Ternary Complexes of Cadmium(II) with Phenylalanine and Phenylalkylmalonates in Dioxane–Water Mixtures

Abstract

The formation and stability of ternary complexes of cadmium(II) with phenylalanine and malonate, phenylmalonate benzylmalonate, 2-phenylethylmalonate, and 3-phenylpropylmalonate, have been studied by the potentiometric pH titration technique in 40% (v/v) dioxane–water at 25°C and 0.10—ionic strength (NaNO3). All systems give stable ternary complexes, and the Δ log K and δK values demonstrated that the complexes possess enhanced stability. The possible reasons that lead to these results are discussed in terms of π–electron back donation from metal ions to ligands and intramolecular ligand–ligand aromatic ring-stacking interactions present in the complexes. The relative contribution of each interactions to the enhanced stability have also been evaluated.