Mixed ligand complexes. Log β, ΔH°, and ΔS° values for the Cu2+–glycine, –alanine, –α-aminoisobutyric acid, and sarcosine systems

Abstract

Values of log β, ΔH°, and ΔS° are reported for mixed-ligand complex formation of Cu²⁺ with amino-acids in dilute aqueous solution. The reaction Cu²⁺+ A^–+ B^–= CuAB is characterized for the systems involving glycine, alanine, sarcosine, and aminoisobutyric acid as ligands. The thermochemical results are discussed in terms of a statistical model and it is shown that the enhancement factor term applied to mixed-ligand formation constants does not necessarily arise from the entropy term.