Advancing understanding of actinide(iii) (Ac, Am, Cm) aqueous complexation chemistry†

Autor: Laura M. Lilley, Jennifer N. Wacker, Karah E. Knope, Veronika Mocko, Maryline G. Ferrier, Zachary R. Jones, Frankie D. White, Stosh A. Kozimor, David H. Woen, Maksim Y. Livshits, Benjamin W. Stein, Brian L. Scott, Elodie Dalodière
Jazyk: angličtina
Rok vydání: 2021
Předmět:
Zdroj: Chemical Science
Chemical science, vol 12, iss 15
ISSN: 2041-6539
2041-6520
Popis: The positive impact of having access to well-defined starting materials for applied actinide technologies – and for technologies based on other elements – cannot be overstated. Of numerous relevant 5f-element starting materials, those in complexing aqueous media find widespread use. Consider acetic acid/acetate buffered solutions as an example. These solutions provide entry into diverse technologies, from small-scale production of actinide metal to preparing radiolabeled chelates for medical applications. However, like so many aqueous solutions that contain actinides and complexing agents, 5f-element speciation in acetic acid/acetate cocktails is poorly defined. Herein, we address this problem and characterize Ac3+ and Cm3+ speciation as a function of increasing acetic acid/acetate concentrations (0.1 to 15 M, pH = 5.5). Results obtained via X-ray absorption and optical spectroscopy show the aquo ion dominated in dilute acetic acid/acetate solutions (0.1 M). Increasing acetic acid/acetate concentrations to 15 M increased complexation and revealed divergent reactivity between early and late actinides. A neutral Ac(H2O)6(1)(O2CMe)3(1) compound was the major species in solution for the large Ac3+. In contrast, smaller Cm3+ preferred forming an anion. There were approximately four bound O2CMe1− ligands and one to two inner sphere H2O ligands. The conclusion that increasing acetic acid/acetate concentrations increased acetate complexation was corroborated by characterizing (NH4)2M(O2CMe)5 (M = Eu3+, Am3+ and Cm3+) using single crystal X-ray diffraction and optical spectroscopy (absorption, emission, excitation, and excited state lifetime measurements).
Actinide complexation from aqueous acetic acid/acetate buffered solutions is described. The number of water ligands was directly correlated with the acetate concentration and characterized by X-ray absorption and optical spectroscopy.
Databáze: OpenAIRE
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