4-Chlorobenzothioamide

In the title compound, C7H6ClNS, the dihedral angle between the aromatic ring and the thioamide fragment is 28.1 (2)°. The structure features a π-stacking interaction between the aromatic rings with a slight offset of the rings, giving a centroid–centroid separation of 3.7942 (2) Å. There are intermolecular hydrogen-bonding interactions between the amino group and the S atoms.

In the title compound, C 7 H 6 ClNS, the dihedral angle between the aromatic ring and the thioamide fragment is 28.1 (2) . The structure features a -stacking interaction between the aromatic rings with a slight offset of the rings, giving a centroid-centroid separation of 3.7942 (2) Å . There are intermolecular hydrogen-bonding interactions between the amino group and the S atoms.
MuHK is thankful to the HEC, Pakistan, for a PhD fellowship under the indigenous PhD Program. JDM thanks Saint Mary's Univeristy for funding.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: BT2933).

Comment
Thioamides are important precursors/intermediates in the synthesis of various heterocycles (Jagodzinski et al., 2003). Besides being used as synthetic intermediates, they exhibit numerous biological activities (Wei et al., 2006). In addition, thioamides have found use as important ligands in coordination chemistry (Lebana et al., 2008). Several methods for their synthesis have been published involving the uses of Lawesson's regent (Cava et al., 1985) and phosphorus pentasulphide (Bauer et al., 1985). The title compound, 4-chlorobenzothioamide was synthesized in continuation of our previous work on the synthesis and biological screenings of five membered heterocycles (Akhtar et al., 2006(Akhtar et al., , 2007(Akhtar et al., , 2008. In this article the crystal structure of 4-chlorobenzothioamide is being reported. The title compound was synthesized by treating 4-chlorobenzonitrile with 70% sodium hydrogen sulfide hydrate and magnesium chloride hexahydrate in dimethylformamide (Manaka & Sato, 2005) as an intermediate for the synthesis of thiazoles.
The hydrogen bonding interactions between the nitrogen and sulfur atoms are in the range of those seen in p-trifluoromethylbenzothioamide where the corresponding interactions are between 3.3735Å and 3.5133Å (Jian et al., 2006).
Experimental 4-Chlorobenzonitrile (14.5 mmol) was added to a slurry of sodium hydrogen sulfide hydrate (70%, 29 mmol) and magnesium chloride hexahydrate (14.5 mmol) in DMF (40 mL) and the mixture stirred at room temperature for 2 h. The resulting green slurry was poured into water (100 mL) and the precipitated solid collected by filtration. The product obtained was resuspended in 1 N HCl (50 ml), stirred for another 30 min, filtered and washed with excess of water. The recrystallization of the residue from chloroform afforded the crystals of the title compound suitable for X-ray analysis.

Refinement
The hydrogen atoms were placed in geometrically idealized positions of 0.93Å (aromatic C-H) and 0.86Å (amide N-H) and constrained to ride on the parent atom with U iso (H) = 1.2 U eq (C,N).   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 Rfactors(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.