1H-Benzimidazole-2(3H)-thione

The asymmetric unit of the title compound, C7H6N2S, contains one half-molecule; the C and S atoms of the C=S group lie on a crystallographic mirror plane. In the crystal structure, intermolecular N—H⋯S hydrogen bonds link the molecules.

The asymmetric unit of the title compound, C 7 H 6 N 2 S, contains one half-molecule; the C and S atoms of the C S group lie on a crystallographic mirror plane. In the crystal structure, intermolecular N-HÁ Á ÁS hydrogen bonds link the molecules.

Comment
It is a kind of secondary age inhibitor, and could reinforce the effect combined with DNP AP and other nonpolluting age inhibitors. It disperses easily in rubber, and the color does not change under sun exposure. Its pollution capacity is limited.
2-Mercaptobenzimidiazole is a new kind of anti-leprosy drugs, and its toxicity is lower than sulphone drugs. It should not be used in the patients to which can not be given sulphone drugs. We report herein the crystal structure of the title compound.
The asymmetric unit of the title compound ( Fig. 1) contains one-half molecule, in which a mirror plane passes through S and C4 atoms. The bond lengths (Allen et al., 1987) and angles are within normal ranges.
In the crystal structure, intermolecular N-H···S hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental
For the preparation of the title comppund, 1,2-diaminobenzene (0.019 mol) and water (3 ml) were added to a solution of sodium hydroxide (0.022 mol) in ethanol (20 ml) and carbon disulfide (0.022 mol). The mixture was heated under reflux for 3 h. Charcoal was added cautiously and removed by filtration after the mixture has been refluxed for 10 min more. The filtrate was heated to 377 K and quenched with warm water (377 K, 20 ml), and then acetic acid (9 ml) was added by stirring.
The product was separated and after cooling in refrigerator for 3 h the crystallization was completed (Mavrova et al., 2007).
Crystals suitable for X-ray analysis were obtained by slow evaporation of an ethanol solution after two weeks.

Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH) and C-H = 0.93 Å for aromatic H and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C,N). Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.