Complexation of copper(II) with nitrilotriacetic acid in aqueous and water-acetonitrile solutions at variable concentrations of supporting electrolyte

Abstract

The pH-metric titration was used to determine dissociation constants of nitrilotriacetic acid (H3L) and to study its complexation with copper(II) in aqueous and water-acetonitrile solutions (t = 25 ± 0.05°C) at variable concentrations of a supporting electrolyte (μ = 0.5-3.0, NaClO4, NaNO3). The dissociation constants of H3L increase as the content of the supporting salt in an aqueous solution increases. The composition of the copper(II) nitrilotriacetate complexes in the presence of NaClO4 and NaNO3 is more complicated than in the presence of KNO3. A tendency of the carboxyl groups of H3L toward dissociation decreases and the stability of the similar copper(II) complexes increases in aqueous acetonitrile (Xs = 0.19 mole fractions) compared to those in an aqueous solution. © 1997 MAEe cyrillic signK Hayκa/Interperiodica Publishing.