Synthesis and structural studies of a new potassium uranyl selenate K(H5O2)[(UO2)2(SeO4)3(H2O)] with strongly deformed layers

Single crystals of a new uranyl selenate, K(H5O2)[(UO2)2(SeO4)3(H2O)] (I), were prepared by isothermal evaporation at room temperature. The crystal structure of I was solved by the direct method (space group P21/c; a = 11.456(2), b = 10.231(1), c = 14.809(2) Å; β = 101.901(4)°, V = 1698.4(4) Å3; Z = 4) and refined to R 1 = 0.0547 (wR 2 = 0.0825) for 3375 reflections with |F o| ≥ 4σ F . The structure of I is based on layers of the composition [(UO2)2(SeO4)3(H2O)]2−. The charge of the inorganic layer is compensated by potassium and oxonium ions located in the interlayer space. Each potassium ion is coordinated by seven oxygen atoms belonging to uranyl selenate layers, including uranyl oxygen atoms, which leads to bending of uranyl selenate structural elements.