Crystal structure of 1,3-dimethylimidazole-2(3H)-thione (C5H8N2S)

Abstract

The structure of the title compound has been established by X-ray crystallography from diffractometer data. Crystals are orthorhombic, space group either Bmmb or Bm2₁b, Z= 4, with cell dimensions: a= 8·475 ± 0·002, b= 6·826 ± 0·003, c= 11·206 ± 0·005 Å.

In space group Bmmb, 195 observable reflections were refined to R 0·028. The molecule has mm symmetry. The C–S distance and bond lengths within the five membered ring clearly indicate that (Ib) is the major contributor to the resonance hybrid (Ic). The planar molecules are stacked along the b axis with a perpendicular separation of 3·413 Å. All intermolecular distances appear to be van der Waals separations. The model was investigated for the effects of thermal motion on bond lengths. The corrections were of the order of the estimated standard deviations for the corresponding bonds.

In space group Bm2₁b refinement stops at R 0·027. The molecule has m(pseudo-m) symmetry and differs only very slightly from the previous model. There are small changes in thermal parameters (particularly for hydrogen) and the methyl group is twisted very slightly so as not to lie symmetrically above, below, and in the plane formed by the heavy atoms. The ring hydrogens also deviate slightly from this plane.