Electron Delocalization in Dimeric Mixed-Valence Systems

Abstract

Mixed-valence (MV) transition metal clusters contain two or more metal ion centers in different oxidation states between which an itinerant extra electron can transfer. These kind of compounds are of great interest because of their unusual spectral and magnetic properties and the possibility to use these properties for studying the intramolecular electron transfer process in many biologically important systems [1, 2]. For instance, valence delocalized [Fe₂S₂]⁺ pairs where iron is in the formal oxidation state +2.5 were found in a variety of iron-sulfur clusters in ferredoxins. Because of this, a growing interest in the characterization, the modeling and in the theoretical description of such compounds exists [3–6]. MV dimers are very convenient systems for better understanding of the electron delocalization process because of the possibility to take into account all relevant interactions. In this contribution we briefly discuss some of these interactions and their influence on the properties of the dimeric MV compounds. As a final step the investigation of a MV iron dimer in the generalized vibronic model is presented.