halide-rich” species 3 as well as that of the previously known [2,6-(2,6-Me2C6H3)2C6H3Li]2 (i.e. [ArXyl2Li]2[ArXyl2Li]2, 1) were determined. The structures of both 1 and 2 are dimers in which the lithiums bridge the ipso carbons of the central aryl ring of each terphenyl ligand and also interact with the ipso carbons of the flanking aryl rings. The structure of 3 is a rare example of a structurally characterized “halide rich” organolithium complex and has a monomeric arrangement in which two ether-coordinated lithiums are bridged by an ipso-carbon of the central aryl ring as well as an iodine atom.The syntheses and characterization of two new terphenyl ligands are described. The structures of their lithium salts, one of which is a rare example of a “halide rich” lithium aryl, and the structure of the previously known lithium terphenyl [LiC6H3-2,6-(C6H3-2,6-Me2)2]2, were determined.
Co-reporter:Anne F. Richards Dr.;Barrett E. Eichler Dr.;Marcin Brynda Dr.;Marilyn M. Olmstead
Angewandte Chemie 2005 Volume 117(Issue 17) pp:
Publication Date(Web):22 MAR 2005
DOI:10.1002/ange.200500117
Zinn kann seltene Beispiele organisch substituierter Cluster bilden, deren Strukturen denen von Zintl-Salzen ähneln. Die beiden neuen Arten metallreicher Organozinncluster, neutrales Sn9Ar3 (siehe Bild) und zwei ionische [Sn10Ar′3]+-Spezies, wurden strukturell charakterisiert, und ihre Bindungsverhältnisse wurden mit Dichtefunktionalrechnungen untersucht.
Co-reporter:Alexer R. Fox;Robert J. Wright;Eric Rivard Dr.
Angewandte Chemie 2005 Volume 117(Issue 47) pp:
Publication Date(Web):9 NOV 2005
DOI:10.1002/ange.200502865
Analog mit P: Die Reaktion des „Dithallens“ (TlAr)2 (1; Ar=C6H3-2,6-(C6H2-2,6-iPr2)2) mit P4 ergibt das thalliumkoordinierte Diaryltetraphosphabutadiendiid Tl2[P4(Ar)2] (2). Die negative Ladung im Anion von 2 ist über die P4-Gruppe delokalisiert, sodass eine mittlere P-P-Bindungsordnung von 1.33 resultiert.
Co-reporter:Anne F. Richards Dr.;Barrett E. Eichler Dr.;Marcin Brynda Dr.;Marilyn M. Olmstead
Angewandte Chemie International Edition 2005 Volume 44(Issue 17) pp:
Publication Date(Web):22 MAR 2005
DOI:10.1002/anie.200500117
Tin can form examples of rare organically substituted clusters whose structures are related to Zintl salts. The two new types of metal-rich organotin clusters, a neutral Sn9Ar3 (see picture) and two ionic [Sn10Ar′3]+ species, were structurally characterized and their bonding situation investigated by density functional calculations.
Co-reporter:Alexander R. Fox, Robert J. Wright, Eric Rivard,Philip P. Power
Angewandte Chemie International Edition 2005 44(47) pp:7729-7733
Publication Date(Web):
DOI:10.1002/anie.200502865
Co-reporter:Anne F. Richards, Marcin Brynda and Philip P. Power
Chemical Communications 2004 (Issue 14) pp:1592-1593
Publication Date(Web):07 Jun 2004
DOI:10.1039/B401507J
The first, well-characterized 1,2-dilithium salt of a group 14 element ethenide species, [{(dioxane)0.5(Et2O)LiGeC6H3-2,6-Mes2}2]∞, shows that the positions of the cations have a large effect on the length of the Ge–Ge double bond.
Co-reporter:Philip P. Power
Journal of Organometallic Chemistry 2004 Volume 689(Issue 24) pp:3904-3919
Publication Date(Web):29 November 2004
DOI:10.1016/j.jorganchem.2004.06.010
The development of bulky monodentate alkoxide, chalcogenolate (ER, E = S, Se or Te), amide, pnictide (ER2 = N, P, As), alkyl, aryl and silyl ligands is briefly surveyed. These ligands have played a key role in the advancement of the modern organometallic and inorganic chemistry of all the major blocks (s, p, d, and f) of the periodic table. Most importantly, they have permitted numerous new classes of compounds to be isolated and studied. The investigation of steric effects induced by these ligands has led to, inter alia, transition metal alkylidene and alkylidyne complexes, room temperature cleavage of dinitrogen, and a wide range of transition metal and lanthanide complexes with two or three coordination. In addition, their use has sparked a revolution in main group chemistry which has led to the isolation of stable species with bonds and/or oxidation states hitherto unknown in stable compounds.A brief review of the development of monodentate oxygen, nitrogen or carbon ligands (and their heavier congeners) bearing bulky organic substituents is given. It is shown that these versatile ligands have made an immense contribution to the development of modern inorganic and organometallic chemistry.
Co-reporter:Shirley Hino;Marcin Brynda Dr.;Andrew D. Phillips Dr.
Angewandte Chemie 2004 Volume 116(Issue 20) pp:
Publication Date(Web):5 MAY 2004
DOI:10.1002/ange.200353365
Demethylierung von [PbMe(2,6-Trip2C6H3)] (Trip=2,4,6-iPr3C6H2) mit Tris(perfluorphenyl)boran in Toluol ergibt [Pb(2,6-Trip2-C6H3)(η2-MeC6H5)][BMe(C6F5)3] (siehe Struktur). Das Bleizentrum ist durch eine Einfachbindung mit dem 2,6-Trip2C6H3-Liganden verknüpft und wird durch ein Toluolmolekül schwach solvatisiert.
Co-reporter:Shirley Hino;Marcin Brynda Dr.;Andrew D. Phillips Dr.
Angewandte Chemie International Edition 2004 Volume 43(Issue 20) pp:
Publication Date(Web):5 MAY 2004
DOI:10.1002/anie.200353365
Easily lead: The demethylation of [PbMe(2,6-Trip2C6H3)] (Trip=2,4,6-iPr3C6H2) with tris(perfluorophenyl)borane in toluene affords [Pb(2,6-Trip2C6H3)⋅(η2-MeC6H5)][B(Me)(C6F5)3] (see picture), in which the lead center is singly bound to the 2,6-Trip2C6H3 moiety and also weakly solvated by toluene.
Co-reporter:Corneliu Stanciu;Marilyn M. Olmstead;Andrew D. Phillips;Matthias Stender;Philip P. Power
European Journal of Inorganic Chemistry 2003 Volume 2003(Issue 18) pp:
Publication Date(Web):12 SEP 2003
DOI:10.1002/ejic.200300306
The very bulky phenols Ar*OH (1) and Ar′OH (2), where Ar* = C6H3-2,6-Trip2 (Trip = C6H2-2,4,6-iPr3) and Ar′ = C6H3-2,6-Dipp2 (Dipp = C6H3-2,6-iPr2), as well as their lithium and sodium derivatives (LiOAr*)2 (3), (LiOAr′)2 (4) and (NaOAr*)2 (5) have been synthesized and characterized. The terphenols 1 and 2 were obtained by the reaction of the aryllithium reagents with nitrobenzene and were isolated in ca. 70% yield. The lithium or sodium salts 3−5 were isolated by the reaction of 1 or 2 with nBuLi or sodium metal. All compounds were characterized spectroscopically, and by X-ray crystallography in the case of 1, 2, 4 and 5. The large terphenyl substituents prevent hydrogen-bonded association of the phenols 1 and 2. Instead, the O−H hydrogens interact with the π-electron cloud on one of the flanking Trip or Dipp rings. The dimeric structures of 4 and 5 are relatively rare examples of structurally characterized alkali metal phenoxides that are unsolvated by internal electron pair donors or classical Lewis bases such as ethers or amines. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)
Co-reporter:Anne F. Richards Dr.;Håkon Hope Dr. Dr.
Angewandte Chemie International Edition 2003 Volume 42(Issue 34) pp:
Publication Date(Web):5 SEP 2003
DOI:10.1002/anie.200351907
The first, well-characterized, polyhedral cluster with two different heavier group 14 elements is prepared (see picture). Low-valent group 14 halides are used to synthesize species in which the majority of the group 14 atoms carry no organic substituents.
Co-reporter:Anne F. Richards Dr.;Håkon Hope Dr. Dr.
Angewandte Chemie 2003 Volume 115(Issue 34) pp:
Publication Date(Web):5 SEP 2003
DOI:10.1002/ange.200351907
Zuverlässig charakterisiert wurde erstmals ein Polyedercluster mit zwei verschiedenen schweren Gruppe-14-Elementen (siehe Bild). Ausgangsverbindungen dieser Synthese sind niedervalente Gruppe-14-Halogenide; die vier Gruppe-14-Atome des Clusters tragen keine organischen Substituenten.
Co-reporter:Matthias Stender Dr.;Andrew D. Phillips Dr.;Robert J. Wright
Angewandte Chemie 2002 Volume 114(Issue 10) pp:
Publication Date(Web):15 MAY 2002
DOI:10.1002/1521-3757(20020517)114:10<1863::AID-ANGE1863>3.0.CO;2-I
Ge-Ge-Mehrfachbindungen: Die hier vorgestellte Verbindung, die in einer trans-abgewinkelten Struktur vorliegt (siehe Bild; Ge-Ge-C=128.67(8)°) und eine kurze Ge-Ge-Bindung aufweist (2.2850(5) Å), ist das erste stabile Digermanium-Analogon eines Alkins.
Co-reporter:Matthias Stender Dr.;Andrew D. Phillips Dr.;Robert J. Wright
Angewandte Chemie International Edition 2002 Volume 41(Issue 10) pp:
Publication Date(Web):15 MAY 2002
DOI:10.1002/1521-3773(20020517)41:10<1785::AID-ANIE1785>3.0.CO;2-6
Multiple Ge−Ge bonds: The title compound, which has a trans-bent structure (see structure; Ge-Ge-C=128.67(8)°) and a short Ge−Ge bond (2.2850(5) Å), is the first stable digermanium analogue of an alkyne.
Co-reporter:Ned J. Hardman Dr.;Robert J. Wright;Andrew D. Phillips Dr.
Angewandte Chemie International Edition 2002 Volume 41(Issue 15) pp:
Publication Date(Web):2 AUG 2002
DOI:10.1002/1521-3773(20020802)41:15<2842::AID-ANIE2842>3.0.CO;2-O
A GaGa bond order considerably less than unity in the “digallene” Ar′GaGaAr′ (Ar′=2,6-Dipp2C6H3, Dipp=2,6-iPr2C6H3; see structure) is indicated by its structure and solution behavior.
Co-reporter:Ned J. Hardman and Philip P. Power
Chemical Communications 2001 (Issue 13) pp:1184-1185
Publication Date(Web):13 Jun 2001
DOI:10.1039/B100466M
The reaction between {HC(MeCDippN)2}Ga: (Dipp = C6H3Pri2 -2,6) and N3SiMe3 afforded the tetrazole {HC(MeCDippN)2}GaN(SiMe3)NNN(SiMe3) 1 and its amide/azide isomer {HC(MeCDippN)2}Ga(N3)N(SiMe3) 2 2 whose stabilities are due to the unique steric properties of the [HC(MeCDippN)2]− ligand.
Co-reporter:Barrett E. Eichler Dr.
Angewandte Chemie 2001 Volume 113(Issue 4) pp:
Publication Date(Web):15 FEB 2001
DOI:10.1002/1521-3757(20010216)113:4<818::AID-ANGE8180>3.0.CO;2-0
Co-reporter:Ned J. Hardman;Chunming Cui Dr.;Herbert W. Roesky ;William H. Fink
Angewandte Chemie 2001 Volume 113(Issue 11) pp:
Publication Date(Web):28 MAY 2001
DOI:10.1002/1521-3757(20010601)113:11<2230::AID-ANGE2230>3.0.CO;2-N
Eine kurze Ga-N-Bindung mit Doppelbindungscharakter liegt beim ersten monomeren Galliumimid vor, das durch die Reaktion von [{HC(MeCDippN)2}M:] (Dipp=2,6-iPr2C6H3, M=Ga) mit N3-2,6-Trip2C6H3 (Trip=2,4,6-iPr3C6H2) hergestellt wurde (siehe Bild). Die analoge Aluminiumverbindung (M=Al) ist ebenfalls leicht herstellbar.
Co-reporter:Ned J. Hardman, Barrett E. Eichler and Philip P. Power
Chemical Communications 2000 (Issue 20) pp:1991-1992
Publication Date(Web):27 Sep 2000
DOI:10.1039/B005686N
The reaction between solvent free
Li{(NDippCMe)2CH} (Dipp =
C6H3Pri2-2,6),
‘GaI’ and potassium in toluene afforded
Ga{(NDippCMe)2CH}
1 which features a V-shaped,
two-coordinate, six-electron gallium(I) center electronically
analogous to a singlet carbene carbon.
Co-reporter:Brendan Twamley, Cheong-Soo Hwang, Ned J Hardman, Philip P Power
Journal of Organometallic Chemistry 2000 Volume 609(1–2) pp:152-160
Publication Date(Web):8 September 2000
DOI:10.1016/S0022-328X(00)00162-5
A series of sterically crowded primary pnictanes of formula ArEH2 (Ar=C6H3-2,6-Trip2; Trip=C6H2-2,4,6-i-Pr3; E=N, 2; P, 4; As, 5; Sb, 6) and their lithiated pnictide salts ArE(H)Li (E=N, 7; P, 8; As, 9; Sb, 10) have been synthesized and characterized by X-ray crystallography (2-6), NMR, IR spectroscopy, and by combustion analysis. Details of the synthesis and structures of the azide derivative ArN3 (1) and the arylphosphinic acid ArP(O)(OH)H (3) are also given. The amine compound 2 displays a planar geometry (within the limits of experimental error) at nitrogen which is attributable to interactions between the NH moieties and the ortho-aryl rings. The antimony compound 6 is a rare instance of a stable primary stibane and its X-ray crystal structure represents the first structural determination of such a species.
Co-reporter:Barrett E. Eichler Dr.;Ned J. Hardman
Angewandte Chemie 2000 Volume 112(Issue 2) pp:
Publication Date(Web):12 JAN 2000
DOI:10.1002/(SICI)1521-3757(20000117)112:2<391::AID-ANGE391>3.0.CO;2-J
Ein verzerrter In8-Cubankern (siehe Bild) liegt im neuen Indiumcluster In8(C6H3-2,6-Mes2)4 (Mes=C6H2-2,4,6-Me3) vor, der durch die Reaktion von LiC6H3-2,6-Mes2 mit InCl synthetisiert wurde. Die durchschnittliche In-In-Bindungslänge in dieser Verbindung, die die Gruppe der Cluster von schwereren Elementen der 13. Gruppe bereichert, beträgt 2.92 Å.
Co-reporter:Brendan Twamley Dr.;Philip P. Power
Angewandte Chemie 2000 Volume 112(Issue 19) pp:
Publication Date(Web):26 SEP 2000
DOI:10.1002/1521-3757(20001002)112:19<3643::AID-ANGE3643>3.0.CO;2-Q
Co-reporter:Barrett E. Eichler Dr.;Ned J. Hardman
Angewandte Chemie International Edition 2000 Volume 39(Issue 2) pp:
Publication Date(Web):12 JAN 2000
DOI:10.1002/(SICI)1521-3773(20000117)39:2<383::AID-ANIE383>3.0.CO;2-Q
A distorted In8cubane core (see picture) is present in the novel indium cluster In8(C6H3-2,6-Mes2)4 (Mes=C6H2-2,4,6-Me3), which was synthesized by the reaction of LiC6H3-2,6-Mes2 with InCl. It has an average In−In bond length of 2.92 Å and represents a new addition to the range of heavier Group 13 element clusters.
Co-reporter:Ned J. Hardman;Brendan Twamley Dr.;Philip P. Power
Angewandte Chemie 2000 Volume 112(Issue 15) pp:
Publication Date(Web):2 AUG 2000
DOI:10.1002/1521-3757(20000804)112:15<2884::AID-ANGE2884>3.0.CO;2-E
Co-reporter:Rudolf J. Wehmschulte;Philip P. Power
Angewandte Chemie 1998 Volume 110(Issue 22) pp:
Publication Date(Web):12 MAR 1999
DOI:10.1002/(SICI)1521-3757(19981116)110:22<3344::AID-ANGE3344>3.0.CO;2-A
Über das Ga4-Gerüst delokalisiert sind die beiden Elektronen in Na2[Ga(GaTrip2)3], die bei der Oxidation zu Ga(GaTrip2)3 abgegeben werden. Die Ga-Ga-Bindungslänge verlängert sich dabei um 0.08 Å. Ar=2,4,6-iPr3C6H2 (Trip).
Co-reporter:Rudolf. J. Wehmschulte
Angewandte Chemie International Edition 1998 Volume 37(Issue 22) pp:
Publication Date(Web):17 DEC 1998
DOI:10.1002/(SICI)1521-3773(19981204)37:22<3152::AID-ANIE3152>3.0.CO;2-7
Delocalized over the Ga4framework, the two electrons are lost in the oxidation of Na2[Ga(GaTrip2)3] to Ga(GaTrip2)3. This leads to a lengthening of the Ga−Ga bond by about 0.08 Å. Ar=Trip=2,4,6-iPr3C6H2.
Co-reporter:Xinping Wang ; Zhongliang Zhu ; Yang Peng ; Hao Lei ; James C. Fettinger
Journal of the American Chemical Society () pp:
Publication Date(Web):May 4, 2009
DOI:10.1021/ja9017286
Reactions of the heteroleptic diarylgermylenes GeAr#(Ar′) (1) or GeAr# (Ar*-3,5-Pri2) (2) (Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2; Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2; Ar*-3,5-Pri2 = C6H-2,6-(C6H2-2,4,6-Pri3)2-3,5-Pri2) with carbon monoxide at room temperature gave α-germyloxy ketones via double CO insertion into the Ge−Ar′ carbon bond in 1 and the Ge−Ar# bond in 2. The Ar#Ge-OCC(O)Ar′ and 3,5-Pri2Ar*Ge-O-CC(O)Ar# intermediates that are formed are unstable and rearrange via the insertion of the carbon of the GeOC moiety into a methyl−aryl or isopropyl carbon to form six-membered ring products.
Co-reporter:Ned J. Hardman, Philip P. Power, John D. Gorden, Charles L. B. Macdonald and Alan H. Cowley
Chemical Communications 2001(Issue 18) pp:NaN1867-1867
Publication Date(Web):2001/08/29
DOI:10.1039/B106599H
Examples of compounds with gallium–boron donor–acceptor bonds, HC[MeC(2,6-Pri2C6H3)N]2Ga→B(C6F5)33 and (η5-C5Me5)Ga→B(C6F5)34 have been prepared by treatment of the free gallanediyls with B(C6F5)3; the structures of both compounds were determined by X-ray crystallography.
Co-reporter:Matthias Stender, Andrew D. Phillips and Philip P. Power
Chemical Communications 2002(Issue 12) pp:NaN1313-1313
Publication Date(Web):2002/05/20
DOI:10.1039/B203403D
The reduction of Ar*GeCl (Ar* = C6H3-2,6-Trip2; Trip = C6H2-2,4,6-i-Pr3) with one equivalent of potassium leads to the formation of a germanium analogue of an alkyne Ar*GeGeAr* 1; reaction of 1 with 2,3-dimethyl-1,3-butadiene yields [Ar*Ge{CH2C(Me)C(Me)CH2}CH2C(Me)]22, which was structurally characterized.
Co-reporter:Ningning Yuan, Wenqing Wang, Ziye Wu, Sheng Chen, Gengwen Tan, Yunxia Sui, Xinping Wang, Jun Jiang and Philip P. Power
Chemical Communications 2016 - vol. 52(Issue 86) pp:NaN12716-12716
Publication Date(Web):2016/09/23
DOI:10.1039/C6CC06918E
A boron radical contact ion-pair Mes2B{4-(3,5-dimethylpyridinyl)}K(18-crown-6)(THF) (1K) has been isolated and characterized by electron paramagnetic resonance (EPR) spectroscopy, UV-vis absorption spectroscopy and single crystal X-ray diffraction. The geometry, bonding and spin density distribution are shown to be affected by the N⋯K interaction. The unpaired electron resides mainly on the boron atom and falls between those of triarylboron radical anions and neutral boron radicals. The work provides a novel boron-centered radical intermediate, connecting anionic and neutral boryl radicals.
Co-reporter:Jeremy D. Erickson, Ting Yi Lai, David J. Liptrot, Marilyn M. Olmstead and Philip P. Power
Chemical Communications 2016 - vol. 52(Issue 94) pp:NaN13659-13659
Publication Date(Web):2016/09/22
DOI:10.1039/C6CC06963K
The facile heterodehydrocoupling of a range of primary or secondary amines and even ammonia with pinacolborane (HBPin) was accomplished using {ArMe6Sn(μ-OMe)}2 (1, ArMe6 = C6H3-2,6-(C6H2-2,4,6-Me3)2) as pre-catalysts for a catalytically active tin(II) hydride. The more sterically hindered pre-catalyst 2, {AriPr4Sn(μ-OMe)}2 (AriPr4 = C6H3-2,6-(C6H3-2,6-iPr2)2) facilitated the dehydrocoupling only of primary amines with HBPin, and at an increased rate relative to the less crowded {ArMe6Sn(μ-OMe)}2. Also presented is {ArMe6Sn(μ-NEt2)}2 (3), which can be converted into the structurally characterizable {ArMe6Sn(μ-NEt2)(μ-H)SnArMe6} (4) via the addition of pinacol borane. This, alongside stoichiometric studies, give insight into the mechanism of the catalysis.
Co-reporter:Yuanting Su, Xingyong Wang, Lei Wang, Zaichao Zhang, Xinping Wang, You Song and Philip P. Power
Chemical Science (2010-Present) 2016 - vol. 7(Issue 10) pp:NaN6518-6518
Publication Date(Web):2016/06/28
DOI:10.1039/C6SC01825D
Diradicals, molecules with two unpaired electrons, are reactive intermediates that play an important role in many fields. Their defining feature is the energy difference between their singlet and triplet states, which provides direct information on the extent of their electron exchange interactions. Such knowledge is essential for understanding their diradical character, which is controllable internally by modification of the electronic and steric properties of the substituents. We now report that the energy gap of a diradical in the solid state can also be controlled by an external stimulus. The dication diradical of 4,4′′-di(bisphenylamino)-p-terphenyl exhibits two singlet states with different exchange coupling constants at different temperatures as determined by SQUID and EPR measurements. The behavior is induced by the conformation change of the terphenyl bridge, the key structural unit of the species. The work presents an unprecedented instance of a thermally controllable singlet–triplet gap for a crystalline diradical and provides a novel diradical material relevant to the design of functional materials.
Co-reporter:C.-Y. Lin, J. C. Fettinger, N. F. Chilton, A. Formanuik, F. Grandjean, G. J. Long and P. P. Power
Chemical Communications 2015 - vol. 51(Issue 68) pp:NaN13278-13278
Publication Date(Web):2015/07/07
DOI:10.1039/C5CC05166E
The reduction of Mn{C(SiMe3)3}2 with KC8 in the presence of crown ethers yielded the d6, Mn(I) salts [K2(18-crown-6)3][Mn{C(SiMe3)3}2]2 and [K(15-crown-5)2][Mn{C(SiMe3)3}2], that have near-linear manganese coordination but almost completely quenched orbital magnetism as a result of 4s–3dz2 orbital mixing which affords a non-degenerate ground state.
Co-reporter:Felicitas Lips, Joshua D. Queen, James C. Fettinger and Philip P. Power
Chemical Communications 2014 - vol. 50(Issue 42) pp:NaN5564-5564
Publication Date(Web):2014/04/02
DOI:10.1039/C4CC00999A
Reactions of the tetrylenes Ge(SArMe6)2 (1) (ArMe6 = C6H3-2,6(C6H2-2,4,6-Me3)2), and Sn(SArMe6)2 (2) with (Mo(CO)4(NBD) (NBD = bicyclo[2.2.1]hepta-2,5-diene) gave three new, unusual complexes [Mo(THF)(CO)3{Ge(SArMe6)2}] (3), [Mo(THF)(CO)3{Ge(SArMe6)2}] (4) and [Mo(CO)4{Sn(SArMe6)2}] (5) which display no significant Ge/Sn–Mo bonding. Instead the ligands are coordinated to molybdenum in a bidentate fashion via the thiolato sulfurs.
Co-reporter:Christine A. Caputo, Zhongliang Zhu, Zachary D. Brown, James C. Fettinger and Philip P. Power
Chemical Communications 2011 - vol. 47(Issue 26) pp:NaN7508-7508
Publication Date(Web):2011/05/31
DOI:10.1039/C1CC11676B
The reactions of Ar′GaGaAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) with alkenes revealed the addition of two olefins per Ar′GaGaAr′ under ambient conditions for ethylene, propene, 1-hexene and styrene but no reactions with more hindered or cyclic olefins.
Co-reporter:Mario Carrasco, Michelle Faust, Riccardo Peloso, Amor Rodríguez, Joaquín López-Serrano, Eleuterio Álvarez, Celia Maya, Philip P. Power and Ernesto Carmona
Chemical Communications 2012 - vol. 48(Issue 33) pp:NaN3956-3956
Publication Date(Web):2012/02/28
DOI:10.1039/C2CC30394A
New quadruply bonded dimolybdenum complexes of the terphenyl ligand ArXyl2 (ArXyl2 = C6H3-2,6-(C6H3-2,6-Me2)2) have been prepared and structurally characterized. The steric hindrance exerted by the ArXyl2 groups causes the Mo atoms to feature unsaturated four-coordinate structures and a formal fourteen-electron count.
Co-reporter:Chengbao Ni, Bobby D. Ellis, Gary J. Long and Philip P. Power
Chemical Communications 2009(Issue 17) pp:NaN2334-2334
Publication Date(Web):2009/03/25
DOI:10.1039/B901494B
Reaction of Ar′CrCrAr′ (Ar′ = C6H3-2,6-(C6H3-2,6-Pri2)2) with heterocumulene reagents N2O or N3(1-Ad) resulted in Ar′Cr(μ-O)2Cr(O)Ar′ or Ar′Cr(μ2:η1,η3-N3(1-Ad))CrAr′ which have no metal–metal bonding.
Co-reporter:Chengbao Ni and Philip P. Power
Chemical Communications 2009(Issue 37) pp:NaN5545-5545
Publication Date(Web):2009/08/17
DOI:10.1039/B912312A
The iron(II) diaryl FeAr′2 (1) (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) reacts cleanly with O2 or CO to afford the monomeric, two-coordinate bis(aryloxide) Fe(OAr′)2 (2) or the η2-acyl–carbonyl complex (η2-Ar′CO)2Fe(CO)2 (3) viaoxygen or CO insertion into the Fe–C bonds; complex 2 has a strictly linear geometry and shows remarkable resistance to O2oxidation.
Co-reporter:Andrew D. Sutton, Benjamin L. Davis, Koyel X. Bhattacharyya, Bobby D. Ellis, John C. Gordon and Philip P. Power
Chemical Communications 2010 - vol. 46(Issue 1) pp:NaN149-149
Publication Date(Web):2009/11/13
DOI:10.1039/B919383A
The use of benzenedithiol as a digestant for ammonia–borane spent fuel has been shown to result in tin thiolate compounds which we demonstrate can be recycled, yielding Bu3SnH and ortho-benzenedithiol for reintroduction to the ammonia–borane regeneration scheme.
Co-reporter:Yang Peng, Xinping Wang, James C. Fettinger and Philip P. Power
Chemical Communications 2010 - vol. 46(Issue 6) pp:NaN945-945
Publication Date(Web):2010/01/08
DOI:10.1039/B919828H
The reaction of the distannyne Ar′SnSnAr′ (Ar′ = C6H3-2,6(C6H3-2,6-iPr2)2) with tert-butyl or mesityl isocyanide afforded the bis-adducts Ar′SnSnAr′(CNBut)2 or Ar′SnSnAr′ (CNMes)2 in which the isonitriles are reversibly bound under ambient conditions.
Co-reporter:Chengbao Ni, Troy A. Stich, Gary J. Long and Philip P. Power
Chemical Communications 2010 - vol. 46(Issue 25) pp:NaN4468-4468
Publication Date(Web):2010/05/20
DOI:10.1039/C001483D
The synthesis and characterization of two-coordinate cobalt(II) complexes CoAr′2 (1) and Ar′CoN(SiMe3)2 (2) (Ar′ = C6H3-2,6-(C6H3-2,6-iPr2)2) are reported. The magnetic data for 2 show that it has an unexpectedly high μeff of 5.65 μB whereas the bent complex 1 has a significantly lower moment.
Co-reporter:Yang Peng, Marcin Brynda, Bobby D. Ellis, James C. Fettinger, Eric Rivard and Philip P. Power
Chemical Communications 2008(Issue 45) pp:NaN6044-6044
Publication Date(Web):2008/10/17
DOI:10.1039/B813442A
Dihydrogen reacts directly with a range of distannynes at ca. 25 °C under one atmosphere pressure to afford symmetric hydrogen bridged or unsymmetric stannylstannane products in high yield.
Co-reporter:Chengbao Ni, James C. Fettinger, Gary J. Long, Marcin Brynda and Philip P. Power
Chemical Communications 2008(Issue 45) pp:NaN6047-6047
Publication Date(Web):2008/10/21
DOI:10.1039/B810941A
Reaction of 3,5-Pri2Ar*Fe(η6-C6H6)(3,5-Pri2Ar* = C6H1-2,6-(C6H2-2,4,6-Pri3)2-3,5-Pri2) with N3C6H3-2,6-Mes2 (Mes = C6H2-2,4,6-Me3) afforded the dimeric iron(II) amido/aryl complex {CH2C6H2-2(C6H3-2-N(H)FeAr*-3,5-Pri2)-3,5-Me2}2 (1) which arises viamethyl hydrogen abstraction by nitrogen and dimerization of the radical via C–C bond formation; in contrast, reaction of 3,5-Pri2Ar*Fe(η6-C6H6) with N3(1-Ad) (1-Ad = 1-adamantanyl) gave the iron(V) bis(imido) complex 3,5-Pri2Ar*Fe{N(1-Ad)}2 (2).
Co-reporter:Geoffrey H. Spikes and Philip P. Power
Chemical Communications 2007(Issue 1) pp:NaN87-87
Publication Date(Web):2006/10/19
DOI:10.1039/B612202G
The reaction of the “digermyne” Ar′GeGeAr′ (Ar′ = C6H3–2,6(C6H3–2,6-Pri2)2; Ge–Ge = 2.2850(6) Å) with mesityl isocyanide affords the bis adduct [Ar′GeGeAr′(CNMes)2] which results in the conversion of a Ge–Ge multiple bond to a long Ge–Ge single bond (= 2.6626(8) Å).
Co-reporter:Jing-Dong Guo, David J. Liptrot, Shigeru Nagase and Philip P. Power
Chemical Science (2010-Present) 2015 - vol. 6(Issue 11) pp:NaN6244-6244
Publication Date(Web):2015/08/19
DOI:10.1039/C5SC02707A
The structures and bonding in the heavier group 14 element olefin analogues [E{CH(SiMe3)2}2]2 and [E{N(SiMe3)2}2]2 (E = Ge, Sn, or Pb) and their dissociation into :E{CH(SiMe3)2}2 and :E{N(SiMe3)2}2 monomers were studied computationally using hybrid density functional theory (DFT) at the B3PW91 with basis set superposition error and zero point energy corrections. The structures were reoptimized with the dispersion-corrected B3PW91-D3 method to yield dispersion force effects. The calculations generally reproduced the experimental structural data for the tetraalkyls with a few angular exceptions. For the alkyls, without the dispersion corrections, dissociation energies of −2.3 (Ge), +2.1 (Sn), and −0.6 (Pb) kcal mol−1 were calculated, indicating that the dimeric E–E bonded structure is favored only for tin. However, when dispersion force effects are included, much higher dissociation energies of 28.7 (Ge), 26.3 (Sn), and 15.2 (Pb) kcal mol−1 were calculated, indicating that all three E–E bonded dimers are favored. Calculated thermodynamic data at 25 °C and 1 atm for the dissociation of the alkyls yield ΔG values of 9.4 (Ge), 7.1 (Sn), and −1.7 (Pb) kcal mol−1, indicating that the dimers of Ge and Sn, but not Pb, are favored. These results are in harmony with experimental data. The dissociation energies for the putative isoelectronic tetraamido-substituted dimers [E{N(SiMe3)2}2]2 without dispersion correction are −7.0 (Ge), −7.4 (Sn), and −4.8 (Pb) kcal mol−1, showing that the monomers are favored in all cases. Inclusion of the dispersion correction yields the values 3.6 (Ge), 11.7 (Sn), and 11.8 (Pb) kcal mol−1, showing that dimerization is favored but less strongly so than in the alkyls. The calculated thermodynamic data for the amido germanium, tin, and lead dissociation yield ΔG values of −12.2, −3.7, and −3.6 kcal mol−1 at 25 °C and 1 atm, consistent with the observation of monomeric structures. Overall, these data indicate that, in these sterically-encumbered molecules, dispersion force attraction between the ligands is of greater importance than group 14 element–element bonding, and is mainly responsible for the dimerization of the metallanediyls species to give the dimetallenes. In addition, calculations on the non-dissociating distannene [Sn{SiMetBu2}2]2 show that the attractive dispersion forces are key to its stability.
Co-reporter:Alexandra L. Pickering, Christoph Mitterbauer, Nigel D. Browning, Susan M. Kauzlarich and Philip P. Power
Chemical Communications 2007(Issue 6) pp:NaN582-582
Publication Date(Web):2007/01/11
DOI:10.1039/B614363F
Capped boron nanoparticles have been synthesized at room temperature by a simple route that does not involve the use of flammable boranes.
Co-reporter:Nicholas F. Chilton, Hao Lei, Aimee M. Bryan, Fernande Grandjean, Gary J. Long and Philip P. Power
Dalton Transactions 2015 - vol. 44(Issue 24) pp:NaN11211-11211
Publication Date(Web):2015/05/18
DOI:10.1039/C5DT01589H
The 2 to 300 K magnetic susceptibilities of Fe{N(SiMe2Ph)2}2, 1, Fe{N(SiMePh2)2}2, 2, and the diaryl complex Fe(ArPri4)2, 3, where ArPri4 is C6H3-2,6(C6H3-2,6-Pri2)2 have been measured. Initial fits of these properties in the absence of an independent knowledge of their ligand field splitting have proven problematic. Ab initio calculations of the CASSCF/RASSI/SINGLE-ANISO type have indicated that the orbital energies of the complexes, as well as those of Fe(ArMe6)2, 4, where ArMe6 is C6H3-2,6(C6H2-2,4,6-Me3)2), are in the order dxy ≈ dx2−y2 < dxz ≈ dyz < dz2, and the iron(II) complexes in this ligand field have the (dxy, dx2−y2)3(dxz, dyz)2(dz2)1 ground electronic configuration with a substantial orbital contribution to their effective magnetic moments. An ab initio-derived ligand field and spin–orbit model is found to yield an excellent simulation of the observed magnetic properties of 1–3. The calculated ligand field strengths of these ligands are placed in the broader context of common coordination ligands in hypothetical two-coordinate linear iron(II) complexes. This yields the ordering I− < H− < Br− ≈ PMe3 < CH3− < Cl− ≈ C(SiMe3)3− < CN− ≈ SArPri6− < ArPri4− < ArMe6− ≈ N3− < NCS− ≈ NCSe− ≈ NCBH3− ≈ MeCN ≈ H2O ≈ NH3 < NO3− ≈ THF ≈ CO ≈ N(SiMe2Ph)2− ≈ N(SiMePh2)2− < F− ≈ N(H)ArPri6− ≈ N(SiMe3)Dipp− < OArPri4−. The magnetic susceptibility of the bridged dimer, [Fe{N(SiMe3)2}2]2, 5, has also been measured between 2 and 300 K and a fit of χMT with the isotropic Heisenberg Hamiltonian, Ĥ = −2JŜ1·Ŝ2 yields an antiferromagnetic exchange coupling constant, J, of −131(2) cm−1.
Co-reporter:Chengbao Ni, Brian Rekken, James C. Fettinger, Gary J. Long and Philip P. Power
Dalton Transactions 2009(Issue 39) pp:NaN8355-8355
Publication Date(Web):2009/08/21
DOI:10.1039/B911978G
The synthesis and characterization of the mononuclear manganese primary amido complex Mn{N(H)Ar#}2 (1), its Lewis base adducts Mn{N(H)Ar#}2(L) (Ar# = C6H3-2,6-(C6H2-2,4,6-Me3)2; L = THF (2), and C5H5N (3)), and Mn{N(H)Ar*}2 (4) (Ar* = C6H3-2,6-(C6H2-2,4,6-iPr3)2) are described. Complex 1 was prepared by the reaction of MnCl2 with two equivalents of LiN(H)Ar# in benzene. X-Ray crystallography showed that it had a quasi-two-coordinate strongly bent geometry with Mn–N = 1.979(3) Å, N–Mn–N = 138.19(9)° and secondary Mn⋯C(aryl ring) interactions. In contrast, complex 4, which was prepared by the same route as 1, has an almost linear geometry with a wide N–Mn–N angle of 176.1(2)°. The complexes 1 and 4 are the first structurally characterized homoleptic primary amido derivatives of manganese. Complex 1 did not react with THF or pyridine, but its THF complex 2 could be formed by the reaction of MnI2(THF)2 with two equivalents of LiN(H)Ar#. Similarly, complex 3 was prepared either by the direct reaction of MnCl2 with LiN(H)Ar# in hexanes in the presence of pyridine, or by reaction of the THF complex 2 with excess pyridine. Attempts to form Lewis base complexes of 4 by similar routes led to the recovery of unreacted 4. The results suggested that reaction with Lewis bases is prevented by secondary interactions (1) or steric effects (4). Magnetic studies show that the manganese(II) ions in 1–4 have high spin configurations with S = and small zero-field splittings, D, of ca.±1.5 to ±3 cm−1.
Co-reporter:Chengbao Ni, James C. Fettinger, Gary J. Long and Philip P. Power
Dalton Transactions 2010 - vol. 39(Issue 44) pp:NaN10670-10670
Publication Date(Web):2010/10/06
DOI:10.1039/C0DT00771D
Reaction of {Li(THF)Ar′MnI2}2 (Ar′ = C6H3-2,6-(C6H2-2,6-iPr3)2) with LiAr′, LiCCR (R = tBu or Ph), or (C6H2-2,4,6-iPr3)MgBr(THF)2 afforded the diaryl MnAr′2 (1), the alkynyl salts Ar′Mn(CCtBu)4{Li(THF)}3 (2) and Ar′Mn(CCPh)3Li3(THF)(Et2O)2(μ3-I) (3), and the manganate salt {Li(THF)}Ar′Mn(μ-I)(C6H2-2,4,6-iPr3) (4), respectively. Complex 4 reacted with one equivalent of (C6H2-2,4,6-iPr3)MgBr(THF)2 to afford the homoleptic dimer {Mn(C6H2-2,4,6-iPr3)(μ-C6H2-2,4,6-iPr3)}2 (5), which resulted from the displacement of the bulkier Ar′ ligand in preference to the halogen. The reaction of the more crowded {Li(THF)Ar*MnI2}2 (Ar* = C6H3-2,6-(C6H2-2,4,6-iPr3)2) with LitBu gave complex Ar*MntBu (6). Complex 1 is a rare monomeric homoleptic two-coordinate diaryl Mn(II) complex; while 6 displays no tendency to eliminate β-hydrogens from the tBu group because of the stabilization supplied by Ar*. Compounds 2 and 3 have cubane frameworks, which are constructed from a manganese, three carbons from three acetylide ligands, three lithiums, each coordinated by a donor, plus either a carbon from a further acetylide ligand (2) or an iodide (3). The Mn(II) atom in 4 has an unusual distorted T-shaped geometry while the dimeric 5 features trigonal planar manganese coordination. The chloride substituted complex Li2(THF)3{Ar′MnCl2}2 (7), which has a structure very similar to that of {Li(THF)Ar′MnI2}2, was also prepared for use as a possible starting material. However, its generally lower solubility rendered it less useful than the iodo salt. Complexes 1–7 were characterized by X-ray crystallography and UV-vis spectroscopy. Magnetic studies of 2–4 and 6 showed that they have 3d5 high-spin configurations.
Co-reporter:Chengbao Ni, Bobby D. Ellis, Troy A. Stich, James C. Fettinger, Gary J. Long, R. David Britt and Philip P. Power
Dalton Transactions 2009(Issue 27) pp:NaN5405-5405
Publication Date(Web):2009/05/26
DOI:10.1039/B904647J
The reduction of {ArFeBr}2 (Ar = terphenyl) with KC8 in the presence of excess PMe3 afforded the Fe(I) complex 3,5-Pri2-Ar′Fe(PMe3) (1) (Ar′-3,5-Pri2 = C6H-2,6-(C6H3-2,6-Pri2)-3,5-Pri2), which has a structure very different from the previously reported, linear Cr(I) species 3,5-Pri2-Ar*Cr(PMe3) (3,5-Pri2-Ar* = C6H-2,6-(C6H2–2,4,6-Pri3)2–3,5-Pri2) and features a strong Fe-η6-aryl interaction with the flanking aryl ring of the terphenyl ligand. In sharp contrast, the reduction of {ArCoCl}2 (Ar = 3,5-Pri2-Ar′ and Ar′) afforded the allyl complexes Co(η3-{1-(H2C)2C-C6H3–2-(C6H2–2,4-Pri2–5-(C6H3–2,6-Pri2))-3-Pri})(PMe3)3 (4) and Co(η3-{1-(H2C)2C-C6H3–2-(C6H4–3-(C6H3–2,6-Pri2))-3-Pri})(PMe3)3 (5) formed by an unusual triple dehydrogenation of an isopropyl group. It is proposed that the reduction initially generates an intermediate 3,5-Pri2-Ar′Co(PMe3), which is similar in structure to 1, followed by 3,5-Pri2-Ar′Co(PMe3) decomposition to a cobalt hydride intermediate and dehydrogenation of the isopropyl groupvia remote C–H activation induced by PMe3 complexation. Complexes 1, 4, and 5 were characterized by X-ray crystallography. In addition, 1 was studied by NMR and EPR spectroscopy; 4 and 5 were characterized by NMR spectroscopy.
Co-reporter:Eric Rivard and Philip P. Power
Dalton Transactions 2008(Issue 33) pp:NaN4343-4343
Publication Date(Web):2008/07/24
DOI:10.1039/B801400K
This Perspective discusses the synthesis and reactivity of low valent Group 14 hydrides of germanium and tin. The use of hindered terphenyl ligands has facilitated the isolation of a number of unusual new main group hydride structural types (each predicted by computational work), and has culminated in the use of these species as precursors to new cluster archetypes.
Co-reporter:Yang Peng, Roland C. Fischer, W. Alexander Merrill, Jelena Fischer, Lihung Pu, Bobby D. Ellis, James C. Fettinger, Rolfe H. Herber and Philip P. Power
Chemical Science (2010-Present) 2010 - vol. 1(Issue 4) pp:NaN468-468
Publication Date(Web):2010/06/18
DOI:10.1039/C0SC00240B
The synthesis and characterization of a series of digermynes and distannynes stabilized by terphenyl ligands are described. The ligands are based on the Ar′ (Ar′ = C6H3-2,6(C6H3-2,6-iPr2)2) or Ar* (Ar* = C6H3-2,6(C6H2-2,4,6-iPr3)2) platforms which were modified at the meta or para positions of their central aryl rings to yield 4-X-Ar′ (4-X-Ar′ = 4-X-C6H2-2,6(C6H3-2,6-iPr2)2, X = H, F, Cl, OMe, tBu, SiMe3, GeMe3) and 3,5-iPr2-Ar′ or Ar* and 3,5-iPr2-Ar*. The compounds were synthesized by reduction of the terphenyl germanium(II) or tin(II) halide precursors with a variety of reducing agents. The precursors were obtained by the reaction of one equivalent of the lithium terphenyl with GeCl2 dioxane or SnCl2. For germanium, their X-ray crystal structures showed them to be either Ge–Ge bonded dimers with trans-pyramidal geometries or V-shaped monomers. In contrast, the terphenyl tin halides had no tin–tin bonding but existed either as halide bridged dimers or V-shaped monomers. Reduction with a variety of reducing agents afforded the digermynes ArGeGeAr (Ar = 4-Cl-Ar′, 4-SiMe3-Ar′ or 3,5-iPr2-Ar*) or the distannynes ArSnSnAr (Ar = 4-F-Ar′, 4-Cl-Ar′, 4-MeO-Ar′, 4-tBu-Ar′, 4-SiMe3-Ar′, 4-GeMe3-Ar′, 3,5-iPr2-Ar′, 3,5-iPr2-Ar*), which were characterized structurally and spectroscopically. The digermynes display planar trans-bent core geometries with Ge–Ge distances near 2.26 Å and bending angles near 128° consistent with Ge–Ge multiple bonding. In contrast, the distannynes had either multiple bonded geometries with Sn–Sn distances that averaged 2.65 Å and an average bending angle near 123.8°, or single bonded geometries with a Sn–Sn bond length near 3.06 Å and a bending angle near 98°. The 3,5-iPr2-Ar*SnSnAr*-3,5-iPr2 species had an intermediate structure with a longer multiple bond near 2.73 Å and a variable torsion angle (14–28°) between the tin coordination planes. Mössbauer data for the multiple and single bonded species displayed similar isomer shifts but had different quadrupole splittings.
Co-reporter:Eric Rivard, Jochen Steiner, James C. Fettinger, Jason R. Giuliani, Matthew P. Augustine and Philip P. Power
Chemical Communications 2007(Issue 46) pp:NaN4921-4921
Publication Date(Web):2007/09/24
DOI:10.1039/B709446A
Two complementary synthetic routes to a pentagonal bipyramidal Sn7 cluster, Sn7Aryl2 (Aryl = terphenyl ligand), are reported.
Co-reporter:W. Alexander Merrill, Jochen Steiner, Audra Betzer, Israel Nowik, Rolfe Herber and Philip P. Power
Dalton Transactions 2008(Issue 43) pp:NaN5910-5910
Publication Date(Web):2008/09/11
DOI:10.1039/B809671F
The primary tin(II) amido derivatives Sn2{N(H)Dipp}4 (1) and Sn2{N(H)Dipp}3Cl (2) (Dipp = C6H3-2,6-Pri2) have been prepared and characterized. Compound 1 was obtained by the transamination of Sn{N(SiMe3)2}2 with H2NDipp in a 1:2 ratio or by the reaction of two equivalents of LiN(H)Dipp with SnCl2. The attempted preparation of Sn(Cl){N(H)Dipp} by reaction of LiN(H)Dipp with SnCl2 in a 1:1 ratio led to the isolation of the unique species Sn2{N(H)Dipp}3Cl, which is the first example of a sesqui-amido derivative of a group 14 element. Both 1 and 2 were characterized by 1H and 119Sn NMR spectroscopy, X-ray crystallography and Mössbauer spectroscopy. The structures of 1 and 2 feature two tin centers bridged by –N(H)Dipp ligands with the terminal positions being occupied by two N(H)Dipp (1) or –N(H)Dipp and –Cl (2) groups. The compound 1 was found to be unstable under ambient conditions and spontaneously converts to the imide tetramer (SnNDipp)4 in solution over several days at room temperature, representing a new synthetic route to group 14 element imides.
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