The crystal structures of the hexachloroantimonate salts of (CH3)2SS(CH3)+, (CH3S)3+, and (CH3Se)3+

Abstract

The crystal structures of [(CH₃)₂SS(CH₃)]SbCl₆(1), [(CH₃S)₃]SbCl₆(2), and [(CH₃Se)₃]SbCl₆(3) have been determined by X-ray crystallography at 170 K. Compound (1) is triclinic, space group P with a= 701.3(3), b= 1 415.1(8), c= 689.9(3) pm, α= 94.97(4), β= 91.19(4), γ= 91.43(4)°, Z= 2. Though (2) and (3) are analogous to each other and both are monoclinic, space group P2₁/c, they are not isomorphous. For (2), a= 1 395.3(4), b= 928.9(3), c= 1 145.2(4) pm, β= 94.31(3)°, Z= 4; for (3), a= 701.8(4), b= 1 970.7(9), c= 1 197.8(5) pm, β= 113.45(4)°, Z= 4. Each cation involves a three-co-ordinated chalcogen atom. The S–S bond length in (1) is relatively long while in (2) and (3) the chalcogen–chalcogen bonds have almost normal single bond lengths. (CH₃)₂SS(CH₃)⁺ has an all-cis conformation with the approximate site symmetry C_s. The conformations of (CH₃S)₃⁺ and (CH₃Se)₃⁺ are fairly similar with the chain-end methyl groups in trans positions to each other. The packing of the ions is, however, different. This is also reflected by the drastically differing colours of these two compounds, (2) is practically colourless while (3) is deep red. In all three compounds the SbCl₆^– anion is almost a regular octahedron with Sb–Cl 236.1(1)–239.3(4) pm and Cl–Sb–Cl 88.4(1)–91.1(1)°. The Raman spectra of (2) and (3) are reported.