Redox chemistry in the reaction of oxovanadium(V) with thiolate-containing ligands: The isolation and characterization of non-oxo vanadium(IV) complexes containing bisulfide and thioether groups

The reactions of V^VO(O-iPr)₃ with [PSS′]H ₃ and [PS3]H₃ |[PS3′]H₃ = P(C ₆H₃-5-Me-2-SH)₃, [PSS]H₃ = P(C ₆H₄-2-SH)₃} led to the formation of [V ^IV(L)] [L = P2S4′ (1a), P2S4 (1b)], where L was formed by the oxidative coupling of two PS3′ or PS3 ligands by a disulfide bond. When the reaction of V_VO(O-iPr)₃ with [PS3′]H₃ was conducted in the presence of methoxide followed by the addition of a cation, [V^IV(PS3′)-(PS2S^Me′)]X [X = N(C ₂H₅)₄ (2a), N(C₂H₅) ₃(CH₂Ph) (2b)] was isolated, where PS2S ^Me′ is a bis(benzenethiolato)phenylmethylthioetherphosphane ligand generated from the methylation of one thiolate group in PS3′. The structures of complexes 1a,b and 2a,b, determined by X-ray crystallography, contain six- and seven-coordinate non-oxo vanadium(IV) centers, respectively, with an octahedral geometry for 1a,b and a pentagonal-bipyramidal geometry for 2a,b. The electronic, magnetic, and electrochemical properties of these complexes were determined by UV/Vis and EPR spectroscopy, SQUID measurements, and cyclic voltammetry.