Reaction mechanisms of metal–metal-bonded carbonyls. Part 17. Reactions of octacarbonylbis(triphenyl phosphite)dimanganese(Mn–Mn)

Abstract

The kinetics have been studied of the reactions in decalin of the complex [{Mn(CO)₄[P(OPh)₃]}₂] with oxygen, carbon monoxide, triphenylphosphine, and triphenyl phosphite. The dependence of the rate of reaction with oxygen on the concentration of complex is characteristic of reversible homolytic fission of the Mn–Mn bond as the major primary reaction step. The half-order nature of the decomposition of the complex in the presence of free P(OPh)₃ supports this. A value of 151.0 ± 2.1 kJ mol^–1 is assigned to the activation enthalpy for homolytic fission, and the effect of the two phosphite substituents on the kinetic strength of the Mn–Mn bond is small in contrast to the effect of two triphenylphosphine substituents.