Trevor W. Hayton

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Name: Hayton, Trevor W.

Organization: University of California Santa Barbara , USA

Department: Department of Chemistry and Biochemistry

Title: Professor(PhD)

TOPICS

Inorganic Chemistry

Chemicals
References

Subnanometer-Sized Copper Clusters: A Critical Re-evaluation of the Synthesis and Characterization of Cu8(MPP)4 (HMPP = 2-Mercapto-5-n-propylpyrimidine)

Co-reporter:Thuy-Ai D. Nguyen, Andrew W. Cook, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry July 17, 2017 Volume 56(Issue 14) pp:8390-8390

Publication Date(Web):June 28, 2017

DOI:10.1021/acs.inorgchem.7b01062

We report a critical re-evaluation of the synthesis and characterization of Cu8(MPP)4. This product was reportedly formed by the reaction of Cu(NO3)2 with 2-mercapto-5-n-propylpyrimidine (HMPP) and NaBH4, in ethanol, in the presence of [N(C8H17)4][Br]. In our hands, we found no experimental evidence to support the existence of Cu8(MPP)4 in the reaction mixture. Instead, we demonstrate that the material isolated from this reaction is a complex mixture containing [N(C8H17)4]+, Br–, NO3–, and 2-mercapto-5-n-propyl-1,6-dihydropyrimidine (H2MPP*), along with the Cu(I) coordination polymer, [Cu(MPP)]n. To support our conclusions, we have independently synthesized H2MPP* and [Cu(MPP)]n, as well as the related Cu(I) coordination complexes, [Cu(HMPP*)]n and [Cu2(MPP*)]n. All new materials were characterized by NMR spectroscopy and mass spectrometry, while H2MPP*, [Cu(HMPP*)]n (n = 4), and [Cu(MPP)]n (n = 6) were also characterized by X-ray crystallography.

Reversible Chalcogen-Atom Transfer to a Terminal Uranium Sulfide

Co-reporter:Danil E. Smiles, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry December 15, 2014 Volume 53(Issue 24) pp:

Publication Date(Web):December 1, 2014

DOI:10.1021/ic502500z

The reaction of elemental S or Se with [K(18-crown-6)][U(S)(NR2)3] (1) results in the formation of the new uranium(IV) dichalcogenides [K(18-crown-6)][U(η2-S2)(NR2)3] (2) and [K(18-crown-6)][U(η2-SSe)(NR2)3] (5). The further addition of elemental S to 2 results in the formation of [K(18-crown-6)][U(η3-S3)(NR2)3] (3). Complexes 2, 3, and 5 can be reconverted into 1 via the addition of R3P (R = Et, Ph), concomitant with the formation of R3P═E (E = S, Se).

Synthesis, Thermochemistry, Bonding, and 13C NMR Chemical Shift Analysis of a Phosphorano-Stabilized Carbene of Thorium

Co-reporter:Danil E. Smiles, Guang Wu, Peter Hrobárik, and Trevor W. Hayton

Organometallics December 11, 2017 Volume 36(Issue 23) pp:4519-4519

Publication Date(Web):April 21, 2017

DOI:10.1021/acs.organomet.7b00202

Reaction of the Th(IV) metallacycle [Th(CH2SiMe2NSiMe3)(NR2)2] (1; R = SiMe3), with Ph3P═CH2 affords the Th(IV) carbene [Th(CHPPh3)(NR2)3] (2) in good yield. In solution, complex 2 exists in equilibrium with complex 1 and free ylide, Ph3P═CH2. The thermodynamic parameters of this equilibrium were probed using variable-temperature NMR spectroscopy, and these results are compared to those collected for the isostructural U(IV) complex [U(CHPPh3)(NR2)3]. X-ray diffraction studies, together with NMR spectroscopic data and DFT calculations, provide clear evidence for actinide–carbon multiple bonding in the title complex 2, which features the shortest Th–C distance measured thus far. This interaction is best characterized as a strongly polarized σ(Th–C) bond augmented by a three-center two-electron π(Th–C–P)-type interaction. In addition, 13C NMR chemical shifts of carbon atoms bonded to the thorium center were identified as quantitative measures of the An–C bond covalency for a series of structurally related Th carbenes.

Synthesis of a terminal Ce(IV) oxo complex by photolysis of a Ce(III) nitrate complex

Co-reporter:Mikiyas K. Assefa;Guang Wu

Chemical Science (2010-Present) 2017 vol. 8(Issue 11) pp:7873-7878

Publication Date(Web):2017/10/23

DOI:10.1039/C7SC03715E

Reaction of [Ce(NR2)3] (R = SiMe3) with LiNO3 in THF, in the presence of 2,2,2-cryptand, results in the formation of the Ce(III) “ate” complex, [Li(2,2,2-cryptand)][Ce(κ2-O2NO)(NR2)3] (1) in 38% yield. Photolysis of 1 at 380 nm affords [Li(2,2,2-cryptand)][Ce(O)(NR2)3] (2), in 33% isolated yield after reaction work-up. Complex 2 is the first reported example of a Ce(IV) oxo complex where the oxo ligand is not supported by hydrogen bonding or alkali metal coordination. Also formed during photolysis are [Li(2,2,2-cryptand)]2[(μ3-O){Ce(μ-O)(NR2)2}3] (3) and [Li(2,2,2-cryptand)][Ce(OSiMe3)(NR2)3] (4). Their identities were confirmed by X-ray crystallography. Complex 4 can also be prepared via reaction of [Ce(NR2)3] with LiOSiMe3 in THF, in the presence of 2,2,2-cryptand. When synthesized in this fashion, 4 can be isolated in 47% yield. To rationalize the presence of 2, 3, and 4 in the reaction mixture, we propose that photolysis of 1 first generates 2 and NO2, via homolytic cleavage of the N–O bond in its nitrate co-ligand. Complex 2 then undergoes decomposition via two separate routes: (1) ligand scrambling and oligomerization to form 3; and, (2) abstraction of a trimethylsilyl cation to form a transient Ce(IV) silyloxide, [CeIV(OSiMe3)(NR2)3], followed by 1e− reduction to form 4. Alternatively, complex 4 could form directly via ·SiMe3 abstraction by 2.

Formation of a Ce(IV) Oxo Complex via Inner Sphere Nitrate Reduction

Co-reporter:Peter L. Damon, Guang Wu, Nikolas Kaltsoyannis, and Trevor W. Hayton

Journal of the American Chemical Society 2016 Volume 138(Issue 39) pp:12743-12746

Publication Date(Web):September 13, 2016

DOI:10.1021/jacs.6b07932

Reaction of Ce(NO3)3(THF)4 with Li3(THF)3(NN′3) (NN′3 = N(CH2CH2NR)3, R = SitBuMe2) in Et2O, in the presence of 12-crown-4, results in the formation of [Li(12-crown-4)][(NN′3)Ce(O)] (1) in 36% yield. This transformation proceeds via formation of a Ce(III) nitrate intermediate, [Li(12-crown-4)][(NN′3)Ce(κ2-O2NO)] (2), which undergoes inner sphere nitrate reduction. In addition, reaction of 1 with tBuMe2SiCl results in the formation of (NN′3)Ce(OSitBuMe2) (3), confirming the nucleophilic character of its oxo ligand. Natural bond orbital and quantum theory of atoms-in-molecules data reveal the Ce–O interaction in 1 to be significantly covalent, and strikingly similar to analogous U–O bonding.

Reactivity of a Nickel Sulfide with Carbon Monoxide and Nitric Oxide

Co-reporter:Nathaniel J. Hartmann, Guang Wu, and Trevor W. Hayton

Journal of the American Chemical Society 2016 Volume 138(Issue 38) pp:12352-12355

Publication Date(Web):September 8, 2016

DOI:10.1021/jacs.6b08084

The reactivity of the “masked” terminal nickel sulfide complex, [K(18-crown-6)][(LtBu)NiII(S)] (LtBu = {(2,6-iPr2C6H3)NC(tBu)}2CH), with the biologically important small molecules CO and NO, was surveyed. [K(18-crown-6)][(LtBu)NiII(S)] reacts with carbon monoxide (CO) via addition across the Ni–S bond to give a carbonyl sulfide complex, [K(18-crown-6)][(LtBu)NiII(S,C:η2-COS)] (1). Additionally, [K(18-crown-6)][(LtBu)NiII(S)] reacts with nitric oxide (NO) to yield a nickel nitrosyl, [(LtBu)Ni(NO)] (2), and a perthionitrite anion, [K(18-crown-6)][SSNO] (3). The isolation of 3 from this reaction confirms, for the first time, that transition metal sulfides can react with NO to form the biologically important [SSNO]− anion.

Ligand-Exchange-Induced Growth of an Atomically Precise Cu29 Nanocluster from a Smaller Cluster

Co-reporter:Thuy-Ai D. Nguyen, Zachary R. Jones, Domenick F. Leto, Guang Wu, Susannah L. Scott, and Trevor W. Hayton

Chemistry of Materials 2016 Volume 28(Issue 22) pp:8385

Publication Date(Web):October 23, 2016

DOI:10.1021/acs.chemmater.6b03879

The copper hydride nanocluster (NC) [Cu29Cl4H22(Ph2phen)12]Cl (2; Ph2phen = 4,7-diphenyl-1,10-phenanthroline) was isolated cleanly, and in good yields, by controlled growth from the smaller NC, [Cu25H22(PPh3)12]Cl (1), in the presence of Ph2phen and a chloride source at room temperature. Complex 2 was fully characterized by single-crystal X-ray diffraction, XANES, and XPS, and represents a rare example of an N* = 2 superatom. Its formation from 1 demonstrates that atomically precise copper clusters can be used as templates to generate larger NCs that retain the fundamental electronic and bonding properties of the original cluster. A time-resolved kinetic evaluation of the formation of 2 reveals that the mechanism of cluster growth is initiated by rapid ligand exchange. The slower extrusion of CuCl monomer, its transport, and subsequent capture by intact clusters resemble elementary steps in the reactant-assisted Ostwald ripening of metal nanoparticles.

Synthesis, structure and bonding of hexaphenyl thorium(IV): observation of a non-octahedral structure

Co-reporter:Elizabeth A. Pedrick, Peter Hrobárik, Lani A. Seaman, Guang Wu and Trevor W. Hayton

Chemical Communications 2016 vol. 52(Issue 4) pp:689-692

Publication Date(Web):09 Nov 2015

DOI:10.1039/C5CC08265J

We report herein the synthesis of the first structurally characterized homoleptic actinide aryl complexes, [Li(DME)3]2[Th(C6H5)6] (1) and [Li(THF)(12-crown-4)]2[Th(C6H5)6] (2), which feature an anion possessing a regular octahedral (1) or a severely distorted octahedral (2) geometry. The solid-state structure of 2 suggests the presence of pseudo-agostic ortho C–H⋯Th interactions, which arise from σ(C–H) → Th(5f) donation. The non-octahedral structure is also favoured in solution at low temperatures.

Perturbation of the O–U–O Angle in Uranyl by Coordination to a 12-Membered Macrocycle

Co-reporter:Elizabeth A. Pedrick, Jason W. Schultz, Guang Wu, Liviu M. Mirica, and Trevor W. Hayton

Inorganic Chemistry 2016 Volume 55(Issue 11) pp:5693

Publication Date(Web):May 13, 2016

DOI:10.1021/acs.inorgchem.6b00799

Reaction of [UO2Cl2(THF)2]2 (THF = tetrahydrofuran) with 2 equiv of HN4 (HN4 = 2,11-diaza[3,3](2,6) pyridinophane) or MeN4 (MeN4 = N,N′-dimethyl-2,11-diaza[3,3](2,6) pyridinophane), in MeCN, results in the formation of UO2Cl2(RN4) (R = H; 1; Me, 2), which were isolated as yellow-orange solids in good yields. Similarly, reaction of UO2(OTf)2(THF)3 with HN4 in MeCN results in the formation of UO2(OTf)2(HN4) (3), as an orange powder in 76% yield. Finally, reaction of UO2(OTf)2(THF)3 with MeN4 in THF results in the formation of [UO2(OTf)(THF)(HN4)][OTf] (4), as an orange powder in 73% yield. Complexes 1–4 were fully characterized, including characterization by X-ray crystallography. These complexes exhibit the smallest O–U–O bond angles measured to date, ranging from 168.2(3)° (for 2) to 161.7(5)° (for 4), a consequence of an unfavorable steric interaction between the oxo ligands and the macrocycle backbone. A Raman spectroscopic study of 1–4 reveals no correlation between O–U–O angle and the U═O νsym mode. However, complexes 1 and 2 do feature lower U═O νsym modes than complexes 3 and 4, which can be rationalized by the stronger donor strength of Cl– versus OTf–. This observation suggests that the identity of the equatorial ligands has a greater effect on the U═O νsym frequency than does a change in O–U–O angle, at least when the changes in the O–U–O angles are small.

Synthesis, Characterization, and Reactivity of the Group 11 Hydrido Clusters [Ag6H4(dppm)4(OAc)2] and [Cu3H(dppm)3(OAc)2]

Co-reporter:Andrew W. Cook, Thuy-Ai D. Nguyen, William R. Buratto, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2016 Volume 55(Issue 23) pp:12435-12440

Publication Date(Web):November 21, 2016

DOI:10.1021/acs.inorgchem.6b02385

The group 11 hydride clusters [Ag6H4(dppm)4(OAc)2] (1) and [Cu3H(dppm)3(OAc)2] (2) (dppm = 1,1-bis(diphenylphosphino)methane) were synthesized in moderate yields from the reaction of M(OAc) (M = Ag, Cu) with Ph2SiH2, in the presence of dppm. Complex 1 is the first structurally characterized homometallic polyhydrido silver cluster to be isolated. Both 1 and 2 catalyze the hydrosilylation of (α,β-unsaturated) ketones. Notably, this represents the first example of hydrosilylation with an authentic silver hydride complex.

Synthesis, Electrochemistry, and Reactivity of the Actinide Trisulfides [K(18-crown-6)][An(η3-S3)(NR2)3] (An = U, Th; R = SiMe3)

Co-reporter:Danil E. Smiles, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2016 Volume 55(Issue 18) pp:9150-9153

Publication Date(Web):September 6, 2016

DOI:10.1021/acs.inorgchem.6b01618

The reaction of [Th(I)(NR2)3] (R = SiMe3) with [K(18-crown-6)]2[S4] results in the formation of [K(18-crown-6)][Th(η3-S3)(NR2)3] (2). Oxidation of 2, or its uranium analogue, [K(18-crown-6)][U(η3-S3)(NR2)3] (1), with AgOTf, in an attempt to generate an [S3]•– complex, results in the formation of [K(18-crown-6)][An(OTf)2(NR2)3] (3, An = U; 4, An = Th) as the only isolable products. These results suggest that the putative [S3]•– ligand is only weakly coordinating and can be easily displaced by nucleophiles.

Synthesis and Reactivity of a U(IV) Dibenzyne Complex

Co-reporter:Elizabeth A. Pedrick, Lani A. Seaman, Joshua C. Scott, Leonel Griego, Guang Wu, and Trevor W. Hayton

Organometallics 2016 Volume 35(Issue 4) pp:494-502

Publication Date(Web):February 4, 2016

DOI:10.1021/acs.organomet.5b00929

Reaction of UCl4 with 6 equiv of 2-Li-C6H4CH2NMe2 affords the U(IV) dibenzyne complex [Li]2[U(2,3-C6H3CH2NMe2)2(2-C6H4CH2NMe2)2] (1), which can be isolated as a dark blue solid in 40% yield. Complex 1 represents a rare example of a structurally characterized dibenzyne complex, and its solid-state metrical parameters suggest that the two benzyne ligands are best described with the dianionic metallacyclopropene resonance form. The reactivity of 1 with a variety of electrophiles and oxidants, including benzophenone, 1-azidoadamantane, and benzonitrile, was also explored. Reaction of 1 with 2 equiv of benzophenone affords the insertion product [Li][U(2-C6H3CH2NMe2-3-COPh2)2(2-C6H4CH2NMe2)] (3) as a red-orange solid in 61% yield, concomitant with formation of 1 equiv of 2-Li-C6H4CH2NMe2. Reaction of 1 with 2 equiv of PhCN also affords an insertion product, [Li][Li(Et2O)][U(2,3-C6H3CH2NMe2)(2-C6H3CH2NMe2-3-C(Ph)═N)(2-C6H4CH2NMe2)2] (4), as a green-brown crystalline solid in 21% yield. In an attempt to oxidize 1 to U(VI), the reaction of 1 with 2 equiv of AdN3, in the presence of 2 equiv of 12-crown-4, was probed. This reaction only yields the U(IV) insertion product [Li(12-crown-4)2][Li][U(2-C6H3CH2NMe2-3-(N-N═N-Ad))2(2-C6H4CH2NMe2)2] (5) as a red crystalline solid in 42% yield. No evidence for the formation of a U(VI) imido complex is observed in the reaction mixture.

A Cu25 Nanocluster with Partial Cu(0) Character

Co-reporter:Thuy-Ai D. Nguyen; Zachary R. Jones; Bryan R. Goldsmith; William R. Buratto; Guang Wu; Susannah L. Scott

Journal of the American Chemical Society 2015 Volume 137(Issue 41) pp:13319-13324

Publication Date(Web):September 30, 2015

DOI:10.1021/jacs.5b07574

Atomically precise copper nanoclusters (NCs) are of immense interest for a variety of applications, but have remained elusive. Herein, we report the isolation of a copper NC, [Cu25H22(PPh3)12]Cl (1), from the reaction of Cu(OAc) and CuCl with Ph2SiH2, in the presence of PPh3. Complex 1 has been fully characterized, including analysis by X-ray crystallography, XANES, and XPS. In the solid state, complex 1 is constructed around a Cu13 centered-icosahedron and formally features partial Cu(0) character. XANES of 1 reveals a Cu K-edge at 8979.6 eV, intermediate between the edge energies of Cu(0) and Cu(I), confirming our oxidation state assignment. This assignment is further corroborated by determination of the Auger parameter for 1, which also falls between those recorded for Cu(0) and Cu(I).

Use of 77Se and 125Te NMR Spectroscopy to Probe Covalency of the Actinide-Chalcogen Bonding in [Th(En){N(SiMe3)2}3]− (E = Se, Te; n = 1, 2) and Their Oxo-Uranium(VI) Congeners

Co-reporter:Danil E. Smiles; Guang Wu; Peter Hrobárik

Journal of the American Chemical Society 2015 Volume 138(Issue 3) pp:814-825

Publication Date(Web):December 14, 2015

DOI:10.1021/jacs.5b07767

Reaction of [Th(I)(NR2)3] (R = SiMe3) (1) with 1 equiv of either [K(18-crown-6)]2[Se4] or [K(18-crown-6)]2[Te2] affords the thorium dichalcogenides, [K(18-crown-6)][Th(η2-E2)(NR2)3] (E = Se, 2; E = Te, 3), respectively. Removal of one chalcogen atom via reaction with Et3P, or Et3P and Hg, affords the monoselenide and monotelluride complexes of thorium, [K(18-crown-6)][Th(E)(NR2)3] (E = Se, 4; E = Te, 5), respectively. Both 4 and 5 were characterized by X-ray crystallography and were found to feature the shortest known Th–Se and Th–Te bond distances. The electronic structure and nature of the actinide-chalcogen bonds were investigated with 77Se and 125Te NMR spectroscopy accompanied by detailed quantum-chemical analysis. We also recorded the 77Se NMR shift for a U(VI) oxo-selenido complex, [U(O)(Se)(NR2)3]− (δ(77Se) = 4905 ppm), which features the highest frequency 77Se NMR shift yet reported, and expands the known 77Se chemical shift range for diamagnetic substances from ∼3300 ppm to almost 6000 ppm. Both 77Se and 125Te NMR chemical shifts of given chalcogenide ligands were identified as quantitative measures of the An–E bond covalency within an isoelectronic series and supported significant 5f-orbital participation in actinide–ligand bonding for uranium(VI) complexes in contrast to those involving thorium(IV). Moreover, X-ray diffraction studies together with NMR spectroscopic data and density functional theory (DFT) calculations provide convincing evidence for the actinide–chalcogen multiple bonding in the title complexes. Larger An–E covalency is observed in the [U(O)(E)(NR2)3]− series, which decreases as the chalcogen atom becomes heavier.

Thorium–ligand multiple bonds via reductive deprotection of a trityl group

Co-reporter:Danil E. Smiles, Guang Wu, Nikolas Kaltsoyannis and Trevor W. Hayton

Chemical Science 2015 vol. 6(Issue 7) pp:3891-3899

Publication Date(Web):30 Apr 2015

DOI:10.1039/C5SC01248A

Reaction of [Th(I)(NR2)3] (R = SiMe3) (2) with KECPh3 (E = O, S) affords the thorium chalcogenates, [Th(ECPh3)(NR2)3] (3, E = O; 4, E = S), in moderate yields. Reductive deprotection of the trityl group from 3 and 4 by reaction with KC8, in the presence of 18-crown-6, affords the thorium oxo complex, [K(18-crown-6)][Th(O)(NR2)3] (6), and the thorium sulphide complex, [K(18-crown-6)][Th(S)(NR2)3] (7), respectively. The natural bond orbital and quantum theory of atoms-in-molecules approaches are employed to explore the metal–ligand bonding in 6 and 7 and their uranium analogues, and in particular the relative roles of the actinide 5f and 6d orbitals.

Oxo Ligand Substitution in a Cationic Uranyl Complex: Synergistic Interaction of an Electrophile and a Reductant

Co-reporter:Elizabeth A. Pedrick; Guang Wu

Inorganic Chemistry 2015 Volume 54(Issue 14) pp:7038-7044

Publication Date(Web):July 2, 2015

DOI:10.1021/acs.inorgchem.5b01077

Reaction of [UVIO2(dppmo)2(OTf)][OTf] (dppmo = Ph2P(O)CH2P(O)Ph2) with 4 equiv of Ph3SiOTf and 2 equiv of Cp2Co generates the U(IV) complex UIV(OTf)4(dppmo)2 (1), as a yellow-green crystalline solid in 83% yield, along with Ph3SiOSiPh3 and [Cp2Co][OTf]. This reaction proceeds via a U(IV) silyloxide intermediate, [UIV(OSiPh3)(dppmo)2(OTf)2][OTf] (2), which we have isolated and structurally characterized. Similarly, reaction of [UVIO2(TPPO)4][OTf]2 (TPPO = Ph3PO) with 6 equiv of Me3SiOTf and 2 equiv of Cp2Co generates the U(IV) complex, [Cp2Co][UIV(OTf)5(TPPO)2] (3), as a yellow-green crystalline solid in 76% yield, concomitant with formation of Me3SiOSiMe3, [Ph3POSiMe3][OTf], and [Cp2Co][OTf]. Complexes 1 and 3 have been fully characterized, including analysis by X-ray crystallography. The conversion of [UVIO2(dppmo)2(OTf)][OTf] and [UVIO2(TPPO)4][OTf]2 to complexes 1 and 3, respectively, represents rare examples of well-defined uranyl oxo ligand substitution.

Understanding the Role of Hyponitrite in Nitric Oxide Reduction

Co-reporter:Ashley M. Wright

Inorganic Chemistry 2015 Volume 54(Issue 19) pp:9330-9341

Publication Date(Web):April 30, 2015

DOI:10.1021/acs.inorgchem.5b00516

Herein, we review the preparation and coordination chemistry of cis and trans isomers of hyponitrite, [N2O2]2–. Hyponitrite is known to bind to metals via a variety of bonding modes. In fact, at least eight different bonding modes have been observed, which is remarkable for such a simple ligand. More importantly, it is apparent that the cis isomer of hyponitrite is more reactive than the trans isomer because the barrier of N2O elimination from cis-hyponitrite is lower than that of trans-hyponitrite. This observation may have important mechanistic implications for both heterogeneous NOx reduction catalysts and NO reductase. However, our understanding of the hyponitrite ligand has been limited by the lack of a general route to this fragment, and most instances of its formation have been serendipitous.

Quantifying the Electron Donor and Acceptor Abilities of the Ketimide Ligands in M(N═CtBu2)4 (M = V, Nb, Ta)

Co-reporter:Peter L. Damon, Cameron J. Liss, Richard A. Lewis, Simona Morochnik, David E. Szpunar, Joshua Telser, and Trevor W. Hayton

Inorganic Chemistry 2015 Volume 54(Issue 20) pp:10081-10095

Publication Date(Web):September 30, 2015

DOI:10.1021/acs.inorgchem.5b02017

Addition of 4 equiv of Li(N═CtBu2) to VCl3 in THF, followed by addition of 0.5 equiv of I2, generates the homoleptic V(IV) ketimide complex, V(N═CtBu2)4 (1), in 42% yield. Similarly, reaction of 4 equiv of Li(N═CtBu2) with NbCl4(THF)2 in THF affords the homoleptic Nb(IV) ketimide complex, Nb(N═CtBu2)4 (2), in 55% yield. Seeking to extend the series to the tantalum congener, a new Ta(IV) starting material, TaCl4(TMEDA) (3), was prepared via reduction of TaCl5 with Et3SiH, followed by addition of TMEDA. Reaction of 3 with 4 equiv of Li(N═CtBu2) in THF results in the isolation of a Ta(V) ketimide complex, Ta(Cl)(N═CtBu2)4 (5), which can be isolated in 32% yield. Reaction of 5 with Tl(OTf) yields Ta(OTf)(N═CtBu2)4 (6) in 44% yield. Subsequent reduction of 6 with Cp*2Co in toluene generates the homoleptic Ta(IV) congener Ta(N═CtBu2)4 (7), although the yields are poor. All three homoleptic group 5 ketimide complexes exhibit squashed tetrahedral geometries in the solid state, as determined by X-ray crystallography. This geometry leads to a dx2–y21 (2B1 in D2d) ground state, as supported by DFT calculations. EPR spectroscopic analysis of 1 and 2, performed at X- and Q-band frequencies (∼9 and 35 GHz, respectively), further supports the 2B1 ground-state assignment, whereas comparison of 1, 2, and 7 with related group 5 tetra(aryl), tetra(amido), and tetra(alkoxo) complexes shows a higher M–L covalency in the ketimide–metal interaction. In addition, a ligand field analysis of 1 and 2 demonstrates that the ketimide ligand is both a strong π-donor and strong π-acceptor, an unusual combination found in very few organometallic ligands.

Reactivity of [U(CH2SiMe2NSiMe3)(NR2)2] (R = SiMe3) with elemental chalcogens: towards a better understanding of chalcogen atom transfer in the actinides

Co-reporter:Danil E. Smiles, Guang Wu and Trevor W. Hayton

New Journal of Chemistry 2015 vol. 39(Issue 10) pp:7563-7566

Publication Date(Web):19 May 2015

DOI:10.1039/C5NJ00739A

The reaction of the U(IV) metallacycle, [U(CH2SiMe2NSiMe3)(NR2)2] (R = SiMe3) with the elemental chalcogens, E (E = S, Se, Te) affords the insertion products, [U(ECH2SiMe2NSiMe3)(NR2)2], in good yields. All three can transfer the chalcogen atom to [U(NR2)3] to give the bridged mono-chalcogenides [U(NR2)3](μ-E) (E = S, Se, Te) and regenerate [U(CH2SiMe2NSiMe3)(NR2)2]. Additionally, the reaction of [U(Cl)(NR2)3] with 2 equiv. of KSCPh3 affords the di-sulfide, [K(Et2O)2][U(S2)(NR2)3].

Synthesis of a Masked Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

Co-reporter:Nathaniel J. Hartmann;Dr. Guang Wu ;Dr. Trevor W. Hayton

Angewandte Chemie International Edition 2015 Volume 54( Issue 49) pp:14956-14959

Publication Date(Web):

DOI:10.1002/anie.201508232

Abstract

The addition of 1 equiv of KSCPh₃ to [L^RNiCl] (L^R={(2,6-iPr₂C₆H₃)NC(R)}₂CH; R=Me, tBu) in C₆H₆ results in the formation of [L^RNi(SCPh₃)] (1: R=Me; 2: R=tBu) in good yields. Subsequent reduction of 1 and 2 with 2 equiv of KC₈ in cold (−25 °C) Et₂O in the presence of 2 equiv of 18-crown-6 results in the formation of “masked” terminal Ni^II sulfides, [K(18-crown-6)][L^RNi(S)] (3: R=Me; 4: R=tBu), also in good yields. An X-ray crystallographic analysis of these complexes suggests that they feature partial multiple-bond character in their NiS linkages. Addition of N₂O to a toluene solution of 4 provides [K(18-crown-6)][L^tBuNi(SNNO)], which features the first example of a thiohyponitrite (κ²-[SNNO]²⁻) ligand.

A Copper(I)Arene Complex With an Unsupported 6 Interaction

Co-reporter:Dr. Ashley M. Wright;Dr. Benjamin J. Irving;Dr. Guang Wu;Dr. Anthony J. H. M. Meijer;Dr. Trevor W. Hayton

Angewandte Chemie 2015 Volume 127( Issue 10) pp:3131-3134

Publication Date(Web):

DOI:10.1002/ange.201410948

Abstract

Addition of PR₃ (R=Ph or OPh) to [Cu(η²-Me₆C₆)₂][PF₆] results in the formation of [(η⁶-Me₆C₆)Cu(PR₃)][PF₆], the first copper–arene complexes to feature an unsupported η⁶ arene interaction. A DFT analysis reveals that the preference for the η⁶ binding mode is enforced by the steric clash between the methyl groups of the arene ligand and the phenyl rings of the phosphine co-ligand.

Synthesis of a Masked Terminal Nickel(II) Sulfide by Reductive Deprotection and its Reaction with Nitrous Oxide

Co-reporter:Nathaniel J. Hartmann;Dr. Guang Wu ;Dr. Trevor W. Hayton

Angewandte Chemie 2015 Volume 127( Issue 49) pp:15169-15172

Publication Date(Web):

DOI:10.1002/ange.201508232

Abstract

A Copper(I)Arene Complex With an Unsupported 6 Interaction

Co-reporter:Dr. Ashley M. Wright;Dr. Benjamin J. Irving;Dr. Guang Wu;Dr. Anthony J. H. M. Meijer;Dr. Trevor W. Hayton

Angewandte Chemie International Edition 2015 Volume 54( Issue 10) pp:3088-3091

Publication Date(Web):

DOI:10.1002/anie.201410948

Abstract

Synthesis and Characterization of a Cu14 Hydride Cluster Supported by Neutral Donor Ligands

Co-reporter:Thuy-Ai D. Nguyen;Bryan R. Goldsmith;Homaira T. Zaman;Dr. Guang Wu;Dr. Baron Peters;Dr. Trevor W. Hayton

Chemistry - A European Journal 2015 Volume 21( Issue 14) pp:5341-5344

Publication Date(Web):

DOI:10.1002/chem.201500422

Abstract

The copper hydride clusters [Cu₁₄H₁₂(phen)₆(PPh₃)₄][X]₂ (X=Cl or OTf; OTf=trifluoromethanesulfonate, phen=1,10-phenanthroline) are obtained in good yields by the reaction of [(Ph₃P)CuH]₆ with phen, in the presence of a halide or pseudohalide source. The complex [Cu₁₄H₁₂(phen)₆(PPh₃)₄][Cl]₂ reacts with CO₂ in CH₂Cl₂, in the presence of excess Ph₃P, to form the formate complex [(Ph₃P)₂Cu(κ²-O₂CH)], along with [(phen)(Ph₃P)CuCl].

Reductive silylation of a uranyl dibenzoylmethanate complex: an example of controlled uranyl oxo ligand cleavage

Co-reporter:E. A. Pedrick, G. Wu, N. Kaltsoyannis and T. W. Hayton

Chemical Science 2014 vol. 5(Issue 8) pp:3204-3213

Publication Date(Web):23 May 2014

DOI:10.1039/C4SC00996G

Reaction of UO2(dbm)2(THF) (dbm = OC(Ph)CHC(Ph)O) with 1 equiv. of R3SiH (R = Ph, Et), in the presence of B(C6F5)3, results in the formation of U(OB{C6F5}3)(OSiR3)(dbm)2(THF) (R = Ph, 1; Et, 2), which were isolated as red-orange crystalline solids in good yields. Interestingly, the addition of 1 equiv. of H(dbm) to 2 results in protonation of the –OSiEt3 ligand and formation of U(OB{C6F5}3)(dbm)3 (4) in 33% yield, along with formation of HOSiEt3. Furthermore, addition of HOSiEt3 and 1 equiv. of THF to 4, results in the formation 2, revealing that this process is reversible. The two-step conversion of UO2(dbm)2(THF) to 4 represents a rare example of controlled uranyl oxo ligand cleavage at ambient temperature and pressure. Comparison of diffraction and density functional theory data for 4 suggests the presence of the inverse trans influence, with a very shallow potential energy well for distortion along the trans U–O bond.

Reductive Silylation of the Uranyl Ion with Ph3SiOTf

Co-reporter:Elizabeth A. Pedrick, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2014 Volume 53(Issue 23) pp:12237-12239

Publication Date(Web):November 11, 2014

DOI:10.1021/ic502267t

The reaction of 2 equiv of Ph3SiOTf with UO2(dbm)2(THF) (dbm = OC(Ph)CHC(Ph)O) and UO2(Aracnac)2 (Aracnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-tBu2C6H3) results in the formation of U(OSiPh3)2(dbm)2(OTf) (1) and [U(OSiPh3)2(Aracnac)2][OTf] (2), respectively, in good yield.

Synthesis of Terminal Monochalcogenide and Dichalcogenide Complexes of Uranium Using Polychalcogenides, [En]2– (E = Te, n = 2; E = Se, n = 4), as Chalcogen Atom Transfer Reagents

Co-reporter:Danil E. Smiles, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2014 Volume 53(Issue 19) pp:10240-10247

Publication Date(Web):September 9, 2014

DOI:10.1021/ic501267f

Reaction of KH with elemental tellurium, in the presence of 18-crown-6, results in the formation of the ditelluride, [K(18-crown-6)]2[Te2] (1), in good yield. Similarly, reaction of KH with elemental selenium, in the presence of 18-crown-6, results in the formation of [K(18-crown-6)]2[Se4] (4). Both 1 and 4 are capable of chalcogen atom transfer to U(III). For example, addition of 0.5 equiv or 1 equiv of [K(18-crown-6)]2[Te2] (1) to [U(NR2)3] (R = SiMe3) or [U(I)(NR2)3], respectively, results in the formation of the new U(IV) tellurides, [K(18-crown-6)][U(Te)(NR2)3] (2), and [K(18-crown-6)][U(η2-Te2)(NR2)3] (3), in moderate yields, while addition of 0.5 equiv of [K(18-crown-6)]2[Se4] (4) to [U(NR2)3] results in the formation of the U(IV) diselenide, [K(18-crown-6)][U(η2-Se2)(NR2)3] (5). Interestingly, 5 can be converted into the monoselenide [K(18-crown-6)][U(Se)(NR2)3] (6) via reaction with Ph3P.

Mechanistic Insights into the Formation of N2O by a Nickel Nitrosyl Complex

Co-reporter:Ashley M. Wright, Homaira T. Zaman, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2014 Volume 53(Issue 6) pp:3108-3116

Publication Date(Web):March 5, 2014

DOI:10.1021/ic403038e

Reaction of [Ni(NO)(bipy)(Me2phen)][PF6] with 1 equiv of nitric oxide (NO) in CH2Cl2 results in the formation of N2O and [{(Me2phen)Ni(NO)}2(μ–η1-N:η1-O)-NO2)][PF6] (3), along with the known complex, [Ni(bipy)3][PF6]2 (4). The isolation of complex 3, which contains a nitrite ligand, demonstrates that the reaction of [Ni(NO)(bipy)(Me2phen)][PF6] with exogenous NO results in NO disproportionation and not NO reduction. Complex 3 could also be accessed by reaction of [Ni(NO)(Me2phen)][PF6] (5) with (Me2phen)Ni(NO)(NO2) (7) in good yield. Complexes 3, 5, and 7 were fully characterized, including analysis by X-ray crystallography in the case of 3 and 7. Furthermore, addition of 0.5 equiv of bipy to [Ni(NO)(bipy)][PF6] results in formation of the hyponitrite complex, [{(bipy)Ni(κ2-O2N2)}η1:η1-N,N-{Ni(NO)(bipy)}2][PF6]2 (9), in modest yield. Importantly, the hyponitrite ligand in 9 is thought to form via coupling of two NO– ligands and not by coupling of a nucleophilic nitrosyl ligand (NO–) with an electrophilic nitrosyl ligand (NO+). X-ray crystallography reveals that complex 9 features a new binding mode of the cis-hyponitrite ligand.

Oxidation of Alcohols and Activated Alkanes with Lewis Acid-Activated TEMPO

Co-reporter:Thuy-Ai D. Nguyen, Ashley M. Wright, Joshua S. Page, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2014 Volume 53(Issue 21) pp:11377-11387

Publication Date(Web):October 16, 2014

DOI:10.1021/ic5018888

The reactivity of MCl3(η1-TEMPO) (M = Fe, 1; Al, 2; TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) with a variety of alcohols, including 3,4-dimethoxybenzyl alcohol, 1-phenyl-2-phenoxyethanol, and 1,2-diphenyl-2-methoxyethanol, was investigated using NMR spectroscopy and mass spectrometry. Complex 1 was effective in cleanly converting these substrates to the corresponding aldehyde or ketone. Complex 2 was also able to oxidize these substrates; however, in a few instances the products of overoxidation were also observed. Oxidation of activated alkanes, such as xanthene, by 1 or 2 suggests that the reactions proceed via an initial 1-electron concerted proton–electron transfer (CPET) event. Finally, reaction of TEMPO with FeBr3 in Et2O results in the formation of a mixture of FeBr3(η1-TEMPOH) (23) and [FeBr2(η1-TEMPOH)]2(μ-O) (24), via oxidation of the solvent, Et2O.

Quantifying the σ and π Interactions between U(V) f Orbitals and Halide, Alkyl, Alkoxide, Amide and Ketimide Ligands

Co-reporter:Wayne W. Lukens ; Norman M. Edelstein ; Nicola Magnani ; Trevor W. Hayton ; Skye Fortier ;Lani A. Seaman

Journal of the American Chemical Society 2013 Volume 135(Issue 29) pp:10742-10754

Publication Date(Web):June 19, 2013

DOI:10.1021/ja403815h

f Orbital bonding in actinide and lanthanide complexes is critical to their behavior in a variety of areas from separations to magnetic properties. Octahedral f1 hexahalide complexes have been extensively used to study f orbital bonding due to their simple electronic structure and extensive spectroscopic characterization. The recent expansion of this family to include alkyl, alkoxide, amide, and ketimide ligands presents the opportunity to extend this study to a wider variety of ligands. To better understand f orbital bonding in these complexes, the existing molecular orbital (MO) model was refined to include the effect of covalency on spin orbit coupling in addition to its effect on orbital angular momentum (orbital reduction). The new MO model as well as the existing MO model and the crystal field (CF) model were applied to the octahedral f1 complexes to determine the covalency and strengths of the σ and π bonds formed by the f orbitals. When covalency is significant, MO models more precisely determined the strengths of the bonds derived from the f orbitals; however, when covalency was small, the CF model was better than either MO model. The covalency determined using the new MO model is in better agreement with both experiment and theory than that predicted by the existing MO model. The results emphasize the role played by the orbital energy in determining the strength and covalency of bonds formed by the f orbitals.

Synthesis of Uranium–Ligand Multiple Bonds by Cleavage of a Trityl Protecting Group

Co-reporter:Danil E. Smiles ; Guang Wu

Journal of the American Chemical Society 2013 Volume 136(Issue 1) pp:96-99

Publication Date(Web):December 18, 2013

DOI:10.1021/ja411423a

Addition of KSCPh3 to [U(NR2)3] (R = SiMe3) in tetrahydrofuran, followed by addition of 18-crown-6, results in formation of the U(IV) sulfide, [K(18-crown-6)][U(S)(NR2)3] (1) and Gomberg’s dimer. Similarly, addition of KOCPh3 to [U(NR2)3] in tetrahydrofuran, followed by addition of 18-crown-6, results in formation of the U(IV) oxide, [K(18-crown-6)][U(O)(NR2)3] (3). Also observed in this transformation are the triphenylmethyl anion, [K(18-crown-6)(THF)2][CPh3] (5), and the U(IV) alkoxide, [U(OCPh3)(NR2)3] (4).

Synthesis and Spectroscopic and Computational Characterization of the Chalcogenido-Substituted Analogues of the Uranyl Ion, [OUE]2+ (E = S, Se)

Co-reporter:Jessie L. Brown ; Skye Fortier ; Guang Wu ; Nikolas Kaltsoyannis

Journal of the American Chemical Society 2013 Volume 135(Issue 14) pp:5352-5355

Publication Date(Web):March 22, 2013

DOI:10.1021/ja402068j

Addition of E (E = 0.125S8, Se) to [Cp*2Co][U(O)(NR2)3] (R = SiMe3) in THF results in the isolation of the chalcogen-substituted uranyl analogues [Cp*2Co][U(O)(E)(NR2)3] [E = S (1), Se (2)] in good yields. Similarly, addition of 1 equiv of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to [Cp*2Co][U(O)(NR2)3] affords the uranyl complex [Cp*2Co][UO2(NR2)3] (3). All of the complexes were fully characterized, including analysis by X-ray crystallography. They were also analyzed by density functional theory calculations to probe the changes in the U–E bond as group 16 is descended.

Synthesis of a cobalt(IV) ketimide with a squashed tetrahedral geometry

Co-reporter:Richard A. Lewis, Stephen P. George, Alon Chapovetsky, Guang Wu, Joshua S. Figueroa and Trevor W. Hayton

Chemical Communications 2013 vol. 49(Issue 28) pp:2888-2890

Publication Date(Web):22 Feb 2013

DOI:10.1039/C3CC40461G

Oxidation of [Li(THF)]2[Co(NCtBu2)4] with 1 equiv. of I2 generates Co(NCtBu2)4 in 85% yield. In the solid-state, this complex exhibits a squashed tetrahedral structure about the Co center. DFT calculations reveal this geometry arises, in part, to maximize ketimide-to-cobalt π-donation.

Recent developments in actinide–ligand multiple bonding

Co-reporter:Trevor W. Hayton

Chemical Communications 2013 vol. 49(Issue 29) pp:2956-2973

Publication Date(Web):31 Jan 2013

DOI:10.1039/C3CC39053E

In the last few years, considerable progress has been made in the synthesis and characterization of complexes containing actinide–ligand multiple bonds, especially in regards to isolation of terminal oxo, nitrido and carbene-containing complexes. This review summarizes the synthesis, structure, and reactivity of these complexes, from 2010 until present. These complexes are of interest for a variety of reasons, including their potential use in novel catalytic transformations and their ability to engage the 5f orbitals in metal–ligand bonding. Of particular note are the recent syntheses of the first isolable complex containing the nitride-substituted uranyl ion, [NUO]+, and the first report of an isolable terminal uranium nitride. Considerable progress has also been made toward the syntheses of actinide carbenes and thorium complexes containing metal–ligand multiple bonds.

Reactivity and Mössbauer Spectroscopic Characterization of an Fe(IV) Ketimide Complex and Reinvestigation of an Fe(IV) Norbornyl Complex

Co-reporter:Richard A. Lewis, Danil E. Smiles, Jonathan M. Darmon, S. Chantal E. Stieber, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2013 Volume 52(Issue 14) pp:8218-8227

Publication Date(Web):June 21, 2013

DOI:10.1021/ic401096p

Thermolysis of Fe(N═CtBu2)4 (1) for 8 h at 50 °C generates the mixed valent Fe(III)/Fe(II) bimetallic complex Fe2(N═CtBu2)5 (2) in moderate yield. Also formed in this reaction are tert-butyl cyanide, isobutane, and isobutylene, the products of ketimide oxidation by the Fe4+ center. Reaction of 1 with 1 equiv of acetylacetone affords the Fe(III) complex, Fe(N═CtBu2)2(acac) (3), concomitant with formation of bis(tert-butyl)ketimine, tert-butyl cyanide, isobutane, and isobutylene. In addition, the Mössbauer spectra of 1 and its lower-valent analogues [Li(12-crown-4)2][Fe(N═CtBu2)4] (5) and [Li(THF)]2[Fe(N═CtBu2)4] (6) were recorded. We also revisited the chemistry of Fe(1-norbornyl)4 (4) to elucidate its solid-state molecular structure and determine its Mössbauer spectrum, for comparison with that recorded for 1.

In Pursuit of Homoleptic Actinide Alkyl Complexes

Co-reporter:Lani A. Seaman, Justin R. Walensky, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2013 Volume 52(Issue 7) pp:3556-3564

Publication Date(Web):June 20, 2012

DOI:10.1021/ic300867m

This Forum Article describes the pursuit of isolable homoleptic actinide alkyl complexes, starting with the pioneering work of Gilman during the Manhattan project. The initial reports in this area suggested that homoleptic uranium alkyls were too unstable to be isolated, but Wilkinson demonstrated that tractable uranium alkyls could be generated by purposeful “ate” complex formation, which serves to saturate the uranium coordination sphere and provide the complexes with greater kinetic stability. More recently, we reported the solid-state molecular structures of several homoleptic uranium alkyl complexes, including [Li(THF)4][U(CH2tBu)5], [Li(TMEDA)]2[UMe6], [K(THF)]3[K(THF)2][U(CH2Ph)6]2, and [Li(THF)4][U(CH2SiMe3)6], by employing Wilkinson’s strategy. Herein, we describe our attempts to extend this chemistry to thorium. The treatment of ThCl4(DME)2 with 5 equiv of LiCH2tBu or LiCH2SiMe3 at −25 °C in THF affords [Th(CH2tBu)5] (1) and [Li(DME)2][Th(CH2SiMe3)5 (2), respectively, in moderate yields. Similarly, the treatment of ThCl4(DME)2 with 6 equiv of K(CH2Ph) produces [K(THF)]2[Th(CH2Ph)6] (3), in good yield. Complexes 1–3 have been fully characterized, while the structures of 1 and 3 were confirmed by X-ray crystallography. Additionally, the electronic properties of 1 and 3 were explored by density functional theory.

Nitric Oxide Release from a Nickel Nitrosyl Complex Induced by One-Electron Oxidation

Co-reporter:Ashley M. Wright, Homaira T. Zaman, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2013 Volume 52(Issue 6) pp:3207-3216

Publication Date(Web):February 22, 2013

DOI:10.1021/ic302697v

Reaction of [Ni(NO)(bipy)][PF6] (2) with AgPF6 or [NO][PF6] in MeCN results in formation of [Ni(bipy)x(MeCN)y]2+ and release of NO gas in moderate yields. In contrast, the addition of the inner sphere oxidant Ph2S2 to 2 does not result in denitrosylation. Instead, the diphenyldisulfide adduct [{(bipy)(NO)Ni}2(μ-S2Ph2)][PF6]2 (3) is formed in good yield. However, oxidation of 2 with 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) does results in cleavage of the Ni–NO bond and generation of NO. The metal-containing product, [(bipy)Ni(η2-TEMPO)][PF6] (4), can be isolated as an orange-brown solid in excellent yields. In the solid state, complex 4 contains a side-on bound TEMPO– ligand, which is characterized by a long N–O bond length [1.383(2) Å]. The contrasting reactivity of Ph2S2 and TEMPO likely relates to their different redox potentials, as Ph2S2 is a relatively weak oxidant. Finally, the addition of pyridine-N-oxide to 2 results in the formation of the adduct, [(bipy)Ni(NO)(ONC5H5)][PF6] (5). No evidence of NO release is observed in this reaction, probably because of the low one-electron (1e–) reduction potential of pyridine-N-oxide.

Divergent Reactivity of TEMPO with MBr3 (M = B, Al)

Co-reporter:Ashley M. Wright;Joshua S. Page;Jeremiah J. Scepaniak;Guang Wu

European Journal of Inorganic Chemistry 2013 Volume 2013( Issue 22-23) pp:3817-3820

Publication Date(Web):

DOI:10.1002/ejic.201300163

Abstract

Addition of TEMPO (TEMPO = 2,2,6,6-tetramethylpiperidine-N-oxyl) to a toluene slurry of AlBr₃ results in rapid formation of AlBr₃(η¹-TEMPO) (1), which can be isolated in 65 % yield. In contrast, addition of TEMPO to a hexanes solution of BBr₃ results in formation of [TEMPO][BBr₄] (2) and (TEMPO)₂BBr (3), the products of TEMPO disproportionation. Complexes 1–3 have been fully characterized, including analysis by X-ray crystallography. The divergent reactivity is likely dictated by the Lewis acidity of the group 13 halide, and in the case of the stronger Lewis acid BBr₃, coordination of TEMPO to the boron center generates an adduct that is capable of oxidizing free TEMPO.

A Rare Uranyl(VI)Alkyl Ate Complex [Li(DME)1.5]2[UO2(CH2SiMe3)4] and Its Comparison with a Homoleptic Uranium(VI)Hexaalkyl

Co-reporter:Dr. Lani A. Seaman;Dr. Peter Hrobárik;Michael F. Schettini;Dr. Skye Fortier;Dr. Martin Kaupp;Dr. Trevor W. Hayton

Angewandte Chemie International Edition 2013 Volume 52( Issue 11) pp:3259-3263

Publication Date(Web):

DOI:10.1002/anie.201209611

Inside Cover: A Rare Uranyl(VI)Alkyl Ate Complex [Li(DME)1.5]2[UO2(CH2SiMe3)4] and Its Comparison with a Homoleptic Uranium(VI)Hexaalkyl (Angew. Chem. Int. Ed. 11/2013)

Co-reporter:Dr. Lani A. Seaman;Dr. Peter Hrobárik;Michael F. Schettini;Dr. Skye Fortier;Dr. Martin Kaupp;Dr. Trevor W. Hayton

Angewandte Chemie International Edition 2013 Volume 52( Issue 11) pp:

Publication Date(Web):

DOI:10.1002/anie.201301041

Chalcogen Atom Transfer to Uranium(III): Synthesis and Characterization of [(R2N)3U]2(μ-E) and [(R2N)3U]2(μ-η2:η2-S2) (R = SiMe3; E = S, Se, Te)

Co-reporter:Jessie L. Brown, Guang Wu, and Trevor W. Hayton

Organometallics 2013 Volume 32(Issue 5) pp:1193-1198

Publication Date(Web):November 30, 2012

DOI:10.1021/om301004q

Addition of 0.0625 equiv of S8 to U(NR2)3 (R = SiMe3) in Et2O generates [(R2N)3U]2(μ-S) (1), which can be isolated in moderate yield by crystallization from cold Et2O. Interestingly, if the U(NR2)3 starting material is contaminated with the U(IV) metallacycle U(CH2SiMe2NSiMe3)(NR2)2, then a second product is also formed in the reaction with S8, namely, [(R2N)3U]2(μ-η2:η2-S2) (2). This species can be separated from 1, in low yield, by virtue of its insolubility in Et2O. Finally, addition of 0.5 equiv of E (E = Se, Te) to U(NR2)3 (R = SiMe3) results in the formation of [(R2N)3U]2(μ-E) (E = Se (3), Te (4)) in moderate yields. Complexes 1–4 were fully characterized, including analysis by X-ray crystallography.

Probing the 5f Orbital Contribution to the Bonding in a U(V) Ketimide Complex

Co-reporter:Lani A. Seaman ; Guang Wu ; Norman Edelstein ; Wayne W. Lukens ; Nicola Magnani

Journal of the American Chemical Society 2012 Volume 134(Issue 10) pp:4931-4940

Publication Date(Web):February 10, 2012

DOI:10.1021/ja211875s

Reaction of UCl4 with 5 equiv of Li(N═CtBuPh) generates the homoleptic U(IV) ketimide complex [Li(THF)2][U(N═CtBuPh)5] (1) in 71% yield. Similarly, reaction of UCl4 with 5 equiv of Li(N═CtBu2) affords [Li(THF)][U(N═CtBu2)5] (2) in 67% yield. Oxidation of 2 with 0.5 equiv of I2 results in the formation of the neutral U(V) complex U(N═CtBu2)5 (3). In contrast, oxidation of 1 with 0.5 equiv of I2, followed by addition of 1 equiv of Li(N═CtBuPh), generates the octahedral U(V) ketimide complex [Li][U(N═CtBuPh)6] (4) in 68% yield. Complex 4 can be further oxidized to the U(VI) ketimide complex U(N═CtBuPh)6 (5). Complexes 1–5 were characterized by X-ray crystallography, while SQUID magnetometry, EPR spectroscopy, and UV–vis–NIR spectroscopy measurements were also preformed on complex 4. Using this data, the crystal field splitting parameters of the f orbitals were determined, allowing us to estimate the amount of f orbital participation in the bonding of 4.

A Complete Family of Terminal Uranium Chalcogenides, [U(E)(N{SiMe3}2)3]− (E = O, S, Se, Te)

Co-reporter:Jessie L. Brown ; Skye Fortier ; Richard A. Lewis ; Guang Wu

Journal of the American Chemical Society 2012 Volume 134(Issue 37) pp:15468-15475

Publication Date(Web):August 25, 2012

DOI:10.1021/ja305712m

Addition of 1 equiv of E (E = 0.125 S8, Se, Te) to U(H2C═PPh3)(NR2)3 (R = SiMe3) (1) in Et2O results in generation of the terminal chalcogenide complexes, [Ph3PCH3][U(E)(NR2)3] (E = S, 2; Se, 3; Te, 4; R = SiMe3), in modest yield. Complexes 2–4 represent extremely rare examples of terminal uranium monochalcogenides. Synthesis of the oxo analogue, [Cp*2Co][U(O)(NR2)3] (5), was achieved by reduction of [U(O)(NR2)3] with Cp*2Co. All complexes were fully characterized, including analysis by X-ray crystallography. In the solid state, complexes 2–5 feature short U–E bond lengths, suggestive of actinide–ligand multiple bonding.

Formation of N2O from a Nickel Nitrosyl: Isolation of the cis-[N2O2]2– Intermediate

Co-reporter:Ashley M. Wright ; Guang Wu

Journal of the American Chemical Society 2012 Volume 134(Issue 24) pp:9930-9933

Publication Date(Web):June 7, 2012

DOI:10.1021/ja304204q

Addition of 2,2′-bipyridine (bipy) to [Ni(NO)(bipy)][PF6] (1) results in formation of a rare five-coordinate nickel nitrosyl [Ni(NO)(bipy)2][PF6] (2). This complex exhibits a bent NO– ligand in the solid state. On standing in acetonitrile, 2 furnishes the NO coupled product, [Ni(κ2-O2N2)(bipy)] (8) in moderate yield. Subsequent addition of 2 equiv of acetylacetone (H(acac)) to 8 results in formation of [Ni(acac)2(bipy)], N2O, and H2O. Preliminary mechanistic studies suggest that the N–N bond is formed via a bimetallic coupling reaction of two NO– ligands.

Tuning the Reactivity of TEMPO by Coordination to a Lewis Acid: Isolation and Reactivity of MCl3(η1-TEMPO) (M = Fe, Al)

Co-reporter:Jeremiah J. Scepaniak ; Ashley M. Wright ; Richard A. Lewis ; Guang Wu

Journal of the American Chemical Society 2012 Volume 134(Issue 47) pp:19350-19353

Publication Date(Web):November 7, 2012

DOI:10.1021/ja309499h

Addition of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) to MCl3 (M = Fe, Al) results in the formation of MCl3(η1-TEMPO) [M = Fe (1), Al (2)]. Both 1 and 2 oxidize alcohols to generate ketones or aldehydes along with the reduced complexes MCl3(η1-TEMPOH) [M = Fe (3), Al (4)]. Complexes 1–4 were fully characterized, including analysis by X-ray crystallography. Additionally, control experiments indicated that neither MCl3 (M = Al, Fe) nor TEMPO are capable of effecting the oxidation of alcohols independently.

Synthesis and reactivity of a uranyl-imidazolyl complex

Co-reporter:Michael F. Schettini, Guang Wu and Trevor W. Hayton

Chemical Communications 2012 vol. 48(Issue 10) pp:1484-1486

Publication Date(Web):22 Aug 2011

DOI:10.1039/C1CC13192C

Treatment of [UO2(Ar2nacnac)Cl]2 with 4 equiv. of Li(C4H5N2) results in the formation of a rare uranyl organometallic complex [Li(MeIm)][UO(μ-O)(Ar2nacnac)(μ-C,N-C4H5N2)2] (2), in moderate yield. Reaction of 2 with 1 equiv. of MCl2 (M = Fe, Co) yields the bimetallic complexes [MCl(MeIm)][UO2(Ar2nacnac)(μ-N,C-C4H5N2)2] (M = Fe, 3; M = Co, 4).

Bonding Trends Traversing the Tetravalent Actinide Series: Synthesis, Structural, and Computational Analysis of AnIV(Aracnac)4 Complexes (An = Th, U, Np, Pu; Aracnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-tBu2C6H3)

Co-reporter:David D. Schnaars ; Andrew J. Gaunt ; Trevor W. Hayton ; Matthew B. Jones ; Ian Kirker ; Nikolas Kaltsoyannis ; Iain May ; Sean D. Reilly ; Brian L. Scott ;Guang Wu

Inorganic Chemistry 2012 Volume 51(Issue 15) pp:8557-8566

Publication Date(Web):July 26, 2012

DOI:10.1021/ic301109f

A series of tetravalent An(IV) complexes with a bis-phenyl β-ketoiminate N,O donor ligand has been synthesized with the aim of identifying bonding trends and changes across the actinide series. The neutral molecules are homoleptic with the formula An(Aracnac)4 (An = Th (1), U (2), Np (3), Pu (4); Aracnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-tBu2C6H3) and were synthesized through salt metathesis reactions with actinide chloride precursors. NMR and electronic absorption spectroscopy confirm the purity of all four new compounds and demonstrate stability in both solution and the solid state. The Th, U, and Pu complexes were structurally elucidated by single-crystal X-ray diffraction and shown to be isostructural in space group C2/c. Analysis of the bond lengths reveals shortening of the An–O and An–N distances arising from the actinide contraction upon moving from 1 to 2. The shortening is more pronounced upon moving from 2 to 4, and the steric constraints of the tetrakis complexes appear to prevent the enhanced U–O versus Pu–O orbital interactions previously observed in the comparison of UI2(Aracnac)2 and PuI2(Aracnac)2 bis-complexes. Computational analysis of models for 1, 2, and 4 (1a, 2a, and 4a, respectively) concludes that both the An–O and the An–N bonds are predominantly ionic for all three molecules, with the An–O bonds being slightly more covalent. Molecular orbital energy level diagrams indicate the largest 5f-ligand orbital mixing for 4a (Pu), but spatial overlap considerations do not lead to the conclusion that this implies significantly greater covalency in the Pu–ligand bonding. QTAIM bond critical point data suggest that both U–O/U–N and Pu–O/Pu–N are marginally more covalent than the Th analogues.

Synthesis, Molecular and Electronic Structure of UV(O)[N(SiMe3)2]3

Co-reporter:Skye Fortier, Jessie L. Brown, Nikolas Kaltsoyannis, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2012 Volume 51(Issue 3) pp:1625-1633

Publication Date(Web):January 13, 2012

DOI:10.1021/ic201936j

Addition of 1 equiv of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) to U(NR2)3 in hexanes affords U(O)(NR2)3 (2), which can be isolated in 73% yield. Complex 2 is a rare example of a terminal U(V) oxo complex. In contrast, addition of 1 equiv of Me3NO to U(NR2)3 (R = SiMe3) in pentane generates the U(IV) bridging oxo [(NR2)3U]2(μ-O) (3) in moderate yields. Also formed in this reaction, in low yield, is the U(IV) iodide complex U(I)(NR2)3 (4). The iodide ligand in 4 likely originates from residual NaI, present in the U(NR2)3 starting material. Complex 4 can be generated rationally by addition of 0.5 equiv of I2 to a hexane solution of U(NR2)3, where it can be isolated in moderate yield as a tan crystalline solid. The solid-state molecular structures and magnetic susceptibilities of 2, 3, and 4 have been measured. In addition, the electronic structures of 2 and 3 have been investigated by density functional theory (DFT) methods.

Complexes of Cu(I) supported by a tris(ketimine) tripod

Co-reporter:Jeremiah J. Scepaniak, Guang Wu and Trevor W. Hayton

Dalton Transactions 2012 vol. 41(Issue 26) pp:7859-7861

Publication Date(Web):23 Mar 2012

DOI:10.1039/C2DT30101F

Arylation of tris(2-benzylnitrile)amine with PhLi, followed by aqueous work-up, results in the formation of a tripodal tris(ketimine) scaffold, N(ArCNHPh)3. N(ArCNHPh)3 readily coordinates a number of CuI salts, generating complexes that exhibit trigonal pyramidal geometries in the solid-state.

Synthesis and Characterization of [M2(NCtBu2)5] (M=Mn, Fe, Co): Metal Ketimide Complexes with Strong MetalMetal Interactions

Co-reporter:Richard A. Lewis;Simona Morochnik;Alon Chapovetsky;Guang Wu ; Trevor W. Hayton

Angewandte Chemie 2012 Volume 124( Issue 51) pp:12944-12947

Publication Date(Web):

DOI:10.1002/ange.201206790

Synthesis and Characterization of [M2(NCtBu2)5] (M=Mn, Fe, Co): Metal Ketimide Complexes with Strong MetalMetal Interactions

Co-reporter:Richard A. Lewis;Simona Morochnik;Alon Chapovetsky;Guang Wu ; Trevor W. Hayton

Angewandte Chemie International Edition 2012 Volume 51( Issue 51) pp:12772-12775

Publication Date(Web):

DOI:10.1002/anie.201206790

Probing the Reactivity and Electronic Structure of a Uranium(V) Terminal Oxo Complex

Co-reporter:Skye Fortier ; Nikolas Kaltsoyannis ; Guang Wu

Journal of the American Chemical Society 2011 Volume 133(Issue 36) pp:14224-14227

Publication Date(Web):August 18, 2011

DOI:10.1021/ja206083p

Treatment of the U(III)–ylide adduct U(CH2PPh3)(NR2)3 (1, R = SiMe3) with TEMPO generates the U(V) oxo metallacycle [Ph3PCH3][U(O)(CH2SiMe2NSiMe3)(NR2)2] (2) via O-atom transfer, in good yield. Oxidation of 2 with 0.85 equiv of AgOTf affords the neutral U(VI) species U(O)(CH2SiMe2NSiMe3)(NR2)2 (3). The electronic structures of 2 and 3 are investigated by DFT analysis. Additionally, the nucleophilicity of the oxo ligands in 2 and 3 toward Me3SiI is explored.

Synthesis of a Phosphorano-Stabilized U(IV)-Carbene via One-Electron Oxidation of a U(III)-Ylide Adduct

Co-reporter:Skye Fortier ; Justin R. Walensky ; Guang Wu

Journal of the American Chemical Society 2011 Volume 133(Issue 18) pp:6894-6897

Publication Date(Web):April 13, 2011

DOI:10.1021/ja2001133

Addition of the Wittig reagent Ph3P═CH2 to the U(III) tris(amide) U(NR2)3 (R = SiMe3) generates a mixture of products from which the U(IV) complex U═CHPPh3(NR2)3 (2) can be obtained. Complex 2 features a short U═C bond and represents a rare example of a uranium carbene. In solution, 2 exists in equilibrium with the U(IV) metallacycle U(CH2SiMe2NR)(NR2)2 and free Ph3P═CH2. Measurement of this equilibrium as a function of temperature provides ΔHrxn = 11 kcal/mol and ΔSrxn = 31 eu. Additionally, the electronic structure of the U═C bond was investigated using DFT analysis.

High-Valent Uranium Alkyls: Evidence for the Formation of UVI(CH2SiMe3)6

Co-reporter:Skye Fortier ; Justin R. Walensky ; Guang Wu

Journal of the American Chemical Society 2011 Volume 133(Issue 30) pp:11732-11743

Publication Date(Web):June 22, 2011

DOI:10.1021/ja204151v

Oxidation of [Li(DME)3][U(CH2SiMe3)5] with 0.5 equiv of I2, followed by immediate addition of LiCH2SiMe3, affords the high-valent homoleptic U(V) alkyl complex [Li(THF)4][U(CH2SiMe3)6] (1) in 82% yield. In the solid-state, 1 adopts an octahedral geometry as shown by X-ray crystallographic analysis. Addition of 2 equiv of tert-butanol to [Li(DME)3][U(CH2SiMe3)5] generates the heteroleptic U(IV) complex [Li(DME)3][U(OtBu)2(CH2SiMe3)3] (2) in high yield. Treatment of 2 with AgOTf fails to produce a U(V) derivative, but instead affords the U(IV) complex (Me3SiCH2)Ag(μ-CH2SiMe3)U(CH2SiMe3)(OtBu)2(DME) (3) in 64% yield. Complex 3 has been characterized by X-ray crystallography and is marked by a uranium–silver bond. In contrast, oxidation of 2 can be achieved via reaction with 0.5 equiv of Me3NO, producing the heteroleptic U(V) complex [Li(DME)3][U(OtBu)2(CH2SiMe3)4] (4) in moderate yield. We have also attempted the one-electron oxidation of complex 1. Thus, oxidation of 1 with U(OtBu)6 results in formation of a rare U(VI) alkyl complex, U(CH2SiMe3)6 (6), which is only stable below −25 °C. Additionally, the electronic properties of 1–4 have been assessed by SQUID magnetometry, while a DFT analysis of complexes 1 and 6 is also provided.

Differences in actinide metal–ligand orbital interactions: comparison of U(IV) and Pu(IV) β-ketoiminate N,O donor complexes

Co-reporter:David D. Schnaars, Enrique R. Batista, Andrew J. Gaunt, Trevor W. Hayton, Iain May, Sean D. Reilly, Brian L. Scott and Guang Wu

Chemical Communications 2011 vol. 47(Issue 27) pp:7647-7649

Publication Date(Web):08 Jun 2011

DOI:10.1039/C1CC12409A

Syntheses and characterization of UCl2(Aracnac)2, UI2(Aracnac)2, and PuI2(Aracnac)2 are reported (Aracnac denotes a bis-phenyl β-ketoiminate ligand where Ar = 3,5-tBu2C6H3). Structural analyses and computations show significant metal–ligand orbital interaction differences in U(IV)vs.Pu(IV) bonding.

Silylation of the Uranyl Ion Using B(C6F5)3-Activated Et3SiH

Co-reporter:David D. Schnaars, Guang Wu, and Trevor W. Hayton

Inorganic Chemistry 2011 Volume 50(Issue 19) pp:9642-9649

Publication Date(Web):August 15, 2011

DOI:10.1021/ic201385h

Addition of 2 equiv of HSiEt3 to UO2(Aracnac)2 (Aracnac = ArNC(Ph)CHC(Ph)O, Ar = 3,5-tBu2C6H3) in the presence of 1 equiv of B(C6F5)3 results in formation of the U(V) bis(silyloxide) complex [U(OSiEt3)2(Aracnac)2][HB(C6F5)3] (1) in 80% yield. Also produced in the reaction, as a minor product, is U(OSiEt3)(OB{C6F5}3)(Aracnac)2 (2). Interestingly, thermolysis of 1 at 85 °C for 24 h also results in formation of 2, concomitant with production of Et3SiH. Addition of 1 equiv of Cp2Co to 1 results in formation of U(OSiEt3)2(Aracnac)2 (3) and [Cp2Co][HB(C6F5)3] (4), which can be isolated in 61% and 71% yields, respectively. Complexes 1–3 have been characterized by X-ray crystallography, while the solution-phase redox properties of 1 have been measured with cyclic voltammetry.

Comparison of the Redox Chemistry of Primary and Secondary Amides of U(IV): Isolation of a U(VI) Bis(imido) Complex or a Homoleptic U(VI) Amido Complex

Co-reporter:Lani A. Seaman ; Skye Fortier ; Guang Wu

Inorganic Chemistry 2011 Volume 50(Issue 2) pp:636-646

Publication Date(Web):December 13, 2010

DOI:10.1021/ic101847b

Reaction of UCl4 with 6 equiv of LiNHtBu generates the U(IV) homoleptic amide complex [Li(THF)2Cl]2[Li]2[U(NHtBu)6] (1·THF) in 57% yield. In the solid-state, 1·THF exists as a one-dimensional coordination polymer consisting of alternating [Li]2[U(NHtBu)6] and [Li(THF)2Cl]2 building blocks. Recrystallization of 1·THF from DME/hexanes affords the monomeric DME derivative, [Li(DME)2ClLi]2[U(NHtBu)6] (1·DME), which was also characterized by X-ray crystallography. The oxidation of 1·THF with 1 equiv of AgOTF generates the U(VI) bis(imido) complex [Li(THF)]2[U(NtBu)2(NHtBu)4] (2) in low yield. In contrast, oxidation of 1·THF with 1 equiv of I2, in the presence of excess tert-butylamine, cleanly affords the U(VI) bis(imido) U(NtBu)2(NHtBu)2(NH2tBu)2 (3) in 78% yield. We have also explored the reactivity of UCl4 with the lithium salt of a secondary amide. Thus, reaction of 6 equiv of (LiNC5H10) (HNC5H10 = piperidine) with UCl4 in DME produces the U(IV) amide, [Li(DME)][U(NC5H10)5] (4). Oxidation of this material with 0.5 equiv of I2, followed by addition of Li(NC5H10), produces [Li(DME)3][U(NC5H10)6] (5) in moderate yield. Oxidation of 5 with 0.5 equiv of I2 generates U(NC5H10)6 (6) in good yield. The structures of 4−6 were elucidated by X-ray crystallographic analysis, while the magnetic properties of 4 and 5 were investigated by SQUID magnetometry. Additionally, the solution phase redox properties of 5 were examined by cyclic voltammetry.

Facile Reduction of a Uranyl(VI) β-Ketoiminate Complex to U(IV) Upon Oxo Silylation

Co-reporter:Jessie L. Brown ; Charles C. Mokhtarzadeh ; Jeremie M. Lever ; Guang Wu

Inorganic Chemistry 2011 Volume 50(Issue 11) pp:5105-5112

Publication Date(Web):May 5, 2011

DOI:10.1021/ic200387n

Reaction of the uranyl β-ketoiminate complex UO2(tBuacnac)2 (1) (tBuacnac = tBuNC(Ph)CHC(Ph)O) with Me3SiI, in the presence of Ph3P, results in the reductive silylation of the uranyl moiety and formation of the U(V) bis-silyloxide complex [Ph3PI][U(OSiMe3)2I4] (2). Subsequent reaction of 2 with Lewis bases, such as 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), and tetrahydrofuran (THF), results in a further reduction of the metal center and isolation of the U(IV) complexes U(OSiMe3)2I2(bipy)2 (3), U(OSiMe3)2I2(phen)2 (4), and [U(OSiMe3)2I(THF)4][I3] (5), respectively.

Borane-Mediated Silylation of a Metal–Oxo Ligand

Co-reporter:David D. Schnaars ; Guang Wu

Inorganic Chemistry 2011 Volume 50(Issue 11) pp:4695-4697

Publication Date(Web):May 9, 2011

DOI:10.1021/ic2008649

The addition of 1 equiv of HSiPh3 to UO2(Aracnac)2 (Aracnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-tBu2C6H3), in the presence of 1 equiv of B(C6F5)3, results in the formation of U(OSiPh3)(OB{C6F5}3)(Aracnac)2 (1), via silylation of an oxo ligand and reduction of the uranium center. The addition of 1 equiv of Cp2Co to 1 results in a reduction to uranium(IV) and the formation of [Cp2Co][U(OSiPh3)(OB{C6F5}3)(Aracnac)2] (2) in 78% yield. Complexes 1 and 2 have been characterized by X-ray crystallography, while the solution-phase redox properties of 1 have been measured with cyclic voltammetry.

Late-Metal Nitrosyl Cations: Synthesis and Reactivity of [Ni(NO)(MeNO2)3][PF6]

Co-reporter:Ashley M. Wright ; Guang Wu

Inorganic Chemistry 2011 Volume 50(Issue 22) pp:11746-11753

Publication Date(Web):October 27, 2011

DOI:10.1021/ic201821t

The reaction of [NO][PF6] with excess Ni powder in CH3NO2, in the presence of 2 mol % NiI2, results in the formation of [Ni(NO)(CH3NO2)3][PF6] (1), which can be isolated in modest yield as a blue crystalline solid. Also formed in the reaction is [Ni(CH3NO2)6][PF6]2 (2), which can be isolated in comparable yield as a pale-green solid. In the solid state, 1 exhibits tetrahedral geometry about the Ni center with a linear nitrosyl ligand [Ni1–N1–O1 = 174.1(8)°] and a short Ni–N bond distance [1.626(6) Å]. As anticipated, the weakly coordinating nitromethane ligands in 1 are easily displaced by a variety of donors, including Et2O, MeCN, and piperidine (NC5H11). More surprisingly, the addition of mesitylene to 1 results in the formation of an η6-coordinated nickel arene complex, [Ni(η6-1,3,5-Me3C6H3)(NO)][PF6] (6). In the solid state, complex 6 exhibits a long Ni–Ccent distance [1.682(2) Å], suggesting a relatively weak Ni–arene interaction, a consequence of the strong π-back-donation to the nitrosyl ligand. The addition of anisole to 1 also results in the formation of a η6 nickel arene complex, [Ni(η6-MeOC6H5)(NO)][PF6] (7). This complex also exhibits a long Ni–Ccent distance [1.684(1) Å].

Stabilizing High-Valent Metal Ions with a Ketimide Ligand Set: Synthesis of Mn(N═CtBu2)4

Co-reporter:Richard A. Lewis ; Guang Wu

Inorganic Chemistry 2011 Volume 50(Issue 10) pp:4660-4668

Publication Date(Web):April 12, 2011

DOI:10.1021/ic200490v

Reaction of MnCl2 with 4 equiv of Li(N═CtBu2) generates [Li(THF)]2[Mn(N═CtBu2)4] (1) in 80% yield. Oxidation of 1 with 0.5 equiv of I2 produces [Li][Mn(N═CtBu2)4] (2) in 88% yield. Both complexes 1 and 2 exhibit tetrahedral structures about the Mn center in the solid-state, as determined by X-ray crystallography. Reaction of 2 with 12-crown-4 generates [Li(12-crown-4)2][Mn(N═CtBu2)4] (3) in 94% yield. Interestingly, in the solid-state, complex 3 exhibits a squashed tetrahedral structure about Mn. Addition of 1 equiv of I2 to 1 generates the Mn(IV) ketimide, Mn(N═CtBu2)4 (4), in 75% yield. Complex 4 was fully characterized, including analysis by X-ray crystallography and cyclic voltammetry. Like 3, complex 4 also exhibits a squashed tetrahedral structure in the solid-state. Interestingly, thermolysis of complex 4 at 50 °C for 6 h results in the formation of Mn3(N═CtBu2)6 (6), which can be isolated in 49% yield. Also observed in the reaction mixture is pivalonitrile, isobutylene, and isobutene, the products of ketimide ligand oxidation. We have also synthesized the homoleptic Cr(IV) ketimide complex, Cr(N═CtBu2)4 (5), and have analyzed its electrochemical properties with cyclic voltammetry.

Structural Characterization of a Copper Nitrosyl Complex with a {CuNO}10 Configuration

Co-reporter:Ashley M. Wright ; Guang Wu

Journal of the American Chemical Society 2010 Volume 132(Issue 41) pp:14336-14337

Publication Date(Web):September 29, 2010

DOI:10.1021/ja105930b

The synthesis and characterization of a {CuNO}10 complex, namely, [Cu(CH3NO2)5(NO)][PF6]2, has been achieved by the addition of [NO][PF6] to copper metal powder in the presence of nitromethane. In the solid state, this complex exhibits a bent Cu−N−O moiety [Cu−N−O = 121.0(3)°] and a long Cu−N bond. This complex readily reacts with mesitylene to form [mesitylene, NO][PF6] and [Cu(η2-1,3,5-Me3C6H3)2][PF6] by transfer of NO+ to the mesitylene ring.

Oxo Ligand Silylation in a Uranyl β-Ketoiminate Complex

Co-reporter:Jessie L. Brown ; Guang Wu

Journal of the American Chemical Society 2010 Volume 132(Issue 21) pp:7248-7249

Publication Date(Web):May 11, 2010

DOI:10.1021/ja1013739

Addition of Me3SiI to UO2(Aracnac)2 (ArNC(Ph)CHC(Ph)O, Ar = 3,5-tBu2C6H3) (1) results in the formation of U(OSiMe3)2I2(Aracnac) (2) in moderate yield. Also formed in the reaction are I2 and ArNC(Ph)═CHC(Ph)OSiMe3, the product of [Aracnac]− abstraction by Me3Si+. In contrast, reaction of 1 with Me3SiX (X = Cl, OTf) only results in the formation of UO2(OTf)2(AracnacH)2(Et2O) (3) and UO2Cl2(AracnacH)2 (4), respectively.

Synthesis of a Nitrido-Substituted Analogue of the Uranyl Ion, [N═U═O]+

Co-reporter:Skye Fortier ; Guang Wu

Journal of the American Chemical Society 2010 Volume 132(Issue 20) pp:6888-6889

Publication Date(Web):May 4, 2010

DOI:10.1021/ja101567h

Addition of 0.5 equiv of NaN3 to U[NR2]3 (R = SiMe3) affords the metallacycle [Na(DME)2(TMEDA)][(NR2)2U(μ-N)(CH2SiMe2NR)U(NR2)2] (1) in 69% yield. Complex 1 is readily oxidized by 0.5 equiv of I2, generating the mixed valent U(IV/V) nitrido complex (NR2)2U(μ-N)(CH2SiMe2NR)U(NR2)2 (2). Alternatively, oxidation of 1 with 1 equiv of Me3NO affords the oxo-nitrido complex [Na(DME)2][(NR2)2(O)U(μ-N)(CH2SiMe2NR)U(NR2)2] (3) in good yield. The solid-state molecular structures of 1−3 have been determined by X-ray crystallography. A notable feature of these complexes are the inequivalent U═N—U bonding interactions. Moreover, 3 contains a trans oxo-nitrido [O═U═N]+ moiety with metrical parameters approximating those of the uranyl cation, UO22+. The magnetic properties of 1−3 were investigated by SQUID magnetometry.

Synthesis and Characterization of an Iron(IV) Ketimide Complex

Co-reporter:Richard A. Lewis ; Guang Wu

Journal of the American Chemical Society 2010 Volume 132(Issue 37) pp:12814-12816

Publication Date(Web):August 25, 2010

DOI:10.1021/ja104934n

Addition of 4 equiv of LiN═CtBu2 to FeCl2 in Et2O/THF results in the formation of [Li(THF)]2[Fe(N═CtBu2)4] (1). Oxidation of 1 with 0.5 equiv of I2 in Et2O/DME yields [Li(DME)][Fe(N═CtBu2)4] (2) in moderate yield. Both 1 and 2 are high spin and exhibit tetrahedral geometries in the solid state. Oxidation of 1 with 1 equiv of I2 in Et2O yields Fe(N═CtBu2)4 (3) in good yield. Surprisingly, complex 3 exhibits a diamagnetic ground state and a nearly square planar geometry about the Fe center.

Oxo ligand functionalization in the uranyl ion (UO22+)

Co-reporter:Skye Fortier, Trevor W. Hayton

Coordination Chemistry Reviews 2010 Volume 254(3–4) pp:197-214

Publication Date(Web):February 2010

DOI:10.1016/j.ccr.2009.06.003

Uranyl (UO22+) is an exceptionally stable molecular species, characterized by a linear OUO geometry and short U–O bonds. Its two oxo ligands are thought to be inert to exchange and resistant to functionalization. However, a growing body of literature suggests that this assessment may need to be reevaluated. This review summarizes the chemistry of the two oxo ligands of the uranyl ion. In particular, we explore the interaction of the uranyl oxo ligands with Lewis acids, and outline attempts to selectively functionalize the oxo ligands of uranyl by chemical means. We also discuss the kinetic and mechanistic knowledge for oxo ligand exchange under acidic, basic and photolytic conditions.

U(IV) and U(V) azide complexes supported by amide or aryloxide ligands

Co-reporter:Skye Fortier, Guang Wu and Trevor W. Hayton

Dalton Transactions 2010 vol. 39(Issue 2) pp:352-354

Publication Date(Web):24 Jul 2009

DOI:10.1039/B909879H

The uranium(IV) azides [Li(THF)3]2[U(OAr)4(N3)2], Ar = 2,6-Me2C6H3, and {[Na(THF)4][U[N(SiMe3)2]3(N3)2]}x have been synthesised and structurally characterised. Oxidation of these complexes affords [Li(THF)3][U(OAr)5(N3)] and U[N(SiMe3)2]3(N3)2, which are the first azides of U(V).

Metal–ligand multiple bonding in uranium: structure and reactivity

Co-reporter:Trevor W. Hayton

Dalton Transactions 2010 vol. 39(Issue 5) pp:1145-1158

Publication Date(Web):16 Nov 2009

DOI:10.1039/B909238B

There is a growing interest in uranium coordination chemistry, particularly as it relates to metal–ligand multiple bonding, and in the last decade significant progress has been made in synthesizing oxo, imido, μ-nitrido, and carbene-containing complexes of uranium. This review summarizes the synthesis, structure and reactivity of these complexes, starting from the inception of the field in 1981. Particular attention is focused on the recent developments in this area, such as the synthesis of the bis(imido) analogues of the uranyl ion, and the isolation of the first μ-nitrido complexes of this element.

Isolation of a uranyl amide by “ate” complex formation

Co-reporter:Lani A. Seaman, David D. Schnaars, Guang Wu and Trevor W. Hayton

Dalton Transactions 2010 vol. 39(Issue 29) pp:6635-6637

Publication Date(Web):25 Mar 2010

DOI:10.1039/C001976C

The uranyl amide [{Li(DME)}2Cl][Li(DME)][UO2(NC5H10)3]2 has been synthesised and structurally characterised. Its stability is attributed to the saturation of the uranyl coordination sphere by “ate” complex formation.

Homoleptic Uranium(IV) Alkyl Complexes: Synthesis and Characterization

Co-reporter:Skye Fortier ; Brent C. Melot ; Guang Wu

Journal of the American Chemical Society 2009 Volume 131(Issue 42) pp:15512-15521

Publication Date(Web):October 2, 2009

DOI:10.1021/ja906516e

The addition of 4.5 equiv of LiCH2SiMe3 to [Li(THF)]2[U(OtBu)6], in the presence of LiCl, results in the formation of the homoleptic uranium(IV) alkyl complex [Li14(OtBu)12Cl][U(CH2SiMe3)5] (1) in low yield. Complex 1 has been characterized by X-ray crystallography. As a solid, 1 is thermally stable for several days at room temperature. However, 1 rapidly decomposes in C6D6, as indicated by 1H and 7Li{1H} NMR spectroscopy, owing to the lability of the [Li14(OtBu)12Cl]+ cation. To avoid the formation of the [Li14(OtBu)12Cl]+ counterion, alkylation of UCl4 was investigated. Treatment of UCl4 with 5 equiv of LiCH2SiMe3 or LiCH2tBu at −25 °C in THF/Et2O affords [Li(DME)3][U(CH2SiMe3)5] (2) and [Li(THF)4][U(CH2tBu)5] (3), respectively, in good yields. Similarly, treatment of UCl4 with 6 equiv of MeLi or KCH2C6H5 generates the U(IV) hexa(alkyl) complexes [Li(TMEDA)]2[UMe6] (4) and {[K(THF)]3[K(THF)2][U(CH2C6H5)6]2}x (5) in 38% and 70% yields, respectively. The structures of 3−5 have been confirmed by X-ray crystallography. Complexes 2, 3, and 5 are thermally stable solids which can be stored at room temperature for several days, whereas 4 decomposes upon warming above −25 °C. The electronic and magnetic properties of 2, 3, and 5 were also investigated by NIR spectroscopy and SQUID magnetometry.

Reduction of Pentavalent Uranyl to U(IV) Facilitated by Oxo Functionalization

Co-reporter:David D. Schnaars ; Guang Wu

Journal of the American Chemical Society 2009 Volume 131(Issue 48) pp:17532-17533

Publication Date(Web):November 16, 2009

DOI:10.1021/ja906880d

Addition of 2 equiv of B(C6F5)3 to [Cp*2Co][UVO2(Aracnac)2] (1) [Aracnac = ArNC(Ph)CHC(Ph)O; Ar = 3,5-tBu2C6H3] results in the formation of [Cp*2Co][UV{OB(C6F5)3}2(Aracnac)2] (2) in good yield. Reduction of 2 with 1 equiv of Cp*2Co generates [Cp*2Co]2[UIV{OB(C6F5)3}2(Aracnac)2] (3), also in good yield. This reaction is chemically reversible, as shown by the reaction of 3 with AgOTf, which regenerates 2. Interestingly, addition of only 1 equiv of B(C6F5)3 to 1 does not produce the monofunctionalized U(V) complex. Instead, the products of disproportionation, namely, 3 and UVIO2(Aracnac)2, are observed in a 1:1 ratio.

Synthesis and Redox Chemistry of High-Valent Uranium Aryloxides

Co-reporter:Skye Fortier ; Guang Wu

Inorganic Chemistry 2009 Volume 48(Issue 7) pp:3000-3011

Publication Date(Web):February 26, 2009

DOI:10.1021/ic802266y

Alcoholysis of U(OtBu)6 with 1 or 2 equiv of C6F5OH generates U(OtBu)5(OC6F5) (1) and U(OtBu)4(OC6F5)2 (2) in 70% and 65% yields, respectively. Complexes 1 and 2 have been fully characterized, and their solution redox properties have been determined by cyclic voltammetry. Complex 1 exhibits a reversible reduction feature at E1/2 = −0.60 V (vs [Cp2Fe]0/+), while 2 exhibits a reversible reduction feature at −0.24 V (vs [Cp2Fe]0/+). Attempts to isolate the other tert-butoxide/pentafluorophenoxide complexes, U(OtBu)6-n(OC6F5)n (n = 3−6), did not generate the intended products. For instance, reaction of U(OtBu)6 with 6 equiv of C6F5OH in CH2Cl2 results in the formation [Li(HOtBu)2][U(OC6F5)6] (3). The source of the lithium cation in 3 is likely LiI, which is present from the initial synthesis of the U(OtBu)6. However, reaction of LiI-free U(OtBu)6 with 6 equiv of C6F5OH results in the formation of a uranyl complex, UO2(OC6F5)2(HOtBu)2 (4), along with isobutylene and tBuOC6F5. To probe the mechanism of this transformation, U(OtBu)6 was reacted with C6F518OH·0.5DME. This produces UO2(18OC6F5)2(DME) (5-18O) along with tBu18OC6F5 as determined by GC/MS, which suggests that oxo formation only occurs by tert-butyl cation elimination and not aromatic nucleophilic substitution. Several other synthetic pathways to UVI(OC6F5)6 were also investigated. Thus, addition of 10 equiv of C6F5OH to [Li(THF)]2[U(OtBu)6] in Et2O followed by addition of DME results in the formation of [Li(DME)3]2[U(OC6F5)6] (7). Oxidation of 7 with 2 equiv of AgOTf in CH2Cl2 or toluene generates [Li(DME)3][U(OC6F5)6] (8) or [Ag(η2-C7H8)2(DME)][U(OC6F5)6] (9), respectively. However, no evidence for the formation of UVI(OC6F5)6 was observed during these reactions.

Coordination of N-Donor Ligands to a Uranyl(V) β-Diketiminate Complex

Co-reporter:Michael F. Schettini, Guang Wu and Trevor W. Hayton

Inorganic Chemistry 2009 Volume 48(Issue 24) pp:11799-11808

Publication Date(Web):November 30, 2009

DOI:10.1021/ic9018508

Addition of 2 equiv of AgOTf to [UO2(Ar2nacnac)Cl]2 (Ar2nacnac = {(2,6-Pri2C6H3)NC(Me)}2CH) in the presence of excess pyridine, followed by addition of Cp2Co, generates the uranyl(V) complex UO2(Ar2nacnac)(py)2 (2), in moderate yield. Complex 2 has proven to be an excellent precursor for the synthesis of other U(V) complexes. Thus, addition of 2,2′-bipyridine (bipy), 1,10-phenanthroline (phen), TMEDA, or 1-methylimidazole (MeIm) to 2 provides UO2(Ar2nacnac)(bipy) (3), UO2(Ar2nacnac)(phen) (4), UO2(Ar2nacnac)(TMEDA) (5), and UO2(Ar2nacnac)(MeIm)2 (6), respectively. Complexes 2−6 have been fully characterized and their structures confirmed by X-ray crystallography. Attempts to form the analogous hexavalent uranyl complexes of bipy, phen, and TMEDA have not been successful. However, reaction of [UO2(Ar2nacnac)Cl]2 with AgOTf and 2 equiv of MeIm leads to the isolation of [UO2(Ar2nacnac)(MeIm)2][OTf] (7), which has been fully characterized. Attempts to ligate sulfur donor ligands to either the UO2(Ar2nacnac) or the [UO2(Ar2nacnac)]+ fragments were unsuccessful.

Exploring the Effects of Reduction or Lewis Acid Coordination on the U═O Bond of the Uranyl Moiety

Co-reporter:Trevor W. Hayton ;Guang Wu

Inorganic Chemistry 2009 Volume 48(Issue 7) pp:3065-3072

Publication Date(Web):March 5, 2009

DOI:10.1021/ic802360y

Reaction of Li(ArNC(Ph)CHC(Ph)O) (Aracnac; Ar = 2,4,6-Me3C6H2) or Na(ArNC(Ph)CHC(Ph)O) (Ar = 3,5-tBu2C6H3) with 0.5 equiv of UO2Cl2(THF)3 results in the formation of UO2(Aracnac)2 (Ar = 2,4,6-Me3C6H2, 1; 3,5-tBu2C6H3, 2), which were isolated as orange crystalline solids in good yields. The structure of 2 has been confirmed by X-ray crystallography, while the solution redox properties of 1 and 2 have been measured by cyclic voltammetry. Complex 1 exhibits a reversible reduction feature at E1/2 = −1.52 V (vs Fc/Fc+), while complex 2 exhibits a reduction feature at −1.35 V (vs Fc/Fc+). Complexes 1 and 2 react with Cp*2Co to generate [Cp*2Co][UO2(Aracnac)2] (Ar = 2,4,6-Me3C6H2, 3; 3,5-tBu2C6H3, 4), in moderate to good yields. Both 3 and 4 have been fully characterized, while the structure of 4 has also been determined by X-ray crystallography. Reaction of 2 with 2 equiv of B(C6F5)3 in CH2Cl2 leads to the isolation of UO(OB{C6F5}3)(Aracnac)2 (Ar = 3,5-tBu2C6H3) (5). Complex 5, generated in situ, exhibits an irreversible reduction at −0.78 V (vs Fc/Fc+, 100 mV/s scan rate) which is considerably lower than the reduction potential observed for 2, consistent with the removal of electron density from the uranyl moiety by coordination of B(C6F5)3.

Reactivity of UI4(OEt2)2 with phenols: probing the chemistry of the U–I bond

Co-reporter:David D. Schnaars, Guang Wu and Trevor W. Hayton

Dalton Transactions 2009 (Issue 19) pp:3681-3687

Publication Date(Web):12 Mar 2009

DOI:10.1039/B823002A

Solutions of UI4(OEt2)2 in Et2O were found to deposit orange crystals of [H(OEt2)2][UI5(OEt2)] (1) upon standing at room temperature. The proton in the cation of 1 most likely originates from the surface of the glass vial in which the solution was stored. Reactions of UI4(OEt2)2 with 1 equiv. of ArOH in toluene, followed by addition of THF, provides UI3(OAr)(THF)x (Ar = Ph, x = 3, 2; Ar = 2,6-Ph2C6H3, x = 2, 3). UI4(OEt2)2 also reacts with 2 equiv. of ArOH (Ar = Ph, 4-tBuC6H4, 2,6-Me2C6H3, C6F5) in toluene, followed by addition of THF, to generate UI2(OC6H5)2(THF)3 (4), UI2(O-4-tBuC6H4)2(THF)3 (5), UI2(O-2,6-Me2C6H3)2(THF)3 (6) and UI2(OC6F5)2(THF)3 (7), in moderate yields. Complete conversion to the products requires the use of a dynamic vacuum to remove the HI generated upon addition of the phenol.

Mixed-Ligand Uranyl(V) β-Diketiminate/β-Diketonate Complexes: Synthesis and Characterization

Co-reporter:Trevor W. Hayton and Guang Wu

Inorganic Chemistry 2008 Volume 47(Issue 16) pp:7415-7423

Publication Date(Web):July 17, 2008

DOI:10.1021/ic800778j

The reaction of [UO2(Ar2nacnac)Cl]2 [Ar2nacnac = (2,6-iPr2C6H3)NC(Me)CHC(Me)N(2,6-iPr2C6H3)] with Na(RC(O)CHC(O)R) (R = Me, Ph, CF3) in tetrahydrofuran results in the formation of UO2(Ar2nacnac)(RC(O)CHC(O)R) (R = Me, 1; Ph, 2; CF3, 3), which can be isolated in moderate yields. The structures of 1 and 2 have been confirmed by X-ray crystallography, while the solution redox properties of 1−3 have been measured by cyclic voltammetry. Complexes 1−3 exhibit reduction features at −1.82, −1.59, and −1.39 V (vs Fc/Fc+), respectively, at a scan rate of 100 mV·s−1. The decrease in the reduction potential follows the electron-withdrawing ability of each β-diketonate ligand. Chemical reduction of 1 and 2 with Cp*2Co in toluene yields [Cp*2Co][UO2(Ar2nacnac)(RC(O)CHC(O)R)] (R = Me, 4; Ph, 5), while reduction of 3 with Cp2Co provides [Cp2Co][UO2(Ar2nacnac)(CF3C(O)CHC(O)CF3)] (6). Complexes 4−6 have been fully characterized, while the solid-state molecular structure of 5 has also been determined. In contrast to the clean reduction that occurs with Cp*2Co, reduction of 1 with sodium ribbon, followed by cation exchange with [NEt4]Cl, produces [NEt4][UO2(Ar2nacnac)(H2C═C(O)CH(O)CMe)] (7) in modest yield. This product results from the formal loss of H• from a methyl group of the acetylacetonate ligand. Alternately, complex 7 can be synthesized by deprotonation of 1 with NaNTMS2 in good yield.

Synthesis and Characterization of Three Homoleptic Alkoxides of Uranium: [Li(THF)]2[UIV(OtBu)6], [Li(Et2O)][UV(OtBu)6], and UVI(OtBu)6

Co-reporter:Skye Fortier ; Guang Wu

Inorganic Chemistry 2008 Volume 47(Issue 11) pp:4752-4761

Publication Date(Web):April 16, 2008

DOI:10.1021/ic800067k

Addition of 6 equiv of LiOtBu to a THF/Et2O solution of UCl4 at −25 °C generates [Li(THF)]2[U(OtBu)6] (1) in 61% yield. 1 is soluble in polar organic solvents and is stable for several days in THF. However, 1 slowly decomposes in benzene or hexanes, forming the dinuclear uranium(IV) species [Li(THF)][U2(OtBu)9] (2) as one of the decomposition products. Alternatively, 2 can be directly prepared in moderate yield by the addition of 4.5 equiv LiOtBu to UCl4 in hexanes/THF at room temperature. The decomposition of 1 has been studied by 1H and 7Li{1H} NMR spectroscopies to elucidate the nature of this transformation. Oxidation of 1 occurs readily in the presence of 0.5 or 1 equiv of I2 to give [Li(Et2O)][U(OtBu)6] (3) and U(OtBu)6 (4), respectively, in good yields. Alternately, 3 can be generated by comproportionation of 1 and 4. 1−4 have been fully characterized, including analysis by X-ray crystallography. In the solid-state these complexes possess large U−O−Cq bond angles, suggestive of a significant U−O π interaction. In addition, we have studied the redox properties of 4 by cyclic voltammetry.

Reactivity of UH3 with mild oxidants

Co-reporter:David D. Schnaars, Guang Wu and Trevor W. Hayton

Dalton Transactions 2008 (Issue 44) pp:6121-6126

Publication Date(Web):06 Oct 2008

DOI:10.1039/B809184F

Addition of 2 equiv of I2 to a stirring suspension of UH3 in Et2O results in vigorous gas evolution and the formation of UI4(OEt2)2 (1), which can be isolated in good yields as an air- and moisture-sensitive brick-red powder. Addition of 3 equiv of AgBr to UH3 in DME produces UBr3(DME)2 (2), while addition of 4 equiv of AgX to UH3 in DME–CH2Cl2 provides UX4(DME)2 (X = Br, 3; Cl, 4). Similarly, the reaction of 4 equiv of AgOTf with UH3 in neat DME generates U(OTf)4(DME)2 (5). Each of these reactions proceeds with the evolution of hydrogen. Complex 1 can also be generated by reaction of 4 equiv of Me3SiI with UCl4 in Et2O. All complexes were fully characterized, including analysis by X-ray crystallography.

Synthesis, structure and bonding of hexaphenyl thorium(IV): observation of a non-octahedral structure

Co-reporter:Elizabeth A. Pedrick, Peter Hrobárik, Lani A. Seaman, Guang Wu and Trevor W. Hayton

Chemical Communications 2016 - vol. 52(Issue 4) pp:NaN692-692

Publication Date(Web):2015/11/09

DOI:10.1039/C5CC08265J

Synthesis of a cobalt(IV) ketimide with a squashed tetrahedral geometry

Co-reporter:Richard A. Lewis, Stephen P. George, Alon Chapovetsky, Guang Wu, Joshua S. Figueroa and Trevor W. Hayton

Chemical Communications 2013 - vol. 49(Issue 28) pp:NaN2890-2890

Publication Date(Web):2013/02/22

DOI:10.1039/C3CC40461G

Recent developments in actinide–ligand multiple bonding

Co-reporter:Trevor W. Hayton

Chemical Communications 2013 - vol. 49(Issue 29) pp:NaN2973-2973

Publication Date(Web):2013/01/31

DOI:10.1039/C3CC39053E

Differences in actinide metal–ligand orbital interactions: comparison of U(IV) and Pu(IV) β-ketoiminate N,O donor complexes

Co-reporter:David D. Schnaars, Enrique R. Batista, Andrew J. Gaunt, Trevor W. Hayton, Iain May, Sean D. Reilly, Brian L. Scott and Guang Wu

Chemical Communications 2011 - vol. 47(Issue 27) pp:NaN7649-7649

Publication Date(Web):2011/06/08

DOI:10.1039/C1CC12409A

Synthesis and reactivity of a uranyl-imidazolyl complex

Co-reporter:Michael F. Schettini, Guang Wu and Trevor W. Hayton

Chemical Communications 2012 - vol. 48(Issue 10) pp:NaN1486-1486

Publication Date(Web):2011/08/22

DOI:10.1039/C1CC13192C

Thorium–ligand multiple bonds via reductive deprotection of a trityl group

Co-reporter:Danil E. Smiles, Guang Wu, Nikolas Kaltsoyannis and Trevor W. Hayton

Chemical Science (2010-Present) 2015 - vol. 6(Issue 7) pp:NaN3899-3899

Publication Date(Web):2015/04/30

DOI:10.1039/C5SC01248A

Reductive silylation of a uranyl dibenzoylmethanate complex: an example of controlled uranyl oxo ligand cleavage

Co-reporter:E. A. Pedrick, G. Wu, N. Kaltsoyannis and T. W. Hayton

Chemical Science (2010-Present) 2014 - vol. 5(Issue 8) pp:NaN3213-3213

Publication Date(Web):2014/05/23

DOI:10.1039/C4SC00996G

U(IV) and U(V) azide complexes supported by amide or aryloxide ligands

Co-reporter:Skye Fortier, Guang Wu and Trevor W. Hayton

Dalton Transactions 2010 - vol. 39(Issue 2) pp:NaN354-354

Publication Date(Web):2009/07/24

DOI:10.1039/B909879H

Metal–ligand multiple bonding in uranium: structure and reactivity

Co-reporter:Trevor W. Hayton

Dalton Transactions 2010 - vol. 39(Issue 5) pp:NaN1158-1158

Publication Date(Web):2009/11/16

DOI:10.1039/B909238B

Reactivity of UI4(OEt2)2 with phenols: probing the chemistry of the U–I bond

Co-reporter:David D. Schnaars, Guang Wu and Trevor W. Hayton

Dalton Transactions 2009(Issue 19) pp:NaN3687-3687

Publication Date(Web):2009/03/12

DOI:10.1039/B823002A

Reactivity of UH3 with mild oxidants

Co-reporter:David D. Schnaars, Guang Wu and Trevor W. Hayton

Dalton Transactions 2008(Issue 44) pp:NaN6126-6126

Publication Date(Web):2008/10/06

DOI:10.1039/B809184F

Activation of CS2 by a “masked” terminal nickel sulfide

Co-reporter:Nathaniel J. Hartmann, Guang Wu and Trevor. W. Hayton

Dalton Transactions 2016 - vol. 45(Issue 37) pp:NaN14510-14510

Publication Date(Web):2016/04/26

DOI:10.1039/C6DT00885B

The “masked” terminal nickel sulfide complexes [K(L)][(LtBu)NiII(S)] (LtBu = {(2,6-iPr2C6H3)NC(tBu)}2CH, L = 18-crown-6, 2,2,2-cryptand) activate CS2 to give the trithiocarbonate products [(LtBu)NiII(S,S:κ2-CS3)]− or [(S,S:κ2-CS3)NiII{S,S:κ2-CS2(LtBu)}]−, further confirming the nucleophilicity of the sulfide (S2−) ligand in these complexes.

Isolation of a uranyl amide by “ate” complex formation

Co-reporter:Lani A. Seaman, David D. Schnaars, Guang Wu and Trevor W. Hayton

Dalton Transactions 2010 - vol. 39(Issue 29) pp:NaN6637-6637

Publication Date(Web):2010/03/25

DOI:10.1039/C001976C

Complexes of Cu(I) supported by a tris(ketimine) tripod

Co-reporter:Jeremiah J. Scepaniak, Guang Wu and Trevor W. Hayton

Dalton Transactions 2012 - vol. 41(Issue 26) pp:NaN7861-7861

Publication Date(Web):2012/03/23

DOI:10.1039/C2DT30101F