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

The reactions of VVO(O-iPr)3 with [PS3′]H3 and [PS3]H3 {[PS3′]H3 = P(C6H3-5-Me-2-SH)3, [PS3]H3 = P(C6H4-2-SH)3} led to the formation of [VIV(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 VVO(O-iPr)3 with [PS3′]H3 was conducted in the presence of methoxide followed by the addition of a cation, [VIV(PS3′)(PS2SMe′)]X [X = N(C2H5)4 (2a), N(C2H5)3(CH2Ph) (2b)] was isolated, where PS2SMe′ 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. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)