Heteroligand o‑Semiquinonato-Formazanato Cobalt Complexes

Two novel heteroligand o-semiquinonato-formazanato cobalt complexes [Co­(3,6-SQ)­(Form)] (1) and [Co­(3,6-SQ)2(Form)] (2) (3,6-SQ is 3,6-di-tert-butyl-o-benzosemiquinonate radical anion; Form is 1,3,5-triphenylformazanate anion) were synthesized and characterized in detail. The molecular structures of [Co­(3,6-SQ)­(Form)] and [Co­(3,6-SQ)2(Form)] were determined by X-ray analysis. Magnetic susceptibility measurements and spectroscopic studies have shown that square-planar complex 1 is diamagnetic with a residual paramagnetism due to antiferromagnetic exchange metal–ligand. Complex 2 includes cobalt­(III) in the low-spin state and two anionic-radical o-semiquinonato and one formazanate ligand.