Magnetic Property and Electronic Structure of Tris(2,2′-bipyridine) Complexes of Manganese in Low Oxidation States

The magnetic susceptibilities of tris(2,2′-bipyridine)manganese complexes, [Mn(bpy)3]·2THF and Li[Mn(bpy)3]·4THF (THF: tetrahydrofuran), have been determined over a temperature range of 1.6–320 K. The susceptibility of Li[Mn(bpy)3]·4THF can be explained with a radical ion model, in which three 2,2′-bipyridine radical ions are coordinated to a manganese(II) ion. A similar model is applicable to [Mn(bpy)3]·2THF as well. The presence of antiferromagnetic interaction indicates the formation of a weak covalent bond between manganese and bipyridine. This can be elucidated consistently by the molecular orbital theory.