Local structure of Fe2+ and Fe3+ in organic solvents

We systematically investigated the local structure of Fe2+ and Fe3+ in 11 solvents by extended X-ray absorption fine structure (EXAFS) analysis and X-ray absorption near-edge structure (XANES). The EXAFS analyses with a one-shell model indicate that Fe2+ and Fe3+ are coordinated by six oxygen of the ligand molecules (L) and form a FeL (6)-type complex in all solvents. The XANES suggests that the [FeL (6)](3+) complex shows noncentrosymmetric deformation in several solvents. In protic solvents, the EXAFS analyses with a two-shell model revealed that the coordination number (n (C)) of the second nearest carbon around Fe3+ significantly depends on L. We interpreted the observation in terms of the distribution of the Fe-C distance.