Evolution of the spin state of a 3d ion in a pyramidal complex

Abstract

The evolution of the spin state of a metallic 3d ion in a pyramidal MeO5 environment is studied. Ions of metals with 3d6 (Fe2+,Co3+) and 3d4 configurations (Mn3+,Cr2+) are studied. The change in the spin state of the metal ion from S=0 to S=1 and S=2 with a variation of the effective charge Zeff of the metal ion and the displacements of the oxygen ions is investigated. The stability of the spin state as a function of the magnitude and symmetry of the displacements of the ligands is checked. Breathing-mode distortions, displacements of the 3d ion along the Z axis, Jahn-Teller distortions of the basal plane of the pyramid, and fluting distortions of the plane of the pyramid are studied. It is shown that different types of distortions produce different behaviors of the terms corresponding to a change in the spin states of all three types. It is found that the spin state of the coordination complex MeO5 with the 3d4 configuration of the metal ion is most sensitive to breathing-mode distortions and Jahn-Teller type distortions stabilize the state with spin S=1 for the 3d6 configuration.