Heterobimetallic S,S-bridged complexes, [S2MS2M'I-2](2-) (M=Mo, W; M'=Cd-II, Hg-II, Zn-II): Synthesis, structure and redox properties

Heterobinuclear complexes, [S2MS2M'I-2](2-) (M = Mo, W; M' = Cd, Hg, Zn), have been synthesized as PPh4- salts by reacting [M'I-4](2-) with [MS4](2-). The complexes are characterized by nu (metal-sulphur) terminal, nu (metal-sulphur) bridging and nu (metal-iodine) terminal vibrations in their IR spectra. The single-crystal X-ray structure analysis of (PPh4)(2)[S2WS2CdI2] (1) reveals a two-fold anionic disorder. The coordination geometries about the metal centers in the anions [S2WS2CdI2](2-), containing planar [WS2Cd] cores, are best described as distorted edge-shared bitetrahedra. The oxidation states of cadmium and tungsten in a sulfur environment in 1 have been confirmed by X-ray photoelectron spectroscopy. Zn-II and Cd-II complexes each show a single metal centered irreversible cyclic voltammetric response essentially localised within [MS4](2) ligands. (C) 1997 Elsevier Science Ltd.