ELECTRON-TRANSFER IN TETRANUCLEAR MIXED-VALENCE IRON CLUSTERS - ROLE OF THE TOPOLOGY ON THE MAGNETIC-PROPERTIES

The energy levels and magnetic properties of mixed-valence d5d5d5d6 clusters are studied from a model that takes into account the electron transfers between orbitally nondegenerate orbitals of the metal ions, and superexchange interactions. The influence of the electron transfer on the spin state energies and magnetic properties is examined as a function of the geometry of the tetra-nuclear cluster, including the limiting cases with T(d) and D4h symmetries. For geometries close to the tetrahedral, effects of anti-ferromagnetic superexchange interactions are also discussed.