PHOTOCHEMICAL REDUCTION AND OXIDATION OF CERIUM(IV) PORPHYRIN SANDWICH COMPLEXES

Irradiation of cerium(IV) complex of octaethyl bisporphyrin Ce[OEP(-2] (2) with visible light, in the presence of CCl4 as an electron accepto r, leads to their photooxidation and pi cation radical formation. The process was followed using electron absorption and magnetic circular d ichroism spectroscopy. Electronic configuration in neutral mono- and b isporphyrin (sandwich) complexes were compared to the one of the neutr al species. Photoirradiation of sandwich octaethyl- and tetraphenyl bi sporphyrins, in the presence of an electron donor (triethylamine) resu lts in their photoreduction on different pathways. Formation of the [C e(III)(TPP)(-2)TPP(-2)](-) and [Ce(III)(OEP)(-1)(OEP)(-2)] complexes w as followed by absorption and electron spin resonance spectroscopy.