1050359-32-4Relevant academic research and scientific papers
Diniobium inverted sandwich complexes with μ-η6:η6-arene ligands: Synthesis, kinetics of formation, and electronic structure
Gianetti, Thomas L.,Nocton, Grégory,Minasian, Stefan G.,Tomson, Neil C.,Kilcoyne, A. L. David,Kozimor, Stosh A.,Shuh, David K.,Tyliszczak, Tolek,Bergman, Robert G.,Arnold, John
, p. 3224 - 3236 (2013/04/23)
Monometallic niobium arene complexes [Nb(BDI)(NtBu)(R-C6H5)] (2a: R = H and 2b: R = Me, BDI = N,N′-diisopropylbenzene-β-diketiminate) were synthesized and found to undergo slow conversion into the diniobium inverted arene sandwich complexes [[(BDI)Nb(NtBu)]2(μ-RC6H5)] (7a: R = H and 7b: R = Me) in solution. The kinetics of this reaction were followed by 1H NMR spectroscopy and are in agreement with a dissociative mechanism. Compounds 7a-b showed a lack of reactivity toward small molecules, even at elevated temperatures, which is unusual in the chemistry of inverted sandwich complexes. However, protonation of the BDI ligands occurred readily on treatment with [H(OEt2)][B(C6F5)4], resulting in the monoprotonated cationic inverted sandwich complex 8 [[(BDI#)Nb(NtBu)][(BDI)Nb(NtBu)](μ-C6H5)][B(C6F5)4] and the dicationic complex 9 [[(BDI#)Nb(NtBu)]2(μ-RC6H5)][B(C6F5)4]2 (BDI# = (ArNC(Me))2CH2). NMR, UV-vis, and X-ray absorption near-edge structure (XANES) spectroscopies were used to characterize this unique series of diamagnetic molecules as a means of determining how best to describe the Nb-arene interactions. The X-ray crystal structures, UV-vis spectra, arene 1H NMR chemical shifts, and large JCH coupling constants provide evidence for donation of electron density from the Nb d-orbitals into the antibonding π system of the arene ligands. However, Nb L3,2-edge XANES spectra and the lack of sp3 hybridization of the arene carbons indicate that the Nb → arene donation is not accompanied by an increase in Nb formal oxidation state and suggests that 4d2 electronic configurations are appropriate to describe the Nb atoms in all four complexes.
An unusally diverse array of products formed upon carbonylation of a dialkylniobium complex
Tomson, Neil C.,Yan, Andrew,Arnold, John,Bergman, Robert G.
, p. 11262 - 11263 (2009/02/05)
The reaction of carbon monoxide with a β-diketiminato dimethyl niobium complex (BDI)Me2Nb(NtBu) is shown to lead to a variety of products whose distribution displays a remarkable dependence onthe reaction conditions. Among these, the products of metal reduction, enediolate formation, and intramolecular C-H activation have been fully characterized. An investigation into the individual steps leading to these products points to a transient initial monoacyl complex, whose fate may be perturbed via reaction conditions to allow for control over the product distribution. Furthermore, the reaction of (BDI)Me2Nb(NCMe3) with XylNC (Xyl = 2,6-Me2C6H3) yields the η2-ketimine complex (BDI)(Me2C=NXyl)Nb(NCMe3), whose characterization and reactivity enhance our understanding of the sequences involving CO. Copyright
