KINETICS OF AUTOXIDATION OF COBALT(II) CYCLIDENE DIOXYGEN CARRIERS

The cobalt(II) cyclidene complexes are known to bind dioxygen reversibly under ambient conditions; however, the lifetime of the dioxygen adduct is limited by autoxidation. This paper describes a study of the autoxidation reactions of the cobalt(II) cyclidenes in nonaqueous media. The kinetics of the autoxidation reaction of the cobalt(II)complex are dependent on the nature of the ligand substituents and dioxygen concentration and on the nature and concentration of added base. Mechanistic details have been explored through isotopic substitution of the ligand. The proposed mechanism involves preequilibrium deprotonation of the ligand in the dioxygen complex, followed by irreversible ligand oxidation.