BINARY AND TERNARY COMPLEXES OF CADMIUM(II) INVOLVING N-(2-ACETAMIDO)IMINODIACETIC ACID AND AMINO-ACIDS

The present work examines the acid-base equilibria of N(2-acetamido)im inodiacetic acid (ADA) and the binary and ternary complexes of cadmium (II) with ADA and amino acids. Cd(II) is found to form a 1:1 complex w ith ADA. The ternary complexes are formed in a stepwise mechanism, whe reby the ADA binds to Cd(II), then follows ligation of the amino acid in a glycine-like mode. The amino acids histidine, ornithine, lysine, penicillamine, cysteine and glutathione form protonated and deprotonat ed ternary complexes. The stability constants of the ternary complexes have been quantified in relation to the corresponding binary complexe s. The concentration distribution of the various complex species has b een evaluated.