Mechanism of oxidation of (olefin)Rh-I and -Ir-I complexes by H2O2

Abstract

A DFT study of the oxidation of (tpa)M-I(C2H4)(+) and (dpa-R)M-I(cod)(+) complexes (M = Rh, Ir) by H2O2 indicates that the reaction starts with heterolytic cleavage of the peroxide O-O bond, leading to M-III(olefin)(OH)(2+) species. These can then undergo cyclisation, followed by deprotonation to oxetanes. In the oxidation of COD complexes, further cyclisation to internal ethers has a modest barrier, and the observed products (ethers for Rh, oxetanes for Ir) are suggested to be the thermodynamic ones. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004.