Spectrophotometric study of complex formation in copper(II) mono-, di-, and tri-ethanolamine systems

Abstract

The complex formation between Cu^II and mono-, di-, or tri-ethanolamine, NH_{3 –n}R_n(R = CH₂CH₂OH, n= 1–3), has been studied using visible spectroscopy at ionic strength 1.0 mol dm^–3 and 25 °C. Ehanolamines are found to act as multidentate ligands through amino, hydroxyl, and deprotonated hydroxyl groups. The formation constants and the individual spectra of all the complex species detected between pH 2 and 12 have been obtained by least-squares fit of visible spectrophotometnc titration data. As an essential aid to understanding the copper(II)–triethanolamine system, the power of u.v.–visible spectrophotometry to distinguish between monomer and dimer species was especially studied. Two new soluble complex species were identified in this system.