The reactions of sulphur dioxide with the coordinatively unsaturated complexes [MCl(C6H4Me-4)(CO)(PPH3)2] (M = Ru, Os), and the role of the adduct [OsCl(C6H4Me-4)(CO)(PPh3)2(SO2)]

Article abstract of DOI:10.1016/0022-328X(88)83069-9

The 16-electron p-tolyl complexes [MCl(C₆H₄Me-4)(CO)(PPh₃)₂] (M = Os (1a), Ru (1b)) react with liquid sulphur dioxide, SO₂, to give the adduct [OsCl(C₆H₄Me-4)(CO)(PPh₃)₂(SO₂)] (2a) and the S-sulphinate complex [RuCl₂{S(O)₂C₆H₄Me-4)}(CO)(PPh₃)₂] (3b) respectively. The adduct 2a slowly undergoes conversion in solution into the S-sulphinate [OsCl{S(O)₂C₆H₄Me-4)}(CO)(PPh₃)₂] (3a), a process which is retarded by high concentrations of SO₂. The S-sulphinate complexes 3 react with carbon monoxide to give the O-sulphinates [MCl{OS(O)C₆H₄Me-4)}(CO)₂(PPh₃)₂] (M = Os (5a), Ru (5b)). It is suggested that the formation of 2a represents a diversion rather than an intermediate in the insertion process leading to 3a.