Mixed-ligand complex formation of mercury (II) ethylenediaminetetraacetate with cysteine and methionine in aqueous solution

摘要

The mixed-ligand complex formation in the systems Hg~(2+)-Edta ~(4-)-L (L = Cys~(2-), Met-) 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 (KNO_3). 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 is discussed.