The crystal structure of a previously unknown compound KNa3[(UO2)5O6(SO4)] [space group Pbca, a = 13.2855(15), b = 13.7258(18), c = 19.712(2) Å, V = 3594.6(7) Å3] was solved by direct methods and refined to R1 = 0.055 for 3022 reflections with |Fhkl| ≥ 4σ |Fhkl|. In the structure there are five sym-metrically nonequivalent uranyl cations. They are linked by cationcation (CC) interactions to form a pentamer whose central cation is U(2)O22+ forming two three-centered CC bonds. All the uranyl ions are coordinated in the equatorial plane by five O atoms, which leads to the formation of pentagonal bipyramids sharing common edges to form layers parallel to the (100) plane. The sulfate tetrahedron links the uranyl layers into a 3D framework. The K+ and Na+ cations are arranged in framework voids. A brief review of CC interactions in U(VI) compounds is presented.
PACS numbers61.10.Nz 61.66.Fn
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