Solution coordination chemistry of actinides: Thermodynamics, structure and reaction mechanisms

An in-situ X-ray absorption spectroelectrochemical study of the electroreduction of uranium ions in HCl, HNO3, and Na2CO3 solutions

“…Detailed information about the local structure around the atoms of a specific element can be obtained from X-ray absorption fine structure (XAFS). Numerous XAFS studies of the coordination structure of uranium complexes have been conducted and reviewed [2][3][4][5][6][7]. The technique enables the identification of the valence states of uranium during the redox reactions from the X-ray absorption near-edge structure (XANES [8][9][10][11][12][13].…”

DFT modeling of the relative affinity of nitrogen ligands for trivalent f elements: an energetic point of view

“…To date, theoretical studies dedicated to trivalent rare earth complexes have thus been mainly applied to structural data, with very satisfying agreements, but other computational analyses, and notably energetic analyses, have seldom been validated. [39][40][41] Yet, even though structural parameters can account for covalency effects, they cannot differentiate systems on the basis of their relative stability. Only energetic data-complexation constants, free energies-can provide such information and are thus useful to explain the observed selectivity in actinide/ lanthanide extractions.…”

Single‐Electron Uranyl Reduction by a Rare‐Earth Cation

“…[7,8] Usually the [UO 2 ] + cation decomposes by disproportionation, which is also a poorly understood process, but is important in the precipitation of uranium salts out of aqueous environments. [9,10] The disproportionation is suggested, by analogy with the transuranic metal oxo Lewis base behavior, to involve the formation of cation-cation interactions (CCIs) [11,12] in which the oxo groups ligate to adjacent actinyl centers forming diamond (A) or T-shaped (B) dimers or clusters which can then allow the transfer of protons and electrons between metals, such as in C. [13] We reported that the use of rigid, Pacman-shaped macrocycles can allow the isolation of heterobimetallic uranyltransition metal complexes that form an oxo interaction with the transition metal in the solid state and solution, [14] and how the inclusion of more than one metal cation alongside the uranyl cation led to isolable, stable pentavalent uranyl complexes with a covalently functionalized oxo group. [15] More recently, pentavalent uranyl complexes with Group 1 cation oxo-coordination, [16] and a doubly silylated complex [17] have been isolated.…”