Cationic complexes of iridium. Part III. Some thiocarbonyl complexes

Abstract

New five-co-ordinate thiocarbonyl complexes [Ir(CO)₂(CS)L₂]X (L = PPh₃ or PCy₃, Cy = cyclohexyl; X = BPh₄ or ClO₄), [Ir(CO)(CS)(PMePh₂)₃]BPh₄, [Ir(CS)(diphos)₂]BPh₄, and [IrCl(NO)(CS)L₂]BF₄ are reported. These complexes have been synthesised from trans-IrCl(CS)L₂, by routes similar to those used in the preparation of their carbonyl analogues, with which they are compared and contrasted. [Ir(CO)₂(CS)(PPh₃)₂]ClO₄ does not react with hydrogen in solution, while [Ir(CO)₂(CS)(PCy₃)₂]ClO₄ reacts to give the dihydride [IrH₂(CO)(CS)(PCy₃)₂]ClO₄. Passage of CO through a solution of the latter, regenerates the original pentaco-ordinated iridium(I) complex, and the lability of the co-ordinated hydrogen is confirmed by its ready exchange with deuterium, to give the dideuteride. The reaction of [Ir(CO)₂(CS)(PPh₃)₂]ClO₄ with methoxide ion proceeds by nucleophilic attack at a carbonyl group, rather than at the thiocarbonyl group, to give Ir(CO₂Me)(CO)(CS)(PPh₃)₂.