Cs₂UPd₃Se₆

Dicaesium uranium(IV) tripalladium(II) hexa-selenide, Cs ₂UPd₃Se₆, crystallizes in the space group Fmmm in the Ba₂NaCu₃O₆ structure type. The asymmetric unit comprises the following atoms with site symmetries as shown: U1 (mm2), Cs1 (222), Cs2 (m2m), Pd1 (.m.), Pd2 (2mm), Se1 (m..), and Se2 (1). This layered structure contains six edge-sharing square-planar [PdSe₄] units that form a hexa-gon. These, in turn, edge-share with [USe₆] trigonal-prismatic units, forming an extended layer parallel to (010). The layers are stacked along [010]. They are staggered, and are separated by the Cs atoms. The Cs atoms are either coordinated in a square anti-prism of Se atoms or are ten-coordinate, with one square face and the opposite face hexa-gonal.