(CuBr)3P4Se4:: A low symmetric variant of the (CuI)3P4Se4 structure type

Bright orange (CuBr)(3)P4Se4 is obtained from the reaction of CuBr, P, and Se in stoichiometric amounts (CuBr : P : Se = 3 4 : 4). The composition and the crystal structure of the compound were determined from single crystal X-ray diffraction data. Lattice constants are a = 33.627(2) Angstrom, b = 6.402(1) Angstrom, c = 19.059(1) Angstrom, beta = 90.19(3)degrees, V = 4103.2(3) Angstrom(3), and Z = 12. The compound crystallizes in a structure that is related to (CUI)3P4Se4. Cages of beta-P4Se4 are stacked along the b-axis and are separated by columns of copper(I) bromide. However, the coordination of the beta-P4Se4 cage molecules to the copper atoms in the CuBr columns in (CuBr)(3)P4Se4 is quite different from (CuI)(3)P4Se4. The monoclinic compound (space group: P2(1), no. 4) has an almost orthorhombic metric in combination with a threefold superstructure in [100]. Structural aspects of (CuBr)(3)P4Se4 are discussed with respect to the heavier homologue (CuI)(3)P4Se4.