2-Thioureido-1H-benzimidazol-3-ium chloride monohydrate

In the title compound, C8H9N4S+·Cl−·H2O, the cation is approximately planar, with a dihedral angle of 7.71 (8)° between the mean planes of the benzoimidazole ring system and the thiourea unit. In the crystal, cations, anions and water molecules of crystallization are linked by O—H⋯Cl, N—H⋯O, N—H⋯Cl and N—H⋯S hydrogen bonds into a three-dimensional network. π–π stacking is observed between the benzene and imidazole rings of neighbouring molecules, the centroid–centroid distance being 3.5774 (11) Å.


Comment
In recent years, Benzimidazole moiety has gained increased interest in drug industry worldwide, as an important pharmocophore exhibiting a wide spectrum of biological and pharmaceutical activities. They act as anti-HIV agents, anti cancer agents (Refaat, 2010), anti-tumor agents (Starcevic et al., 2007), anti-microbial agents (Puratchikody et al., 2008) analgesic and anti-inflammatory agents (Achar et al., 2010).
The title compound ( Fig. 1), C 8 H 11 ClN 4 OS, crystallized in monoclinic P2 1 /c space group with Z=4 ( Fig. 2). Two chloride anions and two water molecules are acting as a bridge to connect four molecules of the title compound which resulted in infinite layered type supramolecular architecture. The title compound is mainly stabilized by N-H···O, N-H···Cl, O-H···Cl intermolecular hydrogen bonding which resulted in generating of ring motifs R 2 2 (8) and R 1 2 (6). The intramolecular ring motif S 1 1 (6) is also generated due to intramolecular N-H···S hydrogen bonding.

Experimental
A mixture of 5-amino-3H-1, 2, 4-dithiazole-3-thione (1.5 g, 0.01 mol) and o-phenylenediamine (1.08 g, 0.01 mol) in absolute ethanol (25 ml) was refluxed for 24 h. The solvent was removed under reduced pressure and the residue was treated with aqueous sodium hydroxide (1 N, 3 × 20 ml) and then filtered after an hour. The filtrate was adjusted to pH 5 by addition of aqueous hydrochloric acid (1 N) and left in a refrigerator overnight. The precipitate (1.8 g, 74%) was collected, washed with water and dried. The title compound was recrystallized from formic acid-propanol mixture to yield small crystals. The melting point was recorded as 248-251°C.

Refinement
The structure refinements were performed by full-matrix least-squares on F2. The H positions bound to C atoms were calculated after each cycle of refinement using a riding model C-H = 0.93 Å and U iso (H) = 1.2U eq (C). H atoms bound to N and O atoms were located in a difference Fourier map and refined in riding mode, U iso (H) = 1.2U eq (N) and 1.5U eq (O).  Crystal packing diagram of the title compound (I).

Figure 3
Synthetic scheme of the title compound (I). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.25 e Å −3 Δρ min = −0.20 e Å −3 Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > σ(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.