Photolysis of a Cobalt(III) complex with a tetradentate macrocyclic (N4 ligand. Photoredox reaction

Abstract

The photolysis of CO(Me4[14]tetraeneN4)(OH2)3+ 2 in an aqueous acidic medium has been carried out with incident wavelengths at 254, 265, 313 and 365 nm. Spectrophotometric measurements in the uv, visible, ir and nmr region show that reduction of the metal centre takes place, but the macrocyclic ligand remains intact. The quantum yield of CoII (N4) formation is small and decreases with decreasing photon energy. Addition of alcohol leads to an appreciable increase in the quantum yield, and the effect of glycerol is comparable to that shown by 2-propanol or t-butanol. The results are interpreted within the context of the radical-pair model with formation of hydroxyl radicals. © 1982.