Oxidation and reduction chemistry of bis(η-arene)niobium compounds; the X-ray crystal structure of bis(η-toluene)(trimethylphosphine)niobium tetrafluoroborate

Abstract

Cyclic voltammetry shows that [Nb(η-C₆H₅Me)₂] undergoes both one-electron reversible reduction and oxidation; chemical oxidation with AgBF₄ in the presence of PR₃(R = Me, R₃= Me₂Ph) yields [Nb(η-C₆H₅Me)₂(PR₃)]BF₄. The X-ray crystal structure of [Nb(η-C₆H₅Me)₂(PMe₃)]BF₄ has been determined and shows the molecule to have the bent bis(η-arene) structure. Reduction of [Nb(η-C₆H₃Me₃-2,4,6)₂] with potassium and treatment with carbon monoxide yields [Nb(CO)₆]^–; reduction in the presence of 18-crown-6 (1,4,7,10,13,16-hexaoxacyclo-octadecane,L) gives [KL][Nb(η-C₆H₃Me₃-2,4,6)₂].