Potentiometric study of mixed ligand complex formation in the copper(II)-salicylate-mono, DI-, and triethanolamine systems

Mixed ligand complexation between Cu(II) ion, salicylate ion, and mono- di- or triethanolamine is studied potentiometrically at 25° and 1.0 mol dm-3 ionic media. Protonation of the three ethanolamines and their binary complexation with Cu(II) are also studied under the same conditions. Values for the stability constants of all detected species are given. In the copper(II) binary complexes, ethanolamines act as a multidentate ligand through the amino and hydroxyl groups. Mixed ligand complex formation results very favoured in the case of di- and triethanolamine Some reasons are given to explain the observed stabilization of the detected mixed species.