Thermodynamics of mixed-ligand complex formation of mercury (II) ethylenediaminetetraacetate with amino acids in solution

The mixed-ligand complex formation in the systems Hg2+ − Edta4− − L−(L = Arg, Orn, Ser) has been studied by means of calorimetry, pH-potentiometry and NMR spectroscopy in aqueous solution at 298.15 K and the ionic strength of I = 0.5 (KNO3). The thermodynamic parameters of formation of the HgEdtaL, HgEdtaHL and (HgEdta)2L complexes have been determined. The most probable coordination mode for the complexone and the amino acid in the mixed-ligand complexes was discussed.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Stable mixed ligand complexes of HgEdta with amino acids at physiological pH value. ► The thermodynamic and NMR data evident the ambidentate coordination mode of arginine. ► Participation of the guanidinic group of Arg in coordination process. ► Binuclear complexes (HgEdta)2L with the bridging function of amino acid.