CUCLCU2TES3 - SYNTHESIS, STRUCTURE DETERMINATION, AND RAMAN-SPECTROSCOPIC CHARACTERIZATION OF A NEW ZINCBLENDE DERIVATIVE

Pure black CuClCu2TeS3 was prepared by reaction of stoichiometric amou nts of CuCl, Cu, Te, and S in evacuated silica ampules. The crystal st ructure was determined from single crystals at room temperature. The c ompound crystallizes in the rhombohedral system, space group R3m with a = 7.361(1) Angstrom and c = 10.401(1) Angstrom (hexagonal setting), and Z = 3. Structural considerations and group-subgroup relationships show that CuClCu2TeS3 can be regarded as a new ordered zincblende deri vative. In this material copper and sulfur are four-coordinate. By con trast tellurium has a trigonal pyramidal coordination and chlorine is located in a trigonal planar surrounding. Raman spectra are dominated by stretching modes of thiometalate ions [TeS3](2-) at nu(asym) = 359 cm(-1) and nu(sym) = 336 cm(-1), respectively. DTA measurements reveal a peritectic decomposition of CuClCu2TeS3 at 448 degrees C.