3-(4-Chlorophenyl)-5-(4-ethoxyphenyl)-4,5-dihydro-1H-pyrazole-1-carbothioamide ethanol monosolvate

The asymmetric unit of the title compound, C18H18ClN3OS·C2H5OH, comprises a pyrazoline derivative and an ethanol solvent molecule. In the molecule of the pyrazoline derivative, the pyrazole ring adopts an envelope conformation with the C atom bearing the ethoxyphenyl substituent as the flap. The dihedral angle between the benzene rings is 74.22 (7)°. The ethoxy group is coplanar with the attached benzene ring [C—O—C—Cmethyl = 175.50 (11)° and r.m.s. deviation = 0.0459 (1) Å for the nine non-H atoms]. In the crystal, the pyrazoline molecules are linked by N—H⋯Oethoxy hydrogen bonds into chains along the c axis and are further linked with the solvent ethanol molecules by N—H⋯Oethanol and Oethanol—H⋯S hydrogen bonds. C—H⋯π interactions are also present.

The asymmetric unit of the title compound, C 18 H 18 ClN 3 OSÁ-C 2 H 5 OH, comprises a pyrazoline derivative and an ethanol solvent molecule. In the molecule of the pyrazoline derivative, the pyrazole ring adopts an envelope conformation with the C atom bearing the ethoxyphenyl substituent as the flap. The dihedral angle between the benzene rings is 74.22 (7) . The ethoxy group is coplanar with the attached benzene ring [C-O-C-C methyl = 175.50 (11) and r.m.s. deviation = 0.0459 (1) Å for the nine non-H atoms]. In the crystal, the pyrazoline molecules are linked by N-HÁ Á ÁO ethoxy hydrogen bonds into chains along the c axis and are further linked with the solvent ethanol molecules by N-HÁ Á ÁO ethanol and O ethanol -HÁ Á ÁS hydrogen bonds. C-HÁ Á Á interactions are also present.
Data collection: APEX2 (Bruker, 2005); cell refinement: SAINT (Bruker, 2005); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL, PLATON (Spek, 2009) and publCIF (Westrip, 2010). The studies of pyrazoline derivatives have gained increasing interests in the therapeutic research field due to their broad spectrum of biological properties such as antihypotensive, muscle relaxant, anticonvulsant, psychoanaleptic and antidepressant activities (Bilgin et al., 1992;Bilgin et al., 1993;Bilgin et al., 1994;Gokhan et al., 2003;Ruhoglu et al., 2005). The previous studies by Bilgin and co-workers (Bilgin et al., 1993) reported the synthesis of thiocarbamoyl pyrazoline derivatives which exhibited significant antidepressant activity. Moreover pyrazoline derivatives with the phenyl group at the 5-position have been shown to exhibit excellent blue photoluminescence (Zhang et al., 2000). In view of the importance of pyrazoline derivatives, we have synthesized a series of thiocarbamoyl pyrazoline derivatives by the cyclization reaction between chalcones and thiosemicarbazide and have studied their fluorescence, antioxidant and antityrosinase activities. The title compound (I) was synthesized and evaluated for fluorescent property and antioxidant activity by DPPH scavenging (Molyneux, 2004). Unfortunately our results show that (I) did not exhibit fluorescence and was found to be inactive for antioxidant and antityrosinase activities. Herein we report the synthesis and crystal structure of (I).

Experimental
The title compound was synthesized by dissolving (E)-1-(4-chlorophenyl)-3-(4-ethoxyphenyl)prop-2-en-1-one (0.29 g, 1 mmol) in ethanol (10 ml) and the solution of an excess thiosemicarbazide (0.18 g, 2 mmol) in a solution of KOH (0.11 g, 2 mmol) in ethanol (15 ml) was then added. The reaction mixture was vigorously stirred and refluxed for 4 h. The pale yellow solid of the title compound was obtained after cooling of the reaction and was then filtered off under vacuum. Pale yellow block-shaped single crystals of the title compound suitable for X-ray structure determination were recrystallized from CH 3 OH/C 2 H 5 OH (1:1 v/v) by slow evaporation of the solvent at room temperature after several days. M. p.: 406-407 K.

Refinement
Amide and ethanol H atoms were located from difference Fourier maps 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, 1.00 Å for CH, 0.99 Å for CH 2 and 0.98 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 remaining H atoms. A rotating group model was used for the methyl groups.

Figure 1
The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom-numbering scheme.  The crystal packing of the title compound viewed along the a axis. Only H atoms involved in hydrogen bonding were shown for the sake of clarity. Hydrogen bonds were drawn as dashed lines.   (Cosier & Glazer, 1986) operating at 120.0 (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.