Electro-vibrational Ising-type model for spin crossover in binuclear molecules

Abstract

A spin crossover in binuclear molecule is investigated using an Ising-type model, including the intramolecular vibrations. The spin transition curve of [Fe(bt)(NCS)2]2bpym complex which presents a two-step transition plateau is well described by the above model. We show that the equilibrium low-spin/high-spin temperature $$ T_{\text{eq}} $$ is independent of the vibration frequencies of the intermediate state (HS–LS or LS–HS) $$ \omega_{\text{LHS}} $$ . In addition, a large values of LS–LS state vibration frequencies $$ \omega_{\text{LLS}} $$ lead to an evident two-step transition plateau.