N-(4-Cyanophenyl)-2,6-difluorobenzamide

In the title compound, C14H8F2N2O, the amide plane is inclined at dihedral angles of 28.12 (12) and 32.89 (12)° with respect to the two benzene rings; the dihedral angle between the two rings is 5.58 (5)°. In the crystal, intermolecular N—H⋯O and C—H⋯F hydrogen bonds link adjacent molecules into a double-chain structure along the b axis.

In the title compound, C 14 H 8 F 2 N 2 O, the amide plane is inclined at dihedral angles of 28.12 (12) and 32.89 (12) with respect to the two benzene rings; the dihedral angle between the two rings is 5.58 (5) . In the crystal, intermolecular N-HÁ Á ÁO and C-HÁ Á ÁF hydrogen bonds link adjacent molecules into a double-chain structure along the b axis.

Related literature
For general background to and applications of the title compound, see: Ashwood et al. (1990); Kees et al. (1989); Ragavan et al. (2010); Carmellino et al. (1994); Rauko et al. (2001). For a closely related benzamide structure, see: Cronin et al. (2000). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 Table 1 Hydrogen-bond geometry (Å , ).  ities. On the basis of these considerations, our particular attention was paid for the synthesis of some benzamide derivatives.

Experimental
A mixture of 4-amino benzonitrile (4.2 mmol), 2,6-difluorobenzoic acid (4.6 mmol) and triethyl amine (21 mmol) was dissolved in methylene dichloride (5 ml). The resulting solution was cooled to 273 K followed by the drop wise addition of 50 % phosphoric acid cyclic anhydride solution in ethyl acetate (4 ml, 6.3 mmol) and stirred for 12 h. The completion of reaction was checked by TLC. Evaporation of solvent gave 2,6-difluoro-N-(p-cyanophenyl)benzamide as solid mass, which was then stirred with saturated NaHCO 3 solution to remove excess of acid. Single crystals suitable for X-ray analysis were obtained by crystallization from acetone under slow evaporation. M.p. 418 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.