The crystal structure of Cr 1.73Mo 6S 8

Abstract

Single crystals of Cr 1.73Mo 6S 8 with triclinic symmetry were grown from a melt of an appropriate mixture of Mo 2S 3, molybdenum and chromium. A single crystal structure determination was performed in space group P 1 (C i 1, No. 2; R(F 0) = 0.032 ) including 2870 reflections with No. 2; R(F 0) = 0.032) including 2870 reflections with F 0 2>2 δ( F 0 2). The lattice parameters are: a = 652.2(2) pm, b = 649.7(2) pm, c = 644.9(1) pm, a = 94.68(2)°, β = 90.70(2)°, γ = 97.91(2)δ (Guinier data). The structure is isopointal with Fe 2Mo 6S 8. The chromium atoms are located in parallel channels [010] Fe 2Mo 6S 8. The chromium atoms are located in parallel channels [010] which are surrounded by Mo 6S 8 clusters linked via six intercluster Mo-S contacts. The coordination about the chromium atoms and the Cr-S distances are in accordance with the valence state +2 for chromium. Despite the low rotational symmetry the refinements indicate some disorder of the chromium atoms which is not resolved by releasing the centre of symmetry. In addition, indications of a lowering of translational symmetry do not exist.