AnIVFeII(CN)6·xH2O (An = Th, U, Np) molecular compounds have been prepared by precipitation from acidic media. These microcrystalline compounds have been characterized by infrared spectroscopy, X-ray diffraction, and X-ray absorption spectroscopy. They have been found to be isostructural with the LnIIIKFeII(CN)6·4H2O compounds. The molecular structures of these compounds are presented and their chemical formulas are given: in all compounds, the Fe(CN)6 octahedra is conserved and the An ion is linked to the N atoms of the CN ligands. The formal oxidation states are also discussed.Key words: hexacyanoferrate, actinide, EXAFS, XANES, X-ray absorption spectroscopy.
The coordination and redox chemistry of aqueous CeIV/III macrocyclic compounds were studied by using the ligands DOTA and DOTP (1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetrayl)tetraacetic acid and 1,4,7,10‐tetraazacyclododecane‐1,4,7,10‐tetra(methylene phosphonic acid), respectively). The hydrolysis tendency of the tetravalent cation in the presence of DOTA is shown to result in the formation of a highly ordered, fluorite‐like [CeIV6(O)4(OH)4(H2O)8(DOTAH)4] oxo‐hydroxo structure both in solution and in the solid state. The lifetime of the analogous species formed in the presence of DOTP was found to be much shorter. Spectroscopic measurements of the latter suggest its similarity to the former. Its gradual decomposition in solution leads to the accumulation of the in‐cage complexes [CeIVDOTP] and [CeIIIDOTP(H2O)], which were crystallographically characterized in this study. The redox energetics and spectroscopic characteristics for the transition between these two in‐cage complexes in aqueous solutions were studied as well. Together with the crystallographic structures of the above‐mentioned species, the in‐cage [CeIVDOTA(H2O)] complex structure is presented herein for the first time. An elaborative analysis of the X‐ray crystallographic structural data obtained for the in‐cage complexes studied herein and similar structures published previously suggests that hard‐bonding cyclen‐derived ligands are, counter‐intuitively, better suited for encapsulating, and perhaps kinetically stabilize softer cations than harder ones with DOTP, marked as a possible adequate chelator for the study of the aqueous properties of LnII and AcIII cations.
2006
X-ray spectra D 6510First Structural Characterization of a Protactinium(V) Single Oxo Bond in Aqueous Media. -Structural studies of Pa V are performed in H2SO4 and HF media using X-ray absorption spectroscopy. The results show unambiguously the absence of the trans-dioxo bond that characterizes the other early actinide elements such as U and Np. In conc. H2SO4, Pa V is proved to exhibit a single oxo bond as postulated in the literature for species in more dilute media. In a 0.5 M HF medium, XANES and EXAFS spectra indicate the absence of any oxo bond, i.e. Pa V exists in the form of a pure fluoro complex. -(LE NAOUR, C.; TRUBERT, D.; DI GIANDOMENICO, M. V.; FILLAUX, C.; DEN AUWER*, C.; MOISY, P.; HENNIG, C.; Inorg. Chem. 44 (2005) 25, 9542-9546; CEA Marcoule, DEN/DRCP/Serv. Chim. Proc. Sep., F-30207 Bagnols sur Ceze, Fr.; Eng.) -Schramke 09-014
Thermodynamic functions E 3000Uranyl (VI) Nitrate Salts: Modeling Thermodynamic Properties Using the Binding Mean Spherical Approximation Theory and Determination of "Fictive" Binary Data. -(RUAS, A.; BERNARD, O.; CANIFFI, B.; SIMONIN, J.-P.; TURQ, P.; BLUM, L.; MOISY*, P.; J. Phys. Chem. B 110 (2006) 7, 3435-3443; CEA Marcoule, DEN/DRCP/Serv. Chim. Proc. Sep., F-30207 Bagnols sur Ceze, Fr.; Eng.) -Schramke 16-021
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