Complexes of aminophosphonates. Part 8. Copper(II) complexes of N-(phosphonomethyl)amino acids and related compounds

Abstract

pH-Metric and spectroscopic (absorption and EPR) studies were made of the proton and copper(II) complexes of a series of ambidentate N-(phosphonomethyl)amino acids which contain both iminocarboxylate and iminophosphonate moieties. The stoichiometries and stability constants of the complexes formed were determined at 25°C and at an ionic strength of 0.20 mol dm^–3(KCl). Stability data and spectroscopic measurements revealed that the first ligand molecule co-ordinates very strongly, forming a tridentate equimolar species, while the second one binds to the metal ion much less effectively in an axial-equatorial mode. The results were compared with those on the carboxylate analogues iminodiacetic acid and nitrilotriacetic acid.