title: Structural studies coupling X-ray diffraction and high-energy X-ray scattering in the UO2(2+)-HBr(aq) system.
abstract: The structural chemistry of uranium(VI) in concentrated aqueous hydrobromic acid solutions was investigated using both single crystal X-ray diffraction and synchrotron-based high-energy X-ray scattering (HEXS) to reveal the structure of the uranium(VI) complexes in solution prior to crystallization. The crystal structures of a series of uranyl tetrabromide salts are reported, including Cs(2)UO(2)Br(4), Rb(2)UO(2)Br(4)·2H(2)O, K(2)UO(2)Br(4)·2H(2)O, and (NH(4))(2)UO(2)Br(4)·2H(2)O, as well as a molecular dimer of uranium(VI), (UO(2))(2)(OH)(2)Br(2)(H(2)O)(4). Limited correspondence exists between the structures observed in the solid state and those in solution. Quantitative analysis of the HEXS data show an average U-Br coordination number of 1.9(2) in solution, in contrast to the U-Br coordination number of 4 in the solid salts.
authors.affiliation: Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, Illinois 60439, USA. rewilson@anl.gov
authors.forename: Richard E
authors.initials: RE
authors.lastname: Wilson
authors.forename: S
authors.initials: S
authors.lastname: Skanthakumar
authors.forename: C L
authors.initials: CL
authors.lastname: Cahill
authors.forename: L
authors.initials: L
authors.lastname: Soderholm