π–d INTERACTION BASED MOLECULAR CONDUCTING MAGNETS: HOW TO INCREASE THE EFFECTS OF THE π–d INTERACTION

The crystal structures and electronic and magnetic properties of conducting molecular magnets developed by our group are reviewed from the viewpoints of our two current strategies for increasing the efficiency of the π–d interaction. (EDTDM)₂FeBr₄ is composed of quasi-one-dimensional donor sheets sandwiched between magnetic anion sheets. The ground state of the donor layer changes from the insulator state to the metallic state by the application of pressure. When it is near to the insulator-metal phase boundary pressure, the magnetic order of the anion spins considerably affects the transport properties of the donor layer. The crystal structure of (EDO–TTFBr₂)₂FeX₄ (X = Cl, Br) is characterized by strong intermolecular halogen-halogen contacts between the organic donor and FeX₄ anion molecules. The presence of the magnetic order of the Fe³⁺ spins and relatively high magnetic order transition temperature proves the role of the halogen-halogen contacts as exchange interaction paths.