5-(2,4-Dichlorophenyl)-3-(4-nitrophenyl)-1,2,4-oxadiazole

In the title compound, C14H7Cl2N3O3, the dichlorophenyl and nitrophenyl rings form dihedral angles of 5.4 (2) and 4.0 (2)°, respectively, with the oxadiazole ring. The nitro group is twisted out of the attached benzene ring by a dihedral angle of 10.4 (3)°. In the crystal, molecules are linked into a chain along the a axis by C—H⋯N hydrogen bonds.

In the title compound, C 14 H 7 Cl 2 N 3 O 3 , the dichlorophenyl and nitrophenyl rings form dihedral angles of 5.4 (2) and 4.0 (2) , respectively, with the oxadiazole ring. The nitro group is twisted out of the attached benzene ring by a dihedral angle of 10.4 (3) . In the crystal, molecules are linked into a chain along the a axis by C-HÁ Á ÁN hydrogen bonds.

Comment
Heterocyclic compounds are becoming increasingly important in recent years due to their pharmacological activities . Nitrogen-and oxygen-containing five/six-membered heterocyclic compounds are of enormous significance in the field of medicinal chemistry (Chandrakantha et al., 2010). Oxadiazoles play a very vital role in the preparation of various biologically active drugs with anti-inflammatory (Andersen et al., 1994), anti-cancer (Showell et al., 1991), anti-HIV (Watjen et al., 1989, anti-diabetic and anti-microbial (Swain et al., 1991) activities. The results of biological studies showed that oxadiazole derivatives also possess maximum anti-inflammatory, analgesic and minimum ulcerogenic and lipid per-oxidation (Clitherow et al., 1996) properties.
In the crystal structure (Fig. 2), the molecules are connected by intermolecular C13-H13A···N1 hydrogen bonds (Table   1) forming chains along the a axis.

Refinement
H atoms were positioned geometrically with C-H = 0.93 Å and were refined using a riding model with U iso (H) = 1.2U eq (C).

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 > 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.