Thermodynamics of Ternary Complex Formation of Copper(II) and Nickel Iminodiacetates with Histidine in Solution

Calorimetric, potentiometric and spectrophotometric studies on the mixed–ligand complexes of copper(II) with nickel iminodiacetates (Ida) and histidine (His) have been carried out in aqueous solution at 298.15 K and ionic strength I = 0.5 mol·dm^?3 (KNO₃). The thermodynamic parameters of formation of various mixed complexes have been determined. The probable coordination modes of the complexone and histidine residues in the mixed ligand complexes are discussed.