Co-reporter:Khetpakorn Chakarawet;Zachary W. Davis-Gilbert;Stephanie R. Harstad;Dr. Victor G. Young Jr.; Jeffrey R. Long; John E. Ellis
Angewandte Chemie International Edition 2017 Volume 56(Issue 35) pp:10577-10581
Publication Date(Web):2017/08/21
DOI:10.1002/anie.201706323
AbstractHexakis(2,6-diisopropylphenylisocyanide)tantalum is the first isocyanide analogue of the highly unstable Ta(CO)6 and represents the only well-defined zerovalent tantalum complex to be prepared by conventional laboratory methods. Two prior examples of homoleptic Ta0 complexes are known, Ta(benzene)2 and Ta(dmpe)3, dmpe=1,2-bis(dimethylphosphano)ethane, but these have only been accessed via ligand co-condensation with tantalum vapor in a sophisticated metal-atom reactor. Consistent with its 17-electron nature, Ta(CNDipp)6 undergoes facile one-electron oxidation, reduction, or disproportionation reactions. In this sense, it qualitatively resembles V(CO)6, the only paramagnetic homoleptic metal carbonyl isolable under ambient conditions.
Co-reporter:Khetpakorn Chakarawet;Zachary W. Davis-Gilbert;Stephanie R. Harstad;Dr. Victor G. Young Jr.; Jeffrey R. Long; John E. Ellis
Angewandte Chemie 2017 Volume 129(Issue 35) pp:10713-10717
Publication Date(Web):2017/08/21
DOI:10.1002/ange.201706323
AbstractHexakis(2,6-diisopropylphenylisocyanide)tantalum is the first isocyanide analogue of the highly unstable Ta(CO)6 and represents the only well-defined zerovalent tantalum complex to be prepared by conventional laboratory methods. Two prior examples of homoleptic Ta0 complexes are known, Ta(benzene)2 and Ta(dmpe)3, dmpe=1,2-bis(dimethylphosphano)ethane, but these have only been accessed via ligand co-condensation with tantalum vapor in a sophisticated metal-atom reactor. Consistent with its 17-electron nature, Ta(CNDipp)6 undergoes facile one-electron oxidation, reduction, or disproportionation reactions. In this sense, it qualitatively resembles V(CO)6, the only paramagnetic homoleptic metal carbonyl isolable under ambient conditions.
Co-reporter:Benjamin E. Kucera;Robert E. Jilek;William W. Brennessel
Acta Crystallographica Section C 2014 Volume 70( Issue 8) pp:749-753
Publication Date(Web):
DOI:10.1107/S2053229614015290
Reduction of VCl3(THF)3 (THF is tetrahydrofuran) and NbCl4(THF)2 by alkali metal pyrene radical anion salts in THF affords the paramagnetic sandwich complexes bis[(1,2,3,3a,10a,10b-η)-pyrene]vanadium(0), [V(C16H10)2], and bis[(1,2,3,3a,10a,10b-η)-pyrene]niobium(0), [Nb(C16H10)2]. Treatment of tris(naphthalene)titanate(2−) with pyrene provides the isoelectronic titanium species, isolated as an (18-crown-6)potassium salt, namely catena-poly[[(18-crown-6)potassium]-μ-[(1,2-η:1,2,3,3a,10a,10b-η)-pyrene]-titanate(−I)-μ-[(1,2,3,3a,10a,10b-η:6,7-η)-pyrene]], {[K(C12H24O6)][Ti(C16H10)2]}n. The first two compounds have very similar packing, with neighboring molecules arranged orthogonally to one another, such that aromatic donor–acceptor interactions are likely responsible for the specific arrangement. The asymmetric unit contains a half-occupancy metal center η6-coordinated to one pyrene ligand, with the full M(pyrene)2 molecule generated by a crystallographic inversion center. In the titanium compound, the cations and anions are in alternating contact throughout the crystal structure, in one-dimensional chains along the [101] direction. As in the other two compounds, the asymmetric unit contains a half-occupancy Ti atom η6-coordinated to one pyrene ligand. Additionally, the asymmetric unit contains one half of an (18-crown-6)potassium cation, located on a crystallographic inversion center coincident with the K atom. The full formula units are generated by those inversion centers. In all three structures, the pyrene ligands are eclipsed and sandwich the metals in one of two inversion-related sites. These species are of interest as the first isolable homoleptic pyrene transition metal complexes to be described in the scientific literature.
Co-reporter:William W. Brennessel and John E. Ellis
Inorganic Chemistry 2012 Volume 51(Issue 16) pp:9076-9094
Publication Date(Web):August 9, 2012
DOI:10.1021/ic301240u
Reductions of CoBr2 or cobaltocene by 3 equiv of potassium anthracene radical anion in tetrahydrofuran (THF) afford 60–80% yields of bis(anthracene)cobaltate(1−) (1), of interest as a readily accessible and quite labile source of spin-paired atomic Co–. Although the unsolvated potassium salt of 1 is thermally unstable at 20 °C, the [K(18-crown-6)(THF)2]+ salt of 1 functions as a useful storable crystalline reagent for Co– in several reactions. Previously known classic cobaltates, [CoL4]−, for L = 1/2 (1,3-butadiene) (2), PF3 (3), and P(OiPr)3 (5), were obtained directly from 1 and structurally characterized for the first time. Anion 3 is noteworthy because it appears to possess the shortest known Co–P distance, av = 2.012(4) Å. Although the naphthalene analogue of 1 is not yet available as a pure substance, low-temperature reductions of CoBr2 or cobaltocene by naphthalene radical anion in the presence of 1,5-cyclooctadiene (COD) afford variable yields (80–90% from CoCp2) of (naphthalene)(COD)cobaltate(1−) (10). Ready displacement of naphthalene in 10 by L = 1,3-butadiene, 2,2′-bipyridine, and COD occurs to give good yields of the respective [Co(L)(COD)]−, all of which have been structurally characterized. Both ligands in 10 are displaced by tert-butylisocyanide to afford [Co(CNtBu)4]− (16), the first isolable and structurally characterized homoleptic alkylisocyanometalate. The molecular structure of 16 shows unprecedented bending of the isocyanides, av C–N–C = 137(2)°, for homoleptic isocyanide complexes.
Co-reporter:Victor J. Sussman and John E. Ellis
Chemical Communications 2008 (Issue 43) pp:5642-5644
Publication Date(Web):01 Oct 2008
DOI:10.1039/B811320C
For the first time [N(PPh3)2]+, or [PPN]+, has been shown to undergo an irreversible reaction with a transition metal complex under ambient conditions and affords a product containing a unique structural motif in which two phenyl groups on onePPh3 substituent of [PPN]+ are ortho-metallated, while the third phenyl ring is hydrogenated to provide a tantalum bound 1,3-cyclohexadiene group.
Co-reporter:RobertE. Jilek;Meehae Jang Dr.;EricD. Smolensky;J.Doyle Britton ;JohnE. Ellis
Angewandte Chemie International Edition 2008 Volume 47( Issue 45) pp:8692-8695
Publication Date(Web):
DOI:10.1002/anie.200802780
Co-reporter:RobertE. Jilek;Meehae Jang Dr.;EricD. Smolensky;J.Doyle Britton ;JohnE. Ellis
Angewandte Chemie 2008 Volume 120( Issue 45) pp:8820-8823
Publication Date(Web):
DOI:10.1002/ange.200802780
Co-reporter:Victor J. Sussman and John E. Ellis
Chemical Communications 2008(Issue 43) pp:NaN5644-5644
Publication Date(Web):2008/10/01
DOI:10.1039/B811320C
For the first time [N(PPh3)2]+, or [PPN]+, has been shown to undergo an irreversible reaction with a transition metal complex under ambient conditions and affords a product containing a unique structural motif in which two phenyl groups on onePPh3 substituent of [PPN]+ are ortho-metallated, while the third phenyl ring is hydrogenated to provide a tantalum bound 1,3-cyclohexadiene group.