Oxidative substitution reaction of the osmochrome Os(OEP)[P(OMe) 3] 2 in chlorinated solvents

Abstract

Steady state photolysis of Os(OEP)[P(OMe) 3] 2, where OEP is octaethylporphine, in the chlorinated solvents CH 2Cl 2, CHCl 3 and CCl 4 at 365 and 405 nm and at 22 °C results in the formation of an osmium(IV) porphyrin identified as Os(OEP)Cl 2. The reaction is described as an oxidative substitution reaction. The rate of formation of the photolysis product increases as the solvent varies in the order CH 2Cl 2 < CHCl 3 < CCl 4 (in the ratio 1:8:120). The quantum yield of product formation is 0.004 and 1.4 in CH 2Cl 2 and CCl 4 respectively. A possible mechanism involving radicals is suggested and is discussed in terms of the experimental observations.