Hard molecule-based magnet of Fe

A new molecule-based magnet containing Fe 2+ , Fe 3+ , Cu(opba) 2- and Bu 4 N + , with opba = ortho-phenyle-nebis(oxamato) and Bu 4 N + = tetra-n-butylammonium, was synthesized. The samples were characterized by infrared spectroscopy, elemental analysis, atomic absorption, vibrating sample magnetometry and 57 Fe Mossbauer spectroscopy. The magnetic measurements show that the compound presents a magnetic transition around 25 K and a high coercivity, around 1.3 T. Above the transition temperature, the Mossbauer spectrum is dominated by a broad doublet characteristic of Fe 2+ , At 20 K, the spectrum shows clear magnetic splitting and at least two non-equivalent Fe sites can be identified. To the best of our knowledge, this compound presents the highest coercive field observed for an iron-based molecular magnetic system.