CO(II)-INDUCED RADICAL OXIDATIONS BY PEROXOMOLYBDENUM COMPLEXES

Peroxomolybdenum complexes, which are usually rather stable materials both in the solid state and in solution, may undergo a decomposition r eaction yielding dioxygen when relatively small amounts of Co(acac)2 a re added to their solution in dichloroethane. Such a reaction is great ly dependent on the nature of the coordination sphere of the metal. In the series of neutral and anionic peroxomolybdenum species examined, the anionic complex MoO5PICO (PICO = picolinate N-oxido anion) has bee n found to be more prone to decompose than the neutral ones. By contra st, electrochemical measurements indicate that the one-electron reduct ion of the neutral species occurs at less negative potentials than tha t of the anionic ones. Under the conditions which allow the decomposit ion of MoO5PICO, the concomitant oxidation of organic substrates, e.g. alkanes and alkenes, takes place. The product analyses confirm that t he peroxomolybdenum complex is acting as a radical oxidant. The role o f Co(II) not only in promoting the decomposition but also in taking pa rt in a radical process is suggested by kinetic and electrochemical ex periments.