“…Ligand classes considered were: (1) O-donor ligands, such as di- (succinate), tetra- (1,2,3,4-butanetetracarboxylate), and hexa- (1,2,3,4,5,6-benzenehexacarboxylate) carboxylates, and polyelectrolytes, such as polymethacrylate and polyacrylates, at two different molecular weights; (2) N-donor ligands, such as amines containing a different number of aminic groups (from ethylenediamine to tetraethylenepentamine), and polyelectrolytes, such as poly(allylamine) and poly(ethylenimine); and (3) amino acids such as glycine containing one carboxylic and one amino group, histidine containing an additional amino group, and aspartic acid containing an additional carboxylic group. Hg 2+ −carboxylate, −amine, and −amino acid systems reported in the literature are collected in Table . − In this article, equilibria were studied potentiometrically in NaNO 3 at I = 0.1 mol·L −1 and t = 25 °C. Under the same conditions, for Hg 2+ −1,2,3,4-butanetetracarboxylate, −1,2,3,4,5,6-benzenehexacarboxylate, −diethylenetriamine, −poly(ethylenimine), and −glycine systems, the enthalpy changes by calorimetric measurements were also determined.…”