Resonance Raman spectra of highly reduced iron porphycenes

The redox behavior of iron porphycenes using the sodium mirror contact technique is reported. The resonance Raman spectra are obtained for each redox state, in order to explore the vibrational characteristics of these species in different redox states. The observed resonance Raman behavior of Fe II porphycene anion radical and its dianion is interpreted using the vibrational analysis of free-base porphycene anion radical and dianion. For the first time, a species generated in the fourth reduction step, is confirmed by UV-vis spectroscopy and is assigned to Fe I porphycene π dianion. The dependence of resonance enhancements of Raman bands for the Fe I porphycene π dianion on excitation laser reveals structural distortion along the NC a C a N or C b C a C a C b segments of the pyrrole-pyrrole direct connection in the excited electronic state.