4-Phenyl-1H-imidazole-2(3H)-thione

In the asymmetric unit of the title compound, C9H8N2S, there are four symmetry-independent molecules (Z′ = 4). The geometrical features of these molecules are quite similar: in the normal probability plots the R 2 correlation factors for bond lengths and angles are generally around 0.95. The twist angles between the imidazole and phenyl rings (which are planar within 3σ) range from 9.0 (6) to 13.1 (5)°. In the crystal, pairs of independent molecules are joined by linear N—H⋯S and weak C—H⋯S hydrogen bonds, forming infinite ribbons, of the type ∼ABABAB∼ and ∼CDCDCD∼, propagating along [110]. Second-order hydrogen-bonded R 2 2(8) rings are formed via interweaving infinite C 2 2(8) chains.

In the asymmetric unit of the title compound, C 9 H 8 N 2 S, there are four symmetry-independent molecules (Z 0 = 4). The geometrical features of these molecules are quite similar: in the normal probability plots the R 2 correlation factors for bond lengths and angles are generally around 0.95. The twist angles between the imidazole and phenyl rings (which are planar within 3) range from 9.0 (6) to 13.1 (5) . In the crystal, pairs of independent molecules are joined by linear N-HÁ Á ÁS and weak C-HÁ Á ÁS hydrogen bonds, forming infinite ribbons, of the type $ABABAB$ and $CDCDCD$, propagating along [110]. Second-order hydrogen-bonded R 2 2 (8) rings are formed via interweaving infinite C 2 2 (8) chains.
These are mainly S-metal complexes and few simple organic derivatives, for instance 1,3-dihydro-2H-imidazole-2-thione hydrate (Raper et al., 1984) and 4-formyl-1,3-dihydro-2H-imidazole-2-thione (Conde et al., 1977). Overall conformation of the molecules can be described here by the dihedral angles between two almost perfectly planar (within 3 s.u.'s) rings, imidazole and phenyl. These angles are relatively small -thanks partially at least to the lack of the sterical hindrance -and range from 9.0 (6)° for molecule B to 13.1 (5)° for molecule C. The bond length and angles are typical, with the C-S bond distance confirming its double-bond character, the mean value of this length is 1.694 (4) Å.
In the crystal structure the pairs of molecules A-B and C-D create identical but independent motifs. They are joined into infinite ribbons (along [110]) by means of relatively short and linear N-H···S hydrogen bonds (Table 1, Fig. 2), and additionally by weaker, secondary C-H···S hydrogen bonds. Using graph-set notation (Etter, et al., 1990, Bernstein et al., 1995, one can identify the second-order rings R 2 2 (8) which are made by interweaving C 2 2 (8) chains. These almost independent ribbons combine together to make the overall three-dimensional structure (Fig. 3).

Experimental
The title compound was prepared by adding hydrochloric acid to acetonitrile solution of 4-phenyl-imidazole-2-thiol in molar ratio 1:1. After a few minutes colourless, thin crystals of 1, suitable for single-crystal X-ray analysis appeared and were filtered off.

Refinement
Hydrogen atoms were put in the idealized positions, and refined as riding model. Their isotropic thermal parameters were set at 1.2 times U eq 's of appropriate carrier atoms.   The hydrogen-bonded ribbon of molecules A and B (molecules C and D are joined into almost identical structure).

Computing details
Hydrogen bonds are shown as dashed lines, symmetry codes:; (i) -1/2 + x,-1/2 + y,z; (ii) 1/2 + x,1/2 + y,z..  The crystal packing as seen approximately along c-direction, hydrogen bonds are drawn as dashed lines. Symmetryindependent molecules are shown with different colours.  (13) Special details Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.