KINETICS AND MECHANISM OF OXIDATION OF COBALT(II) MACROCYCLES BY IODINE, BROMINE, AND HYDROGEN-PEROXIDE

A series of cobalt(II) complexes of tetradehtate, 14-membered macrocyclic ligands with nitrogen donor atoms is oxidized by bromine and iodine in acidic aqueous solution to the corresponding monohalocobalt(III) product. The rate law shows a first-order dependence on each reactant; rate constants and reduction potentials were determined for each substance. Only one of the cobalt(II) complexes, CoII([14]aneN4)2+, reacts with hydrogen peroxide in the same manner, and in that reaction positive results were obtained in scavenging for a hydroxyl radical intermediate. The other peroxide reactions apparently do not produce HO. The mechanisms of all of the reactions are considered and discussed. © 1979, American Chemical Society. All rights reserved.