HIGH-NUCLEARITY MIXED-VALENCE CLUSTERS, THEORETICAL APPROACHES

A general approach is developed in order to calculate the energy level s and magnetic properties of high nuclearity mixed valence clusters. T he approach considers all the relevant electronic processes, namely (i ) interelectronic Coulomb repulsion between the moving electrons, whic h depend on the different distributions of the electronic pairs over t he available metal sites; (ii) single and double electron transfer pro cesses, which promotes the electron delocalization; (iii) magnetic exc hange interactions. This approach is applied here to tetranuclear iron (II)-iron (III) clusters for symmetries comprised between tetrahedral and square planar.