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Title: The Structure of Uranyl Sulfate in Aqueous Solution - Monodentate Versus Bidentate Coordination

Abstract

The structure of U(VI) aquo sulfato complexes has been investigated by LIII-edge EXAFS spectroscopy. A monodentate coordination with a U-Smon distance of 3.57{+-}0.02 A prevails in equimolar [SO{sub 4}{sup 2-}]{sub total}/U(VI) solutions. With increasing [SO{sub 4}{sup 2-}]{sub total}/U(VI) ratio, bidentate coordination with a U-Sbid distance of 3.11{+-}0.02 A becomes dominant.

Authors:
; ; ; ; ;  [1]
  1. Forschungszentrum Rossendorf, Institute of Radiochemistry, P.O. Box 510119, 01314 Dresden (Germany)
Publication Date:
OSTI Identifier:
21054610
Resource Type:
Journal Article
Resource Relation:
Journal Name: AIP Conference Proceedings; Journal Volume: 882; Journal Issue: 1; Conference: XAFS13: 13. international conference on X-ray absorption fine structure, Stanford, CA (United States), 9-14 Jul 2006; Other Information: DOI: 10.1063/1.2644495; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; ABSORPTION SPECTROSCOPY; AQUEOUS SOLUTIONS; FINE STRUCTURE; LIQUIDS; SULFUR COMPLEXES; URANIUM IONS; URANYL SULFATES; X-RAY SPECTROSCOPY

Citation Formats

Hennig, C., Schmeide, K., Brendler, V., Moll, H., Tsushima, S., and Scheinost, A. C. The Structure of Uranyl Sulfate in Aqueous Solution - Monodentate Versus Bidentate Coordination. United States: N. p., 2007. Web. doi:10.1063/1.2644495.
Hennig, C., Schmeide, K., Brendler, V., Moll, H., Tsushima, S., & Scheinost, A. C. The Structure of Uranyl Sulfate in Aqueous Solution - Monodentate Versus Bidentate Coordination. United States. doi:10.1063/1.2644495.
Hennig, C., Schmeide, K., Brendler, V., Moll, H., Tsushima, S., and Scheinost, A. C. Fri . "The Structure of Uranyl Sulfate in Aqueous Solution - Monodentate Versus Bidentate Coordination". United States. doi:10.1063/1.2644495.
@article{osti_21054610,
title = {The Structure of Uranyl Sulfate in Aqueous Solution - Monodentate Versus Bidentate Coordination},
author = {Hennig, C. and Schmeide, K. and Brendler, V. and Moll, H. and Tsushima, S. and Scheinost, A. C.},
abstractNote = {The structure of U(VI) aquo sulfato complexes has been investigated by LIII-edge EXAFS spectroscopy. A monodentate coordination with a U-Smon distance of 3.57{+-}0.02 A prevails in equimolar [SO{sub 4}{sup 2-}]{sub total}/U(VI) solutions. With increasing [SO{sub 4}{sup 2-}]{sub total}/U(VI) ratio, bidentate coordination with a U-Sbid distance of 3.11{+-}0.02 A becomes dominant.},
doi = {10.1063/1.2644495},
journal = {AIP Conference Proceedings},
number = 1,
volume = 882,
place = {United States},
year = {Fri Feb 02 00:00:00 EST 2007},
month = {Fri Feb 02 00:00:00 EST 2007}
}
  • Single crystals of Cs{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} and Rb{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2} were prepared by solid state reactions. The structures are based upon the [(UO{sub 2})(CrO{sub 4}){sub 2}]{sup 2-} chains. Within the chains, UrO{sub 5} pentagonal bipyramids (Ur=uranyl) form Ur{sub 2}O{sub 8} dimers, which are linked via CrO{sub 4} tetrahedra into one-dimensional chains. The CrO{sub 4} tetrahedra coordinate uranyl ions in both mono- and bidentate fashion, which is unusual for uranyl chromates. The bidentate coordination has a strong influence upon geometrical parameters of both U and Cr coordination polyhedra. The conformation of the chains in 1 and 2more » is different due to the different size of the Cs{sup +} and Rb{sup +} cations. - Graphical abstract: Uranyl chromate chain with monodentate and bidentate coordination mode of uranyl cations by CrO{sub 4} tetrahedra in Cs{sub 2}(UO{sub 2})(CrO{sub 4}){sub 2}. Highlights: Black-Right-Pointing-Pointer Single crystals of novel uranyl chromates were prepared by solid state reactions. Black-Right-Pointing-Pointer The CrO{sub 4} tetrahedra coordinate uranyl ions in both mono- and bidentate fashion. Black-Right-Pointing-Pointer The bidentate coordination has a strong influence upon geometrical parameters.« less
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  • To evaluate the ability of X-ray absorption fine structure (XAFS) spectroscopy to elucidate the coordination environment of U{sup 6+} at the solid-water interface, we conducted an in-depth analysis of experimental XAFS data from U{sup 6+} solid and solution model compounds. Using the ab initio XAFS code FEFF6, we calculated phase-shift and amplitude functions for fitting experimental data. The code FEFF6 does a good job of reproducing experimental data and is particularly valuable for providing phase-shift and amplitude functions for neighboring atoms whose spectral contributions are difficult to isolate from experimental data because of overlap of Fourier transform features. In solid-phasemore » model compounds at ambient temperature, we were able to fit spectral contributions from axial O (1.8 {Angstrom}), equatorial O (2.2-2.5 {Angstrom}), N (2.9 {Angstrom}), C (2.9 {Angstrom}), Si (3.2 {Angstrom}), P (3.6 {Angstrom}), distant 0 (4.3 {Angstrom}), and U (4.0, 4.3, 4.9, and 5.2 {Angstrom}) atoms. Contributions from N, C, Si, P, distant O, and distant U (4.9 and 5.2 {Angstrom}) are weak and therefore might go undetected in a sample of unknown composition. Lowering the temperature to 10 K extends detection of U neighbors to 7.0 {Angstrom}. The ability to detect these atoms suggests that XAFS might be capable of discerning inner-sphere U sorption at solid aluminosilicate-water interfaces. XAFS should definitely detect multinuclear U complexes and precipitates. Multiple-scattering paths are minor contributors to uranyl XAFS beyond k = 3 {Angstrom}{sup -1}. Allowing shell-dependent disorder parameters ({sigma}{sup 2}) to vary, we observed narrow ranges of {sigma}{sup 2} values for similar shells of neighboring atoms. Knowledge of these ranges is necessary to constrain the fit of XAFS spectra for unknowns. Finally, we found that structures reported in the literature for uranyl diacetate and rutherfordine are not completely correct. 50 refs., 6 figs., 2 tabs.« less
  • Bis(diisopropyl(1,2-bis(diethylcarbamoyl)ethyl)phosphonate)erbium(III) nitrate monohydrate, Er(NO/sub 3/)/sub 3/(i-C/sub 3/H/sub 7/O)/sub 2/P(O)CH-(C(O)N(C/sub 2/H/sub 5/)/sub 2/)(CH/sub 2/C(O)N(C/sub 2/H/sub 5/)/sub 2/))/sub 2/.H/sub 2/O, has been prepared from the trifunctional phosphate ligand and Er(NO/sub 3/)/sub 3/.6H/sub 2/O in ethanol. The complex has been characterized by infrared and NMR spectroscopy and single-crystal X-ray diffraction analysis. The complex was found to crystallize in the monoclinic space group P2/sub 1//n with a = 13.438 (2) A, b = 22.022 (4) A, c = 19.596 (5) A, ..beta.. = 106.21 (2)/sup 0/, Z = 4, V = 5568 (2) A/sup 3/, and rho/sub calcd/ = 1.38 g cm/sup -3/. Themore » structure was solved by heavy-atom techniques. The structure contains an Er(III) ion bonded to the oxygen atom of a water molecule, oxygen atoms of three bidentate nitrate ions, and the phosphoryl oxygen atoms of two of the potentially tripodal ligand (i-C/sub 3/H/sub 7/O)/sub 2/P(O)CH(C(O)N(C/sub 2/H/sub 5/)/sub 2/)(CH/sub 2/C(O)N(C/sub 2/H/sub 5/)/sub 2/). The overall erbium ion coordination number is 9. Two of the four carbonyl oxygen atoms are hydrogen bonded with the coordinated water molecule, while the remaining two carbonyl oxygen atoms, remain uncoordinated. 12 references, 1 figure, 2 tables.« less