Quantum chemical analysis of the electronic structure and Mössbauer spectra parameters for low spin cyanide—and pyridine—hemichromes

The work contains results of quantum chemical calculations of electronic structure and Mossbauer spectra parameters for low spin S=1/2 hexa-coordinated ferri-porphyrin complexes with cyanide (CN) and pyridine (Py) as axial ligands. Theoretical results made it possible to explain experimentaly observed regularity of anomalous quadrupole splitting decrease after substitution of Py-ligands by CN. Comparison of theoretical and experimental data indicated that2Eg must be the ground state of investigated hemichromes. In this state unpaired electron symmetrically occupies dπ-orbitals of Fe-ion.