Synthesis and crystal structure of Zn2[(UO2)3(SeO4)5](H2O)17

Single crystals of a new compound, Zn2[(UO2)3(SeO4)5](H2O)17, were prepared by evaporation from aqueous solution. The crystal structure (orthorhombic, Pbca, a = 18.4288(10), b = 19.9793(11), c = 20.6901(9) Å, V = 7618.0(7) Å3, Z = 8) has been solved by direct methods and refined to R1 = 0.047 on the basis of 7805 independent observed reflections. The structure is based upon [(UO2)3(SeO4)5]4− sheets consisting of corner-sharing UO7 pentagonal bipyramids and SeO4 groups. The sheets are oriented parallel to the (0 1 0) plane and are strongly modulated with the modulation vector oriented approximately parallel to the [1 0 1] direction. The Zn(H2O)6 octahedra and additional H2O groups are located in the interlayer providing three-dimensional linkage of the sheets via hydrogen bonds. Zn2[(UO2)3(SeO4)5](H2O)17 is isostructural to previously reported Mg2[(UO2)3(CrO4)5](H2O)17 and Cu2[(UO2)3((S,Cr)O4)5](H2O)17.