STUDIES ON THE COORDINATED DIOXYGEN SPECIES PRODUCED FROM THE PHOTOPRODUCTS OF ALKYLCOBALOXIMES IN AQUEOUS-SOLUTION

The reactions of molecular oxygen with photoproduced cobaloximes(II) f rom the cobalt(III) complexes [CH3Co(DH)(2)Py], 1 and [C2H5Co(DH)(2)Py ], 2 (where DH is dimethylglyoxime and py is pyridine) have been inves tigated by flash photolysis methods. The reaction of cobaloxime(II) wi th molecular oxygen to give mononuclear superoxocobalt(III) species is the first step. The reactions to form the mu-superoxo cobalt(III) com plex from the mononuclear superoxo complex and the alkyl cobalamine(II I), and the formation of the mu-peroxo cobalt(III) complex directly by the reaction between mononuclear superoxo complex and the photoproduc ed cobalamin(II) and by the 'conversion of mu-superoxo complex are the subsequent processes observed. The rate constants determined for thes e reactions are discussed based on a scheme indicating all the reactio ns. The results show that the reaction between the mononuclear superox o complex and the photoproduced cobalamin td give the mu-peroxo comple x is faster than the reaction involving formation of the mu-superoxo c omplex from the mononuclear superoxo complex.