Mixed-Ligand Nickel(II) Complexes with Histidine and Cysteine in Aqueous Solution: Thermodynamic Approach

Potentiometric and calorimetric study on mixed-ligand complexes of nickel(II) ion with histidine (His) and cysteine (Cys) has been carried out in aqueous solution at 298 K and the ionic strength of I = 0.5 mol·dm −3 (KNO 3 ). Possible coordination modes of amino acid residues in ternary complexes are discussed using comparative analysis of thermodynamic parameters of complex formation.