Mixed Valence Iron Dimer in the Generalized Vibronic Model: Optical and Magnetic Properties

Abstract

A mixed valence iron dimer $[{\mathrm{L}}^{1}{\mathrm{Fe}}_{2}{(\mu -\mathrm{OAc})}_{2}]({\mathrm{ClO}}_{4})$ is investigated in the framework of the generalized vibronic model which takes into account both the local vibrations on the metal sites (Piepho-Krausz-Schatz model) and the molecular vibrations changing the intermetallic distance (suggested by Piepho). It is shown that the behaviour of the system is determined by a strong competition between three main processes: double exchange interaction and vibronic coupling with both types of vibrations. The optical and magnetic properties of the regarded compound are reported. The influence of the key parameters of the system on these properties is studied in the framework of the presented theoretical model. The degree of delocalization of the itinerant ‘extra’ electron and probability distribution in configuration (qQ) space are calculated at different values of temperature.