3-[3-(3-Fluorophenyl)-1,2,4-oxadiazol-5-yl]propionic acid

In the title compound, C11H9FN2O3, the benzene ring is almost coplanar with the heterocyclic ring, making a dihedral angle of 14.0 (1)°. The plane of the carboxyl group is rotated by 14.7 (3)° with respect to the 1,2,4-oxadiazole ring plane. The aliphatic chain exhibits a standard zigzag arrangement. Two intermolecular O—H⋯O hydrogen bonds between the carboxyl groups related by an inversion centre promote a dimeric structure formation. The dimers are stacked along the crystallographic a axis.

In the title compound, C 11 H 9 FN 2 O 3 , the benzene ring is almost coplanar with the heterocyclic ring, making a dihedral angle of 14.0 (1) . The plane of the carboxyl group is rotated by 14.7 (3) with respect to the 1,2,4-oxadiazole ring plane. The aliphatic chain exhibits a standard zigzag arrangement. Two intermolecular O-HÁ Á ÁO hydrogen bonds between the carboxyl groups related by an inversion centre promote a dimeric structure formation. The dimers are stacked along the crystallographic a axis.

Structure Reports Online
In the title compound ( Fig. 1), the bond lengths and angles are in agreement with the values previously reported for 1,2,4-oxadiazole-containing molecules (Wang et al., , 2007Yan, Xing et al., 2006;Yan et al., 2006a,b). The torsion angle N2-C3-C11-C16 between the benzene ring attached to C-3 of the 1,2,4-oxadiazole system is -13.6 (2)°, thus, both rings are almost coplanar. The C-5 side-chain containing a carboxylic acid group shows a zigzag arrangement, having the torsion angle C5-C6-C7-C8 of -179.4 (1)°. In addition, the plane of the carboxylic group is also rotated by 14.7 (3)°w ith respect to the mean plane of the 1,2,4-oxadiazole five-membered ring, but in opposite direction of deviation of the fluoro-phenyl ring. This makes the molecular structure to be slightly twisted. Carboxylic groups are involved in centrosymmetric intermolecular hydrogen-bonding forming a dimeric structure (Fig. 2). The dimmers are perfectly stacked along the crystallographic a axis (Fig. 3).

Experimental
The title compound was synthesized following the procedure reported earlier for the analogous compounds (Srivastava & Seabra, 1997;Sindkhedkar et al., 2008). A mixture of 3-fluorbenzamidoxime (2.0 mmol) and succinic anhydride (2.2 mmol) was heated in a domestic microwave oven for 10 min. The crude material was purified by column chromatography.
Crystallization of pure material from chloroform, from which a suitable crystal was chosen for the X-ray crystallographic experiment.

Refinement
H atoms attached to C atoms were added at their calculated positions and included in the structure factors calculations, with C-H = 0.93 (aromatic) and 0.97 Å (methylene), and with U iso (H) = 1.2U eq (C). The H atom of carboxylic acid was located in a difference Fourier map and treated as a free atom. Fig. 1. The molecular structure of (I) with labeling scheme. Displacement ellipsoids are shown at the 40% probability level.