Bis-o-semiquinonato complexes of transition metals with 5,7-di-tert-butyl-2-(pyridine-2-yl)benzoxazole

New cobalt(II) (I), iron(II) (2) and manganese(II) (3) complexes of M(3,6-SQ)(2)L type containing 3,6-di-tert-butyl-o-benzosemiquinonato ligands (3,6-SQ) and 5,7-di-tert-butyl-2-(pyridine-2-yl)benzoxazole (L) were synthesized and characterized in details. Magnetic susceptibility measurements and spectroscopic studies have shown that all complexes include metal(II) in the high-spin state and two radical-anionic o-semiquinonato ligands. The antiferromagnetic ligand-ligand coupling in cobalt(II) and iron(II) complexes takes place, while manganese(II) complex demonstrates metal-ligand antiferromagnetic interactions. Molecular structure of Co(3,6-SQ)(2)L was determined by X-ray analysis. Cobalt(II) atom has a distorted trigonal prismatic environment. (C) 2012 Elsevier Ltd. All rights reserved.