Crystal Chemistry of Selenates with Mineral-Like Structures: V. Crystal Structures of(H_3O)_2[(UO_2)(SeO4)_2(H_2O)](H_2O)_2 and(H_3O)_2[(UO_2)(SeO_4)_2(H_2O)](H_2O), New Compounds with Rhomboclase and Goldichite Topology

摘要

The crystal structures of two new compounds(H3O)2[(UO2)(SeO4)2(H2O)](H2O)2(1,orthorhom-bic,Prima,a = 14.0328(18),b = 11.6412(13),c = 8.2146(13)A,V = 134.9(3)A~3)and(H3O)2[(UO2)(SeO4)2(H2O)](H2O)(2,monoclinic,P2xlc,a = 7.8670(12),b = 7.5357(7),c = 21.386(3)A,beta =101.484(12)°,V = 1242.5(3)A3)have been solved by direct methods and refined to R1 = 0.076 and 0.080,respectively.The structures of both compounds contain sheet complexes [(UO2)(SeO4)2]~(2-)formed by corner-shared [(UO2)O4(H2O)] bipyramids and SeO4 tetrahedrons.The sheets are parallel to the(100)plane in structure 1 and to(-102)in structure 2.The [(UO2)(SeO4)2(H2O)]~(2-)layers are linked by hydrogen bonds via inter-layer groups H2O and H3O~+.The sheet topologies in structures 1 and 2 are different and correspond to the topologies of octahedral and tetrahedral complexes in rhomboclase(H2O2)~+[Fe(SO4)2(H2O)2] and goldichite K[Fe(SO4)2(H2O)2](H2O)2,respectively.