REDOX PROPERTIES OF CATIONIC VANADIUM(IV) - [CP(2)VCH(3)(CH3CN)][BPH(4)]

The cationic vanadium complexes [Cp(2)VCH(3)(CH3CN)](+) and [Cp(2)V(THF)](+) with [BPh(4)](-) as counterion are obtained from Cp(2)VMe(2) and [NHMe(2)Ph]BPh(4) in CH3CN or THF, respectively; in CH2Cl2, chloride abstraction from the solvent occurs via a redox decomposition, evidenced by the X-ray crystal structure of [N(CH2Cl)Me(2)Ph]BPh(4) and the formation of Cp(2)VCl. In presence of the phosphine PMe(2)Ph, [Cp(2)VCH(3)(CH3CN)](+) affords the intermediate species [Cp(2)VCH(3)(PMe(2)Ph)](+) (characterized by the EPR spectrum with resolved methyl hyperfine interaction) followed by a disproportionation and a redox reaction with [BPh(4)](-), giving Cp(2)VMe(2) and [Cp(2)V(PMe(2)Ph)](+). Preliminary studies show that [Cp(2)VCH(3)](+) is unreactive toward ethylene polymerization.