RESONANCE RAMAN-SPECTROSCOPIC CHARACTERIZATION OF THE PI-ANION AND PI-CATION RADICALS OF ZINC(II) OCTAETHYLCHLORIN

Cyclic voltammetry (CV), UV-vis spectroscopy, and resonance Raman (RR) spectroscopy are utilized to characterize the pi-anion and pi-cation radicals of ZnOEC (OEC octaethylchlorin). Features in the RR spectra a re assigned with the aid of data from the meso-d(4) isotopomer of ZnOE C and ZnEtI (EtI = etiochlorin I). The vibrational frequency shift pat terns of the radicals ate consistent with expected bonding changes on placing an electron in the LUMO or a hole in the HOMO. The frontier or bitals are similar in ZnOEC and ZnOEP (OEP octaethylporphyrin), but th e anion spectra differ because of the consequences of the Jahn-Teller effect in ZnOEP-. The cation and anion vibrational shifts do not add t o give the shifts previously reported for the triplet state, indicatin g additional distortion upon triplet excitation.