Transition-metal complexes containing phosphorus ligands. Part VIII. Sulphur dioxide derivatives of rhodium, iridium, palladium, and platinum

Abstract

The palladium and platinum complexes, M(PPh3)4, react with sulphur dioxide under anaerobic conditions to afford dark purple air-sensitive derivatives, M(SO2)(PPh3)3; these products undergo aerobic oxidation to form sulphatocomplexes, M(SO4)(PPh3)2,H2O. The rhodium and iridium hydrides, M′H (CO)(PPh3)3, on treatment with sulphur dioxide yield the first sulphur dioxide–hydride derivatives, ‘M′H(SO2)(CO)(PPh3)2’. The anomalous spectroscopic features of these last-named complexes are tentatively interpreted in terms of a tautomeric equilibrium involving hydride migration between the central metal atom and the co-ordinated sulphur dioxide ligand.