(E)-3-(3-Chlorophenyl)-1-(4-methoxyphenyl)prop-2-en-1-one

The title molecule, C16H13ClO2, is trans with respect to the C=C double bond. The dihedral angles between the mean plane of the prop-2-en-1-one unit and those of the 3-chloro- and 4-methoxy-substituted benzene rings are 20.93 (9) and 20.42 (10)°, respectively, and the dihedral angle between the mean planes of the two benzene rings is 40.96 (5)°. The crystal structure is stabilized by weak intermolecular C—H⋯O hydrogen bonds, forming chains along the b axis.

The title molecule, C 16 H 13 ClO 2 , is trans with respect to the C C double bond. The dihedral angles between the mean plane of the prop-2-en-1-one unit and those of the 3-chloroand 4-methoxy-substituted benzene rings are 20.93 (9) and 20.42 (10) , respectively, and the dihedral angle between the mean planes of the two benzene rings is 40.96 (5) . The crystal structure is stabilized by weak intermolecular C-HÁ Á ÁO hydrogen bonds, forming chains along the b axis.
The title molecule ( Fig. 1) exhibits an E configuration with respect to the C═C double bond, the torsion angle C-C═C-C being -177.75 (17)°. The dihedral angle between the mean planes of the 3-chloro and 4-methoxy substituted benzene rings is 40.96 (5)°. The dihedral angles between the mean planes of the prop-2-en-1-one unit and those of the 3-chloro and 4-methoxy substitued benzene rings are 20.93 (9) and 20.42 (10)°, respectively. The geometrical parameters for (I) are consistent with those of some recently reported chalcone derivatives closely related to (I) (Rosli et al., 2006;Patil et al., 2006;Harrison et al., 2006;Fun et al.;2008;Jasinski et al., 2010). The structure is stabilized by intermolecular interactions of the type C-H···O resulting in polymeric chains along the b-axis (Fig. 2, Tab. 1) Experimental A mixture of 3-chlorobenzaldehyde (0.01 moles, 1.13 g), 4-methoxyacetophenone (0.01 moles, 1.37 ml) and sodium hydroxide solution (10%, 30 ml) was stirred at room temperature for 6 hrs. Precipitates obtained were poured into ice-cold water (500 ml) and left to stand for 2 hours followed by filtration of the resultant solid which was dried and crystallized from ethanol by slow evaporation.

Refinement
The H-atoms were clocated from difference Fourier maps and were included in the refinement at geometrically idealized positions in riding-model approximation with C-H = 0.95 and 0.98 Å for aryl and methyl type H-atoms, respectively; the U iso (H) were allowed at 1.2U eq (C). The final difference map was essentially featurless. Fig. 1. The title molecule plotted with the displacement ellipsoids at 50% probability level (Farrugia, 1997

Special details
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 > 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.