Ferromagnetic coupling between semiquinone type tridentate radical ligands mediated by metal ions

Studies on 3,5-di-tert-butylcatechol, aqueous ammonia and titanium, vanadium, germanium acid tin bis complexes of tridentate Schiff base biquinone ligand reveals the triplet ground states caused by intramolecular ferromagnetic interaction between two ligands. Specific radicals are required for ferromagnetic coupling between complexes. The complex is shown to be an admixture of vanadium and ligand orbitals.