Thermochemical data on adducts of copper chloride with the amino acids lysine and glycine

Abstract

Adducts of the general formula CuCl 2· nlys ( n=1, 2, 4; lys=lysine) and CuCl 2· ngly ( n=2, 4; gly=glycine) were prepared by reacting the ligands with CuCl 2 in solid state. The adducts were characterized by elemental analysis, infrared spectroscopy and thermogravimetry. In all cases, the cation is coordinated to the amino acids via amino and carbonyl groups. The standard molar enthalpy of reaction in the condensed phase: CuCl 2(c)+ xL(c)=CuCl 2· xL(c); Δ r H m°, was determined in aqueous solution by the ampoule-breaking method. From Δ r H m° and the standard enthalpies of formation of copper chloride and the ligands, the standard molar enthalpies of formation of the adducts were calculated. The decomposition, lattice and reaction enthalpies and the mean ligand–metal bond enthalpy were also determined through appropriate thermodynamic cycles.