Cationic complexes of iridium. Part II. Kinetic studies on the reductive elimination of hydrogen from [IrH2(CO)2L2]BPh4(L = tertiary phosphine or tertiary arsine)
The complex [IrH2(CO)2L2]BPh4(L = tertiary phosphine or arsine) reacts with CO, P(OMe)3, P(OPh)3, or PMePh2(L′) at a rate which depends only on the concentration of the complex and is independent of the nature or concentration (over the range studied) of the substituting ligand, L′. This is explained in terms of a rate-determining step involving reductive elimination of H2 from the complex to give a four-co-ordinate intermediate which then reacts rapidly with L′. The dependence of the rate of the reaction on the nature of L has been studied and is discussed.