Complexes of aminophosphonates. Part 7. Copper(II) complexes of some aliphatic, alicyclic and aromatic aminophosphonous and aminophosphinic acids

Abstract

pH-Metric and spectroscopic (visible and ESR) studies were made of the proton and copper(II) complexes of various bidentate aliphatic, alicyclic and aromatic aminophosphonous and amino-phosphinic acids, and of the α- and β-phosphinic acid derivatives of aspartic acid, at 25 °C and at an ionic strength of 0.20 mol dm–3(KCl). It was found that the metal-binding abilities of these bidentate ligands are weaker than those of their aminocarboxylate analogues, which is due mainly to the differences in basicity of the PO2R– and the CO2– groups. The potentially terdentate aspartic acid derivatives are co-ordinated mainly via their aminocarboxylate moieties and the participation of the phosphinate group in the co-ordination is significant only for the α-phosphinic acid derivative. The metal-binding abilities of amino-phosphonates, -phosphinates and -carboxylates are compared.