Unusual structural features in tetrabromocatechol-chelated dinuclear manganese(III) complex: Synthesis, electrochemistry and thermally induced valence tautomerism

A novel dinuclear manganese(III) complex derived from tetrabromocatechol is reported. X-ray crystal structure reveals a bipyrimidine-bridged dinuclear manganese(III) complex in which both the metal ions are situated on the crystallographic inversion center. The most important feature of the crystal structure is that the geometrically rigid bidentate tetrabromocatechol ligand stretches one arm to coordinate axially elongated position. Moreover, the complex was found to exhibit thermally induced valence tautomerism accompanied by optical absorption spectral changes. As far as I am aware this is the first structural characterization of a dinuclear manganese(III) complex that consists exclusively of rigid bidentate ligands.