Crystal structure and molecular motion of solid carbon disulfide

The crystal structure of CS₂ was determined at two temperatures from intensity data measured with a proportional counter and a modified Weissenberg apparatus. The orthorhombic cell [(a) 6.3437(8), (b) 5.5244(4), (c) 8.9971(7), 143°K, Cmca, Z=4] exhibited marked anisotropic thermal expansion, the coefficients of thermal expansion being α_a= 630×10^-5 °C^-1, α_b= 570×10^-6 °C^-1 α_c=- 630×10^-5 °C^-1. Positional and anisotropic thermal parameters were refined using upper-angle data (sinθ/ λ≥0.35) and the x-ray results were compared with data from spectroscopic sources on the molecular motion of CS₂ in the solid. The unweighted reliability indices for the two refinements were 0.039(148°K) and 0.056(133°K). The carbon-sulfur bond length corrected for foreshortening due to libration was 1.560(3) Å (133°K) and 1.559 Å (148°K), in agreement with calculations of the length in the gas from spectral data (1.558±0.0005) and electron diffraction (1.559±0.002).