Reactions involving transition metals. Part VIII. Decomposition of hydroperoxides catalysed by iridium(I) and by rhodium(I) complexes

Abstract

The complexes IrCl(CO)(PPh₃)₂ and RhCl(PPh₃)₃ catalyse decomposition of the hydroperoxides PhMe₂C·OOH and Me₃C·OOH to oxygen and the corresponding alcohols. Decomposition of Me₃C·OOH by IrCl(CO)(PPh₃)₂ is completely inhibited by phenol present in a molar ratio of phenol : iridium(I) complex of 5 : 1. 2,6-Di-t-butyl-p-cresol causes an induction period, the length of which varies with the cresol concentration, but thereafter the rate of decomposition is equivalent to that observed in the absence of inhibitor. Low concentrations of pyridine also inhibit this reaction, while similar concentrations of anisole and 2,6-lutidine are ineffective. The results are discussed in terms of a homolytic decomposition pathway in which co-ordination of the hydroperoxide to the metal atom is an important first step.