Thermodynamics of Mixed-Ligand Complex Formation of Mercury(II) Ethylenediaminetetraacetate with Ethylenediamine and Hexamethylenediamine in an Aqueous Solution

The thermodynamic parameters (logK, Δ _r G ⁰, Δ _r H, Δ _r S) of formation of the HgEdtaL^2?, HgEdtaHL^? and (HgEdta)₂L^4? complexes (L = NH₂(CH₂)₂NH₂, NH₂(CH₂)₆NH₂) have been determined by the calorimetric and pH-metric methods at 298.15 K and the ionic strength I = 0.5 (NaClO₄). The most probable coordination mode for the complexone and an ancillary ligand in the composition of the mixed complexes was discussed.