Homo- and heteroleptic mercury(II) complexes with monoamino complexones in aqueous solution

Reactions of mercury(II) with iminodiacetic (H(2)Ida), 2-hydroxyethyliminodiacetic (H(2)Heida), and nitrilotriacetic acids (H(3)Nta) were studied by spectrophotometry and pH potentiometry. The resulting complexes included [HgIda], [Hg(OH)Ida](-), [HgIda(2)](2-), [HgHeida], [Hg(OH)Heida](-), [Hg(Heida)(2)](2-), [HgNta](-), [HgNta(2)](4-), [Hg(Ida)Heida](2-)[Hg(Ida)Nta](3-), and [Hg(Heida)Nta](3-). The logarithms of their stability constants calculated for I = 0.1 (NaClO4) and T = 20 +/- 2 degrees C were 11.14 +/- 0.07, 20.33 +/- 0.08, 19.40 +/- 0.10, 11.42 +/- 0.04, 19.68 +/- 0.11, 18.48 +/- 0.09, 13.42 +/- 0.05, 20.80 +/- 0.08, 19.05 +/- 0.06, 20.64 +/- 0.11, and 20.53 +/- 0.16, respectively. The experimental data were analyzed in terms of the mathematical models that predict the existence of a wide spectrum of complex species in solution and allow one to consider only those species that are sufficient for accurate reproduction of the observed pattern.