New Insights into Formation of Trivalent Actinides Complexes with DTPA

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• 作者：S茅bastien Leguay ; Thomas Vercouter ; Sylvain Topin ; Jean Aupiais ; Dominique Guillaumont ; Manuel Miguirditchian ; Philippe Moisy ; Claire Le Naour
• 刊名：Inorganic Chemistry
• 出版年：2012
• 出版时间：December 3, 2012
• 年：2012
• 卷：51
• 期：23
• 页码：12638-12649
• 全文大小：477K
• 年卷期：v.51,no.23(December 3, 2012)
• ISSN：1520-510X

文摘

Complexation of trivalent actinides with DTPA (diethylenetriamine pentaacetic acid) was studied as a function of pcH and temperature in (Na,H)Cl medium of 0.1 M ionic strength. Formation constants of both complexes AnHDTPA^{鈥?/sup> and AnDTPA2鈥?/sup> (where An stands for Am, Cm, and Cf) were determined by TRLFS, CE-ICP-MS, spectrophotometry, and solvent extraction. The values of formation constants obtained from the different techniques are coherent and consistent with reinterpreted literature data, showing a higher stability of Cf complexes than Am and Cm complexes. The effect of temperature indicates that formation constants of protonated and nonprotonated complexes are exothermic with a high positive entropic contribution. DFT calculations were also performed on the An/DTPA system. Geometry optimizations were conducted on AnDTPA2鈥?/sup> and AnHDTPA鈥?/sup> considering all possible protonation sites. For both complexes, one and two water molecules in the first coordination sphere of curium were also considered. DFT calculations indicate that the lowest energy structures correspond to protonation on oxygen that is not involved in An鈥揇TPA bonds and that the structures with two water molecules are not stable.}