2,2′-Bis(methylene)-3,3′-(2-thioxo-2,3-dihydro-1H-benzimidazole-1,3-diyl)dipropanenitrile

In the title compound, C15H12N4S, the benzimidazole ring is essentially planar, with a mean deviation of 0.0082 (1) Å from the least-squares plane defined by the nine constituent atoms. In the crystal, inversion dimers linked by pairs of C—H⋯N hydrogen bonds occur.

In the title compound, C 15 H 12 N 4 S, the benzimidazole ring is essentially planar, with a mean deviation of 0.0082 (1) Å from the least-squares plane defined by the nine constituent atoms. In the crystal, inversion dimers linked by pairs of C-HÁ Á ÁN hydrogen bonds occur.

Related literature
Benzimidazole is a potential precursor in heterocyclic chemistry and the benzimidazol-2-thione ring is present in many pharmacologically active substances, see: Hwa et al. (2008). For ammonium salts from Mannich adducts as precursors for the synthesis of acrylic derivatives carrying functionalized thiomethyl groups, see: M'rabet et al. (2009). For a related structure, see: Khan et al. (2008). For bond-length data, see: Allen et al. (1987).  Table 1 Hydrogen-bond geometry (Å , ).
The bond lengths and angles in the structure of (I) ( Fig. 1) are in agreement with the corresponding bond lengths and angles reported for a compound closely related to (I) (Khan, H. et al., 2008) and are within normal ranges (Allen et al., 1987). The benzimidazole ring in (I) is essentially planar with a mean deviation of 0.0028 (1) Å from the least-squares plane defined by the nine constituent atoms. The molecular packing is stabilized by van der Waals interactions and intramolecular (C-H···S) and intermolecular (C-H···N) hydrogen bonds, which link the molecules into dimmers (Table 1 and Fig. 2).

Experimental
To a solution of ammonium salt (12 mmol) in ethanol (50 ml), was added dropwise with stirring 10 mmol of mercaptobenzimidazole. The reaction mixture was stirred for 24 h at room temperature. The residual salt was then filtered and the solvent was removed. The obtained residue was diluted with water (20 ml) and extracted with chloroform. The organic layer was dried over MgSO 4 and concentrated under reduced pressure. The product was chromatographed using a silica gel column with 60/40 ether/petroleum ether. The slow evaporation from the solvent afforded crystals of the title compound suitable for X-ray diffraction study.  Fig. 1. A perspective view of the molecule of (I) with displacement ellipsoids shown at the 30% probability level.

Data collection
Enraf-Nonius TurboCAD-4 diffractometer R int = 0.018 as those based on F, and R-factors based on ALL data will be even larger.