1-[3-(4-Chlorophenyl)-5-(4-methoxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl]ethanone

In the title compound, C18H17ClN2O2, the benzene rings form dihedral angles of 6.69 (6) and 74.88 (5)° with the 4,5-dihydro-1H-pyrazole ring. The benzene rings form a dihedral angle of 76.67 (5)° with each other. In the crystal, molecules are linked via bifurcated (C,C)–H⋯O hydrogen bonds into chains along [010]. The crystal structure is further consolidated by C—H⋯π interactions.

In the title compound, C 18 H 17 ClN 2 O 2 , the benzene rings form dihedral angles of 6.69 (6) and 74.88 (5) with the 4,5-dihydro-1H-pyrazole ring. The benzene rings form a dihedral angle of 76.67 (5) with each other. In the crystal, molecules are linked via bifurcated (C,C)-HÁ Á ÁO hydrogen bonds into chains along [010]. The crystal structure is further consolidated by C-HÁ Á Á interactions.

Related literature
For general background to and the biological activity of the title compound, see: Samshuddin et al. (2011);Sarojini et al. (2010). For standard bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used in the the data collection, see: Cosier & Glazer (1986). For a related structure, see: Fun et al. (2010).  Table 1 Hydrogen-bond geometry (Å , ).

Experimental
Cg1 is the centroid of C10-C15 benzene ring.

Refinement
All H atoms were positioned geometrically and refined using a riding model with C-H = 0.95 or 1.00 Å and U iso (H) = 1.2 or 1.5 U eq (C). A rotating group model was applied to the methyl groups.

Figure 2
The crystal structure of the title compound, viewed along the c axis. H atoms not involved in hydrogen bonds (dashed lines) have been omitted for clarity.

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.