The crystal structure of triuranyl diphosphate tetrahydrate

摘要

The hydrated neutral uranyl phosphate, (UO2)(3)(PO4)(2)(H2O)(4), was synthesized by hydrothermal methods. Intensity data were collected using MoKalpha radiation and a CCD-based area detector. The crystal structure was solved by direct methods and refined by full-matrix least-squares techniques to agreement indices wR(2) = 0. 116 for all data, and R1 = 0.040, calculated for the 2764 unique observed reflections (F greater than or equal to 4sigma(F)). The compound is orthorhombic, space group Pnma, Z = 4, a = 7.063(1) Angstrom, b = 17.022(3) Angstrom, c = 13.172(3) Angstrom, V= 1583.5(5) Angstrom(3). The structure consists of sheets of phosphate tetrahedra and uranyl pentagonal bipyramids, with composition [(UO2)(PO4)](-) and the uranophane sheet anion topology. The sheets are connected by a uranyl pentagonal bipyramid in the interlayer that shares corners with a phosphate tetrahedron on each of two adjacent sheets, resulting in an open framework with isolated H2O groups in the larger cavities of the structure. (C) 2002 Elsevier Science. [References: 30]