Quantum chemical approach to the assignment of iron-catecholate vibrations and isotopic substitution shifts

In this communication we report the use of quantum chemical model calculations to assign iron-catecholate vibrations and to get quantitative predictions of the isotopic shifts. This study will show how such a new approach may increase the potential of vibrational spectroscopy especially the resonance Raman technique, in studies of metalloproteins. Results show that the model compound [Fe(catecholate)]2-, even though it may underestimate the Fe-O bond, gives reasonable vibrational frequencies and predicts isotope shifts which are in good agreement with experimental data.