SYNTHESIS OF N(SIME3)(2) SUPPORTED VANADIUM(III) COMPLEXES, INCLUDINGHYDROCARBYL, TETRAHYDROBORATE AND AZAALKENYLIDENE DERIVATIVES

Reaction of [(Me3Si)(2)N](2) VCl(THF) (THF = tetrahydrofuran) with MgM e2 or LiMe afforded [(Me3Si)(2)N](2)-VMe(THF) in 70% yield. Nitrogen d onors displaced THF in these V-III species, and [(Me3Si)(2)N](2)VCl(lu t) (lut = 3,5-dimethylpyridine) and [(Me3Si)(2)N](2)VMe(pyr) (pyr = py ridine) were isolated and characterized. Solution thermolysis of [(Me3 Si)(2)N](2)VMe(THF)yielded the known V-III dimer {[(Me3Si)(2)N] V(mu-C H2SiMe2-NSiMe3)}(2) in 73% yield. Reaction of [(Me3Si)(2)N](2)VMe(THF) with 3 equivalents of RNC (R = Bu-t or Xyl; Xyl = 2,6-dimethylphenyl) gave diazavanadacycles of empirical formulae [(Me3Si)(2)N](2)V[(Me)(C NR)(3)]. For R = Bu-t, the product [(Me3Si)(2)N](2)V[(BuN)-N-t=CMeC(=C =NBut)NBut] features an exocyclic keteneamine functionality; for R = X yl, an additional C-C bond forming step results in slightly more compl ex connectivity, to give )N](2)V[N(Xyl)CMe=C-C(=NXyl)CMeCH=CH-CH=CMeC( =N)]. The crystal structures of both compounds are presented. Alkylati on of [(Me3Si)(2)N](2)VCl(THF) with 2-thienyllithium led to isolation of [(Me3Si)(2)N](2)V(2-C4H3S)(THF) (60%). A blue solution that acted a s a source of '[(Me3Si)(2)N](2)VPh' was obtained from the reaction of 0.5 equivalent of MgPh2 with [(Me3Si)(2)N](2)VCl(THF). The addition of pyr or PhCN to the blue mixture gave [(Me3Si)(2)N](2)VPh(pyr) (60%) a nd [(Me3Si)(2)N](2)V(NCPh2)(NCPh) (66%), respectively. The chelated ar yl amine [(Me3Si)(2)N](2)V(o-Me2NCH2C6H4) was synthesized from [(Me3Si )(2)N](2)VCl(THF) and Li(o-Me2NCH2C6H4) in 81% yield. Treatment of [(M e3Si)(2)N](2)VCl(THF) with excess LiBH4 in the presence of pyr afforde d the vanadium tetrahydroborate [(Me3Si)(2)N](2)V(eta(2)-BH4)(THF) in 41% yield. The solid-state structures of [(Me3Si)(2)N](2)VPh(pyr), [(M e3Si)(2)N](2)V(NCPh2)(NCPh), [(Me3Si)(2)N](2)V(eta(2)-o-Me2NCH2C6H4) a nd [(Me3Si)(2)N](2)V(eta(2)-BH4)(pyr) are reported.