Synthesis and structural study of new potassium uranyl selenates K2(H5O2)(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)4 and K3(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)5

Abstract

Single crystals of new uranyl selenates K2(H5O2)(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)4 (1) and K3(H3O)[(UO2)2(SeO4)4(H2O)2](H2O)5 (2) were prepared by isothermal evaporation at room temperature. The crystal structure of 1 was solved by the direct method [C2/c, a = 17.879(5), b = 8.152(5), c = 17.872(5) A, β = 96.943(5)°, V = 2585.7(19) A3, Z = 4] and refined to R 1 = 0.0449 (wR 2 = 0.0952) for 2600 reflections with |F o| ≥ 4σ F . The structure of 2 was solved by the direct method [P21/c, a = 17.8377(5), b = 8.1478(5), c = 23.696(1) A, β = 131.622(2)°, V = 2574.5(2) A3, Z = 4] and refined to R 1 = 0.0516 (wR 2 = 0.1233) for 4075 reflections with |F o| ≥ 4σ F . The structures of 1 and 2 are based on [(UO2)2(SeO4)4(H2O)2]4− layers. The charge of the inorganic layer is compensated by potassium and oxonium ions arranged in the interlayer space. Each K ion is surrounded by seven O atoms belonging to uranyl selenate layers and water molecules, so that it binds with each other the adjacent uranyl selenate structural elements.