The role of CO2 in metal-catalyzed peroxidations

Abstract Transition metals, such as Cu +2 , Mn +2 , and Co +2 , have been seen to catalyze the bicarbonate enhanced oxidation of a variety of substrates by H 2 O 2 . In several of these cases it has been demonstrated that CO 2 , rather than bicarbonate, is the enhancing species. Mechanisms that are in accord with the data involve a hypervalent state that may be written (MO) + n , or (MOH) + n +1 , or (M) + n +2 . This metal centered oxidant then oxidizes CO 2 to the carbonate radical; that is then the proximal oxidant of the various substrates. Whether a similar process has in vivo reality remains to be demonstrated.