3-Nitrobenzonitrile

3-Nitrobenzonitrile crystallizes in the Sohncke space group P21.

The crystal structure of 3-nitrobenzonitrile, C 7 H 4 N 2 O 2 , was elucidated by lowtemperature single-crystal X-ray diffraction.The compound crystallizes in the Sohncke space group P2 1 and features two molecules in the unit cell.Aromatic �-� stacking leads to stacks of molecules in the [100] direction.The absolute structure was established from anomalous dispersion.

Structure description
3-Nitrobenzonitrile crystallizes in the monoclinic Sohncke space group P2 1 with one molecule in the asymmetric unit (Fig. 1).The nitro group is not coplanar with the benzene ring, but slightly tilted.The corresponding angle between the benzene ring and NO 2 plane normals is 11.22 (6) � with atom O1 located 0.163 (3) A ˚below and atom O2 0.253 (3) A ˚above the plane of the benzene ring.
This tilt of the NO 2 group is presumably the result of the crystal packing, which locks the orientation of the NO 2 group.The corresponding non-coplanar orientation of the NO 2 group induces the asymmetry of the molecule and, in turn, the chirality of the crystal.In solution, where the barriers for the rotation of the nitro group are usually low, for instance, 19 kJ mol À 1 in nitrobenzene determined by gas-phase electron diffraction (Borisenko & Hargittai, 1996), the rotation is not hindered, and the molecule can readily adopt different conformations.
The C-C and C-H bonds of the benzene ring span the ranges 1.3851 (19)-1.397(2) A ˚and 0.91 (3)-0.96(2) A ˚, respectively.The substituents are bonded to the benzene ring by a C-N bond of 1.4697 (19) A ˚in the case of the nitro group and a C-C bond of 1.447 (2) A ˚in the case of the nitrile group.The observed N-O distances of the nitro group are essentially equal [1.2258 (17) and 1.2262 (18) A ˚].The length of the C N triple bond in the nitrile group is 1.141 (2) A ˚.In the crystal (Fig. 2), the molecules are �-stacked along the shortest crystallographic axis, a, with an interplanar distance of 3.3700 (9) A ˚. Of the three positional isomers of nitrobenzonitrile, only the crystal structure of 4-nitrobenzonitrile has been previously reported (Cambridge Structural Database refcode PNBZNT; Higashi & Osaki, 1977).It also crystallizes in the Sohncke space group P2 1 and the tilt angle of the nitro group out of the benzene ring plane (10.3 � ) is similar to the angle reported herein for the meta isomer [11.22 (6) � ].

Synthesis and crystallization
The title compound was obtained by decomposition of the corresponding diazonium salt in ethanol.The diazonium salt was synthesized by the previously published procedure (Mihelac ˇet al., 2021).p-Toluenesulfonic acid monohydrate (570.7 mg; 3 mmol) was dissolved in 15 mL of ethyl acetate and 2-amino-5-nitrobenzonitrile (489.3 mg; 3 mmol) was added to the solution.The dropwise addition of tert-butyl nitrite (1068 mL, 9 mmol) resulted in the formation of a yellow solution, which was stirred for 5 minutes at room temperature.The yellow precipitate of 2-cyano-4-nitrobenzenediazonium tosylate was obtained by filtration and washed thoroughly with ethyl acetate.This solid was then dissolved in 10 mL of EtOH and stirred for 3 days at room temperature.3-Nitrobenzonitrile was isolated by filtration as an off-white solid.Single crystals were grown from a concentrated ethanol solution at À 20 � C. A crystal suitable for single-crystal X-ray data reports  The molecular structure of the title compound showing 50% displacement ellipsoids.Hydrogen atoms are depicted as spheres of arbitrary radius.diffraction analysis was selected under a polarizing microscope and mounted on a MiTeGen Dual Thickness MicroLoop LD using Baysilone-Paste (Bayer-Silicone, mittelviskos).

Refinement
Crystal data, data collection, and structure refinement details are summarized in Table 1.The positions of the hydrogen atoms were freely refined, including their isotropic displacement parameter U (Cooper et al., 2010)

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.

Table 1
Experimental details.