Theoretical spectroscopy of model-nonheme [Fe(IV)OL5]2+ complexes in their lowest triplet and quintet states using multireference ab initio and density functional theory methods

The structure, energies and spectroscopic properties of a simple [FeO(NH3)5]2+ model with ground states 3A2g and 5A1g (in approximate C4v symmetry) have been studied in some detail using density functional (DFT) and simplified correlated multireference ab initio methods. The results reveal similarities as well as some pronounced differences in the properties of the molecule in the two alternative spin states.