Synthesis and Characterization of Copper Hexathiometadiphosphate Cu 2 P 2 S 6

Copper hexathiometadiphosphate, Cu 2 P 2 S 6 , was synthesized and characterized. Brick‐red copper hexathiometadiphosphate Cu 2 P 2 S 6 crystallizes in the tetragonal space group P 4 2 / mnm (no. 136) with a = b = 5.2565(7), c = 15.066(3) Å and V = 416.3(1) Å 3 in a novel structure type. This is the first hexathiometadiphosphate, whose crystal structure is based on a slightly distorted cubic closest packing of sulfur atoms. 1/3 of the tetrahedral voids are occupied by Cu and P in an ordered fashion, thus resulting in a layered structure. The structural motif of layers composed of corner‐sharing CuS 4 tetrahedra (comparable to red HgI 2 ) that are separated by [P 2 S 6 ] 2– anions orientated perpendicular to these layers, is rarely found in solid state chemistry. The compound is diamagnetic and shows negligible electronic conductivity. Electronic structure calculations and UV/Vis measurements point to a bandgap in the visible range and explain the red color of the compound. Additionally, the oxidation state +1 for Cu was confirmed by the electronic structure calculations. The thermal properties of Cu 2 P 2 S 6 were investigated by DTA.