Complexes of the platinum metals. Part VI. Dithiocarbamato- and O-alkyl dithiocarbonato-derivatives of ruthenium, osmium, and iridium

New dithiocarbamato- and O-alkyl dithiocarbonato-derivatives, [M(S–S)2(PPh3)2], [M(S–S)2(CO)(PPh3)], [MH(S–S)(CO)(PPh3)2](M = Ru or Os; S–S = R2NCS2– or ROCS2–; R = Me or Et), [OsCl(S2CNR2)(CO)(PPh3)2], and [IrH2(S–S)(PPh3)2], have been prepared by treating the appropriate chloro- orcarboxylato-complexes with sodium salts of the ligand. In several instances, hydride ligands, present in the parent complex, are also replaced by S–S groups. Tetramethylthiuram disulphide reacts with [IrCl(CO)(PPh3)2], [RuH2(PPh3)4], and [RuH2(CO)(PPh3)3] or [RuHCl(CO)(PPh3)3] to afford the complexes [Ir(S2CNMe2)2(CO)(PPh3)]Cl, [Ru(S2-CNMe2)2(PPh3)2], and [Ru(S2CNMe2)2(CO)(PPh3)] respectively. Structural and stereochemical assignments based on n.m.r. and i.r. spectroscopic data for the R2NCS2– and ROCS2– complexes confirm the expected substantial barrier to rotation about the S2C–NR2 bond in the former, but reveal no evidence of a comparable barrier to rotation about the S2C–OR bond in the latter.