ONE-ELECTRON REDUCTION OF N-21,N-22-BRIDGED PORPHYRIN HYDROPERCHLORATE TO A STABLE PHLORIN RADICAL BY 1-BENZYL-1,4-DIHYDRONICOTINAMIDE

N-21,N-22-(1,2-Diphenyletheno)-bridged octaethylporphyrin hydroperchlo rate underwent one-electron reduction to give a thermally stable phlor in radical when treated with l-benzyl-l,4-dihydronicotinamide(BNAH). B NAH reduced, in the presence of acid, the same porphyrin to a two-elec tron reduced product, 21,N-22-(1,2-diphenyletheno)octaethyl-15H-phlori n, in contrast to the NaBH4-reduction to -21,N-22-(1,2-diphenyletheno) octaethyl-5H-phlorin.