Formation of mono- and binuclear neodymium(III)gluconate complexes in aqueous solutions in the pH range of 2-8
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 Nd(p)Gluc(q)H(-r) complexes at 25 degrees C and pH = 2-8 was studied via spectrophotometry, potentiometry, fre...
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| Dokumentumtípus: | Cikk |
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2017
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| Sorozat: | DALTON TRANSACTIONS
46 No. 18 |
| doi: | 10.1039/c7dt00909g |
| mtmt: | 30890697 |
| Online Access: | http://publicatio.bibl.u-szeged.hu/17554 |
| Tartalmi kivonat: | 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 Nd(p)Gluc(q)H(-r) complexes at 25 degrees 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 Nd(2)Gluc(3)H(-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 H-1 and C-13 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. |
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| Terjedelem/Fizikai jellemzők: | 6049-6058 |
| ISSN: | 1477-9226 |