CUCLS0.94TE1.06 AND CUBRS0.92TE1.08, 2 NE W COPPER(I) CHALCOGEN HALIDES CONTAINING NEUTRAL (1)(INFINITY)[STE] SCREWS

CUClS0.94Te1.06 and CUBrS0.92Te1.08 are two new, isotypic compounds of general composition CuXYY' (X = halide, Y,Y' = chalcogen) with a mixe d chalcogen substructure. They crystallize in the monoclinic system, s pace group P2(1)/n (No. 14), a = 7.878(2), b = 4.727(1), c = 10.759(2) Angstrom, beta = 103.97(2)degrees, V = 388.8(2) Angstrom(3) (CuClS0.9 4Te1.06) and a = 8.043(3), b = 4.746(2), c = 11.240(4) Angstrom, beta = 103.46(3)degrees, V = 417.3(3) Angstrom(3) (CuBrS0.92Te1.08), both w ith Z = 4. The crystal structures are dominated by ordered (1)(infinit y)[STe+/-0]-screws. From crystal chemical point of view the sulfur and tellurium atoms are significantly different. The melting points are 3 41 degrees C (CuClS0.94Te1.06) and 336 degrees C (CuBrS0.92Te1.08). Th e compounds CuXYY' (X = Cl, Br, I; Y, Y' = S, Se, Te) are compared and discussed.