Addition of Si-H and B-H Bonds and Redox Reactivity Involving Low-Coordinate Nitrido-Vanadium Complexes

Abstract

In this study we enumerate the reactivity for two molecular vanadium nitrido complexes of anatnac)V equivalent to N(X)] formulation [nacnac = (Ar)NC(Me)CHC(Me)(Ar)(-), Ar = 2,6-(CHMe2)(2)C6H3); X- = OAr (1) and N(4-Me-C6H4)(2) (Ntolyl(2)) (2)]. Density functional theory calculations and reactivity studies indicate the nitride motif to have nudeophilic character, but where the nitrogen atom can serve as a conduit for electron transfer, thus allowing the reduction of the vanadium(V) metal ion with concurrent oxidation of the incoming substrate. Silane, H2SiPh2, readily converts the nitride ligand in 1 into a primary Silyl amide functionality with concomitant two-electron reduction at the vanadium center to form the complex [(nacnac)V{N(H)SiHPh2}(OAr)] (3). Likewise, addition of the B-H bond in pinacolborane to the nitride moiety in 2 results in formation of the boryl amide complex [(nacnac)V{N(H)B(pinacol)}(Ntolyl(2))] (4). In addition to spectroscopic data, complexes 3 and 4 were also elucidated structurally by single-crystal X-ray diffraction analysis. One-electron reduction of 1 With 0.5% Na/Hg on a preparative scale allowed for the isolation and structural determination of an asymmetric bimolecular nitride radical anion complex having formula [Na](2)[(nacnac)V(N)(OAr)](2) (5), in addition to room-temperature solution X-band electron paramagnetic resonance spectroscopic studies.