3-(4-Chlorophenyl)-5-(thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide

In the title pyrazoline derivative, C14H12ClN3S2, the thiophene ring is disordered over two orientations with a refined site-occupancy ratio of 0.832 (4):0.168 (4). The pyrazoline ring adopts an envelope conformation with the C atom linking the thiophene ring at the flap. The dihedral angles between the benzene ring and the major and minor components of the thiophene ring are 88.6 (3) and 85.6 (15)°, respectively while the dihedral angle between the disorder components of the ring is 3.1 (16)°. The mean plane of the pyrazoline ring makes dihedral angles of 11.86 (13), 80.1 (3) and 83.0 (15)°, respectively, with the benzene ring, and the major and minor components of the thiophene ring. An intramolecular N(amide)—H⋯N(pyrazoline) hydrogen bond generates an S(5) ring motif. In the crystal, molecules are linked by weak C—H⋯S and N(amide)—H⋯S interactions into a tape along [10]. C—H⋯π interactions are also observed.

In the title pyrazoline derivative, C 14 H 12 ClN 3 S 2 , the thiophene ring is disordered over two orientations with a refined siteoccupancy ratio of 0.832 (4):0.168 (4). The pyrazoline ring adopts an envelope conformation with the C atom linking the thiophene ring at the flap. The dihedral angles between the benzene ring and the major and minor components of the thiophene ring are 88.6 (3) and 85.6 (15) , respectively while the dihedral angle between the disorder components of the ring is 3.1 (16) . The mean plane of the pyrazoline ring makes dihedral angles of 11.86 (13), 80.1 (3) and 83.0 (15) , respectively, with the benzene ring, and the major and minor components of the thiophene ring. An intramolecular N(amide)-HÁ Á ÁN(pyrazoline) hydrogen bond generates an S(5) ring motif. In the crystal, molecules are linked by weak C-HÁ Á ÁS and N(amide)-HÁ Á ÁS interactions into a tape along [101]. C-HÁ Á Á interactions are also observed.

Comment
The synthesis of pyrazoline derivatives which contain 5-membered heterocyclic structure have attracted a lot of interests in many fields, for example as in medicinal chemistry owing to their biological properties such as antiamoebic (Husain et al., 2008), anti-inflammatory (Shoman et al., 2009), analgesic (Khode et al., 2009) and antioxidant (Taj et al., 2011) activities, as well as in fluorescence (Bai et al., 2007;Gong et al., 2011) studies. Our on-going research on biological activities and fluorescent property of pyrazoline derivatives has led us to synthesize the title compound (I) in order to compare its biological activity with the related compounds Nonthason et al., 2011).

Experimental
The title compound was synthesized by dissolving (E)-1-(4-chlorophenyl)-3-(2-thienyl)prop-2-en-1-one (0.25 g, 1.0 mmol) in a solution of KOH (0.06 g, 1.0 mmol) in ethanol (20 ml). An excess thiosemicarbazide (0.14 g, 1.5 mmol) in ethanol (20 ml) was then added, and the reaction mixture was vigorously stirred and refluxed for 4 h. The pale-yellow solid of the title compound obtained after cooling of the reaction was filtered off under vacuum. Pale yellow needle-shaped single crystals of the title compound suitable for X-ray structure determination were recrystalized from CH 3 OH/CH 2 Cl 2 (1:1 v/v) by slow evaporation of the solvent at room temperature after several days.

Refinement
Amide H atoms were located in a difference map and refined isotropically. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.95 Å for aromatic and 0.99 Å for CH 2 atoms. The supplementary materials sup-2 U iso values were constrained to be 1.2U eq of the carrier atoms. The thiophene ring is disordered over two positions with the refined site-occupancy ratio of 0.832 (4):0.168 (4). In the final refinement, distances restraint was used. The highest residual electron density peak is located at 1.35 Å from Cl1 and the deepest hole is located at 0.52 Å from Cl1. The crystal was a pseudo-merohedral twin and the structure was refined with the twin law (-1 0 0 0 -1 0 0 0 1). The BASF was refined to 0.138 (1). Fig. 1. The molecular structure of the title compound, showing 45% probability displacement ellipsoids and the atom-numbering scheme. Open bond show the minor B component. Intramolecular N-H···N hydrogen bond was shown as dash line. 3-(4-Chlorophenyl)-5-(thiophen-2-yl)-4,5-dihydro-1H-pyrazole-1-carbothioamide

Special details
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K.
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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.