A b i n i t i o RHF and CASSCF studies on Fe–O bond in high-valent iron-oxo-porphyrins
- 1 January 1988
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 88 (1) , 303-312
- https://doi.org/10.1063/1.454655
Abstract
The electronic structure of the Fe–O bond in highly oxidized iron porphyrins was elucidated by ab initio RHF (restricted Hartree–Fock) and CASSCF (complete active space SCF) calculations on a neutral complex FeP(py)O (P=porphine, py=pyridine), which is a model of peroxidase compound II. Accounting for the correlation effects is essential for the description of the Fe–O bond. Equilibrium distance and stretching frequency of Fe–O were calculated from the potential energy curves obtained by CASSCF. Furthermore, Mössbauer spectrum parameters (quadrupole splitting, isomer shift, asymmetry parameter and direction of the principal axis of the electric field gradient tensor) and spin density were evaluated. They are in good agreement with experiments on the whole. The oxidation number of iron in peroxidase compound II was assigned to IV through an analysis of the CASSCF wave function.Keywords
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