3-(4-Bromophenyl)-5-[4-(dimethylamino)phenyl]-4,5-dihydro-1H-pyrazole-1-carbothioamide

The molecule of the title pyrazole derivative, C18H19BrN4S, is twisted. The central pyrazole ring, which adopts a flattened envelope conformation, is almost coplanar with the 4-bromophenyl ring, whereas it is inclined to the 4-(dimethylamino)phenyl ring making dihedral angles of 1.68 (6) and 85.12 (6)°, respectively. The dihedral angle between the two benzene rings is 86.56 (6)°. The dimethylamino group is slightly twisted from the attached benzene ring [C—C—N—C torsion angles = 8.4 (2) and 8.9 (2)°]. In the crystal, molecules are linked by intermolecular N—H⋯S hydrogen bonds into chains along [20]. The crystal is further stabilized by C—H⋯π interactions.

The molecule of the title pyrazole derivative, C 18 H 19 BrN 4 S, is twisted. The central pyrazole ring, which adopts a flattened envelope conformation, is almost coplanar with the 4-bromophenyl ring, whereas it is inclined to the 4-(dimethylamino)phenyl ring making dihedral angles of 1.68 (6) and 85.12 (6) , respectively. The dihedral angle between the two benzene rings is 86.56 (6) . The dimethylamino group is slightly twisted from the attached benzene ring [C-C-N-C torsion angles = 8.4 (2) and 8.9 (2) ]. In the crystal, molecules are linked by intermolecular N-HÁ Á ÁS hydrogen bonds into chains along [210]. The crystal is further stabilized by C-HÁ Á Á interactions.

Comment
The pyrazole moiety is one of the core structures in a number of natural products (Xie et al., 2008). Numerous compounds which contain the pyrazole moiety are known to exhibit a wide range of biological properties such as antihypertensive (Mikhaylichenko et al., 2009), analgesic (Hall et al., 2008), anti-inflammatory (Bekhit et al., 2008), antipyretic (Souza et al., 2002), antimicrobial (Gadakh et al., 2010), hypoglycemic (Cottineau et al., 2002), sedative-hypnotic (Hoepping et al., 2007) and antitumor activities (Park et al., 2005). Our on going research on biological activities of pyrazole derivatives led us to synthesize the title compound by cyclization of the chalcone derivative (Ono et al., 2007) with excess thiosemicarbazide.
Herein we report the crystal structure of the title compound.
In the crystal structure ( Fig. 2), the molecules are linked by intermolecular N-H···S hydrogen bonds (Table 1) into chains along the [2 1 0] direction. The crystal is further stabilized by C-H···π interactions (Table 1).
The yellow solid of the title compound obtained after cooling of the reaction mixture was filtered off under vacuum. Pale yellow block-shaped single crystals of the title compound suitable for X-ray structure determination were recrystalized from acetone/ethanol (1:1 v/v) by slow evaporation of the solvent at room temperature after several days. M.p. 481-482 K.

Refinement
The amino H atoms were located in difference Fourier map and refined isotropically. The remaining H atoms were positioned geometrically and allowed to ride on their parent atoms, with d(C-H) = 0.93 Å for aromatic, 0.97 Å for CH 2 and 0.96 Å for CH 3 atoms. The U iso values were constrained to be 1.5U eq of the carrier atom for methyl H atoms and 1.2U eq for the supplementary materials sup-2 remaining H atoms. A rotating group model was used for the methyl groups. The highest residual electron density peak is located at 0.75 Å from Br1 and the deepest hole is located at 0.56 Å from Br1. Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids.