OXIDATION REACTIONS OF [(ME3SI)(2)N](2)VX(THF) (X=CL, ME, PH) WITH CUCL, PHCH(O)CH2, AND PH2CN2 AND THE SYNTHESES AND STRUCTURES OF THE VANADIUM(III) ANIONS ([(ME3SI)(2)N](2)VX2)(-) (X=CL, ME)

One-electron oxidation of [(Me3Si)(2)N](2)VX(THF) (X = Cl, Me, Ph) wit h Cucl afforded the V(IV), d(1) species [(Me3Si)(2)N](2)VCl(X) in mode rate yields after crystallization from acetonitrile. [(Me3Si)(2)N](2)V Cl2 has been characterized crystallographically. The methyl and phenyl derivatives were conveniently synthesized, in one step from [(Me3Si)( 2)N](2)VCl(THF) by first reacting first with LiMe or MgPh2, prior to t reatment with CuCl. Reaction of [(Me3Si)(2)N](2)VCl(THF) with dilithio acetylide in the presence of tetramethylethylenediamine (TMEDA) procee ded with redistribution of the Cl ligands, as the anionic V(III) compo und [Li(TMEDA)(2)]{[(Me3Si)(2)N](2)VCl2} was obtained in 44% yield as purple crystals. The analogous dimethyl anion [Li(TMEDA)(2)]{[(Me3Si)( 2)N](2)VMe2} was synthesized in 66% yield as deep-blue, highly air-sen sitive crystals on treatment of [(Me3Si)(2)N](2)VCl(THF) with 2 equiv of LiMe in the presence of TMEDA. X-ray crystallography showed that bo th salts crystallized as well-separated cations and anions. The reacti on between styrene oxide slid [(Me3Si)(2)N](2)VMe(THF) proceeded stepw ise, first yielding the mu-O intermediate {[(Me3Si)(2)N](2)VMe}(2)(mu- O) and then the V(V) terminal oxo [(Me3Si)(2)N](2)V(O)(Me). Styrene ox ide also oxidized [(Me3Si)(2)N](2)VPh(THF) to [(Me3Si)(2)N](2)V(O)(Ph) , however, in this case the putative mu-O intermediate could not be is olated as a stable material. Diphenyldiazomethane was reduced by two e lectrons to an alkylidenehydrazido(2(-)) on displacing THF from [(Me3S i)(2)N](2)VCl(THF) to form the V(V) complex [(Me3Si)(2)N](2)V(Cl)(N2CP h2). A crystal structure showed the diazoalkane to be coordinated in a doubly-bent fashion.