The sharing of an edge between a uranyl pentagonal bipyramid and sulfate tetrahedron in the structure of KNa5[(UO2)(SO4)4](H2O)

The new uranyl sulfate compound KNa5[(UO2)(SO4)(4)](H2O) has been synthesized and its structure has been determined. It is monoclinic, space group C2/c, a 16.917(1), b 5.5999(5), c 35.340(3) Angstrom, beta 90.437(2)degrees, V 3347.7(5) Angstrom(3), Z = 8. The structure has been solved and refined on the basis of F-2 for all unique data collected with monochromatic MoKalpha X-radiation and a CCD-based detector to an agreement factor R I of 3.6%, calculated using 4981 unique observed reflections (F-o greater than or equal to 4sigma(F)). The structure contains an unusual uranyl sulfate cluster with composition [(UO2)(SO4)(4)](6-). The cluster is composed of a uranyl pentagonal bipyramid and four sulfate tetrahedra. Three sulfate tetrahedra are linked to the uranyl pentagonal bipyramid by the sharing of vertices, and the other shares an equatorial edge of the uranyl pentagonal bipyramid. The uranyl sulfate clusters are linked through bonds to K and Na cations, and by H bonding. The uranyl sulfate cluster, which was recently also found in two Na uranyl sulfates, is unusual in the sharing of an edge between a uranyl polyhedron and a M6+O4 tetrahedron.