Crystal Chemistry of Selenates with Mineral-Like Structures:VII. The Structure of (H3O)[(UO2)(SeO4)(SeO2OH)] and Some Structural Features of Selenite-Selenates

摘要

The crystal structure of a new compound, (H3O)[(UO2)(SeO4)(SeO2OH)] (monoclinic, P2_1, a = 8.6682(19), b = 10.6545(16), c = 9.846(2) A, β = 97.881(17)°, V= 900.7(3) A~3), was solved by direct methods and refined to R1 = 0.050. The structure contains two symmetrically different Se atoms. The Sel site is coordinated by three O atoms as is characteristic of Se~(4+) cations. The Se2 site is coordinated by four O atoms and forms selenate anion SeO4~(2-). The structure is based on selenite-selenate sheets [(UO2)(SeO4)(SeO2OH)]~-linked by the interlayer H3O~- ions. The sheets are parallel to (101). The structure is compared to that of schmiederite, Pb2Cu2(SeO3)(SeO4)(OH)4.