Magnetic field dependent phase transition in a Fe - Cr based molecular magnet

We have recently prepared a Fe - Cr based dimer where metal ions are bridged by a redox active dhbq ligand. Variable temperature magnetic susceptibility shows the molecule exhibits a temperature-induced spin-crossover / valence-tautomeric type transition. We find the transition can additionally be controlled by an external magnetic field. A magnetic field controllable phase transition is very unusual for molecular-based systems. We require Fe and Cr K-edge XANES measurements as a function of temperature and magnetic field to track the spin ground state and oxidation state of Cr and Fe sites to confirm the origin phase transition. To link the observed changes in magnetism and electronic structure to geometric structure we require Fe and Cr EXAFS measurements. The results will provide the Cr and Fe spin-states and structures that will feed density functional theory calculations and obtain a detailed insight into nature of the phase transition.