Formation of mono- and binuclear neodymium(III)-gluconate complexes in aqueous solutions in the pH range of 2-8

Bence Kutus, Norbert Varga, Gábor Peintler, Alexandru Lupan, Amr A.A. Attia, István Pálinkó, Pál Sipos

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4 Citations (Scopus)

Abstract

The complex formation between Nd(iii) and d-gluconate (Gluc-) is of relevance in modelling the chemical equilibria of radioactive waste repositories. In the present work, the formation of NdpGlucqH-r complexes at 25 °C and pH = 2-8 was studied via spectrophotometry, potentiometry, freezing point depression, conductometry and NMR spectroscopy. In addition to the four mononuclear complexes (pq-r = 110, 120, 130 and 11-2), the formation of two binuclear, so far unknown complexes (pq-r = 23-2 and 24-2) was revealed. Between pH = 5.5 and 7, with the increasing metal ion and ligand concentrations, the Nd2Gluc3H-2+ species becomes progressively predominant. Under the conditions characteristic of waste repositories, however, the formation of these complexes can be neglected. Regarding the binding sites of Gluc-, C2-OH and C3-OH groups, in addition to the carboxylate ion, were identified from 1H and 13C spectroscopic measurements. Above pH = 6, the metal-ligand interactions became stronger implying the formation of deprotonated complexes involving the C2-OH group, while the displacement of the second proton at the C3-OH is also possible. The metal ion induced deprotonation of the ligand was confirmed by DFT calculations.

Original languageEnglish
Pages (from-to)6049-6058
Number of pages10
JournalDalton Transactions
Volume46
Issue number18
DOIs
Publication statusPublished - Jan 1 2017

ASJC Scopus subject areas

  • Inorganic Chemistry

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