title: New insights into formation of trivalent actinides complexes with DTPA.
abstract: 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(-) and AnDTPA(2-) (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 AnDTPA(2-) and  AnHDTPA(-) 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-DTPA bonds and that the structures with two water molecules are not stable.
authors.affiliation: CNRS-Université Paris-Sud, IPN 15 rue Georges Clémenceau, 91406 Orsay Cedex, France.
authors.forename: Sébastien
authors.initials: S
authors.lastname: Leguay
authors.forename: Thomas
authors.initials: T
authors.lastname: Vercouter
authors.forename: Sylvain
authors.initials: S
authors.lastname: Topin
authors.forename: Jean
authors.initials: J
authors.lastname: Aupiais
authors.forename: Dominique
authors.initials: D
authors.lastname: Guillaumont
authors.forename: Manuel
authors.initials: M
authors.lastname: Miguirditchian
authors.forename: Philippe
authors.initials: P
authors.lastname: Moisy
authors.forename: Claire
authors.initials: C
authors.lastname: Le Naour
mesh_terms: D008671:Actinoid Series Elements / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D004369:Pentetic Acid / Q000737:chemistry*; D011789:Quantum Theory
chemical_list: D008671:Actinoid Series Elements; D009942:Organometallic Compounds; D004369:Pentetic Acid