(CuBr) 3 P 4 Se 4 : A Low Symmetric Variant of the (CuI) 3 P 4 Se 4 Structure Type

Bright orange (CuBr) 3 P 4 Se 4 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) Å, b = 6.402(1) Å, c = 19.059(1) Å, β = 90.19(3) °, V = 4103.2(3) Å 3 , and Z = 12. The compound crystallizes in a structure that is related to (CuI) 3 P 4 Se 4 . Cages of β ‐P 4 Se 4 are stacked along the b ‐axis and are separated by columns of copper(I) bromide. However, the coordination of the β ‐P 4 Se 4 cage molecules to the copper atoms in the CuBr columns in (CuBr) 3 P 4 Se 4 is quite different from (CuI) 3 P 4 Se 4 . The monoclinic compound (space group: P 2 1 , no. 4) has an almost orthorhombic metric in combination with a threefold superstructure in [100]. Structural aspects of (CuBr) 3 P 4 Se 4 are discussed with respect to the heavier homologue (CuI) 3 P 4 Se 4 .