Ambidenticity of a tridentate oxygen-nitrogen donor towards bivalent and trivalent transition metal ions

Summary N-salicylidene anthranilamide (H₂SAA) and its Cr^III, Mn^II, Fe^III, Co^II, Ni^II and Cu^II complexes were prepared and characterized by physicochemical and spectroscopic data. H₂SAA enolizes to give a dibasic ONO donor set in the divalent metal complexes. It also binds to the trivalent metal ions in a nonenolized form using a monobasic ONN donor set. Co^II is oxidized to Co^III during complexation. Octahedral geometries are proposed for Cr^III, Mn^II, Fe^III and Co^III complexes, while square planar geometries are suggested for the Ni^II and Cu^II complexes. Phenoxide bridging in the Cr^III and Fe^III complexes and enoxide bridging in the Ni^II and Cu^II complexes is proposed.