Complex-forming properties of substituted N-hydroxyacetoacetanilides with bivalent and tervalent metal ions

From spectroscopic studies as well as from the stability constants of their complexes with metal ions, it has been observed that substituted N-hydroxyacetoacetanilides do not enolize, because of strong hydrogen bonding in the hydroxamic moiety CH(3).CO.CH(2).CO.N(OH).R hindering the movement of the CH(3).CO.CH(2)- group. The ligands thus behave as bidentate in contrast to the expected terdentate nature. The stability constants of their complexes are comparable with those for complexes of other ligands in which oxygen is the donor.