Single crystals of two isotypic uranyl compounds, [CH6N3]2[(UO2)2(SeO4)3] (1) è [CH6N3]2[(UO2)2(SO4)3] (2), have been prepared by isothermal evaporation from aqueous solutions. The crystal structure of compounds have been solved by direct methods (for (1) - monoclinic, P2, a = 9.9448(15) Å, b = 9.727(2) Å, c = 10.1508(15) Å, β = 90.213(12)°, V = 981.9(3) Å3; for (2) – orthorhombic, P21212; a = 9.907(3) Å, b = 9.597(3) Å, c = 9.762(3) Å, V = 928.2(5) Å3] and refined to R1 = 0.0696 (wR2 = 0.1611) for 2511 reflections with |Fo| ≥ 4σF and to R1 = 0.0249 (wR2 = 0.0578) for 2066 reflections with |Fo| ≥ 4σF, for (1) è (2), respectively. Both structures are based upon the [(UO2)2(ÒO4)3]2- (Ò=Se, S) layers formed by linkage of U and Se/S coordination polyhedra via common O atoms. The charge of the inorganic layer is compensated by guanidinium molecules arranged in the interlayer space.
Keywords: Uranyl compounds, uranyl selenates, uranyl sulfates, organo-inorganic compounds, symmetry, topology