Strong oxidants such as chlorine rad-ical anions' and mORochlorocobalt(III) ions are generated by flash photolysis. Oxidation of nickel(IIrand copper (II) tetraazamacrocyclic com­plexes are reported. The nickel(III) and copper(III) complexes are stable in st·rongly acidic aqueous solutions. Axial coordination of chloride stabilizes the copper(IlI) state of copper mac­rocyclic complexes; while nickel(III) state are stabilized at low chloride ion consentration. Thus, an outer-sphere electron- transfer mechanism was propose

M A KHALIFA ,