異常な電子状態を有するポルフィリン金属錯体の結晶構造

抄録

The crystal structures of porphinato-iron (III) complexes with an anomalous inter-mediate-spin state (S=3/2) were compared with those of high-and low-spin iron (III) porphyrins. The intermediate-spin state is arisen in an asymmetric coordination field around the central iron (III) ion with respect to the axial and equatorial ligand strengths, while both the low-and high-spin states have approximately octahedral fields. The axial iron ligand distance in the intermediate-spin state is significantly different from the equatorial distances. The geometric parameters consistent with the electron configuration of the intermediate-spin state.
The crystal structures of porphinato-ruthenium (IV) and osmium (IV) complexes as a model of peroxidase compound II were discussed also. The complexes consist of the μ-oxo dimer with the weak ligand (OH^-, Cl^- or OCH₃^-) . The quadrivalent metallopor-phyrin was stabilized by a strong ligand of O^2- with σ^- and π-bonding natures. The diamagnetism in these complexes was explained by the dπ-pπ-dπ interaction in the M^IV-O-M^IVbond.