Isonicotinonitrile–benzoic acid (1/1)

In the title 1:1 adduct, C6H4N2·C7H6O2, the carboxyl group and its attached phenyl ring are essentially coplanar, being twisted from each other by a dihedral angle of only 2.05 (3)°. In the crystal, the molecules are connected via O—H⋯N and C—H⋯O hydrogen bonds, building an R 2 2(7) ring. Molecules are further linked through π–π interactions [centroid–centroid distance of 3.8431 (8) and 3.9094 (8) Å], leading to a one-dimensional chain parallel to the b axis.

In the title 1:1 adduct, C 6 H 4 N 2 ÁC 7 H 6 O 2 , the carboxyl group and its attached phenyl ring are essentially coplanar, being twisted from each other by a dihedral angle of only 2.05 (3) . In the crystal, the molecules are connected via O-HÁ Á ÁN and C-HÁ Á ÁO hydrogen bonds, building an R 2 2 (7) ring. Molecules are further linked throughinteractions [centroid-centroid distance of 3.8431 (8) and 3.9094 (8) Å ], leading to a onedimensional chain parallel to the b axis.

Related literature
For related structures, see: Chen et al. (2009) ;Fu et al. (2008). For hydrogen-bonding motifs, see: Bernstein et al. (1995); Etter et al. (1990).  Table 1 Hydrogen-bond geometry (Å , ). isonicotinonitrile, its interaction with various acids has been studied and we have elaborated a serie of new materials with this organic molecule. In this paper, we describe the crystal structure of the title compound, isonicotinonitrile benzoate.

Experimental
The asymmetric unit is composed of a discrete isonicotinonitrile and benzoic acid molecules (Fig.1). The carboxyl and its parent phenyl ring are essentially coplanar, and only twisted from each other by a dihedral angles of 2.05 (3)°. The two molecules are nearly planar and are only slightly twisted by a dihedral angle of 1.87 (7)° . The molecules were connected via O-H···N and C-H···O hydrogen bonds building a R 2 2 (7) ring (Etter et al., 1990;Bernstein et al., 1995) which play an important role in stabilizing the structural conformation. The molecules units are further linked by weak offset π···π interactions leading to a one-dimensional chain parallel to the b axis (Table 2 and Fig. 2).

Experimental
The commercial isonicotinonitrile and benzoic acid (1/1 mol rate) were dissolved in water/methanol (5:3 v/v) solution. The solvent was slowly evaporated in air affording colourless block-shaped crystals of the title compound suitable for X-ray analysis.
While the permittivity measurement shows that there is no phase transition within the temperature range (from 100 K to 400 K), and the permittivity is 5.9 at 1 MHz at room temperature.

Refinement
All H atoms attached to C atoms were positioned geometrically and treated as riding, with C-H = 0.93 Å and U iso (H) = 1.2U eq (C) and the H atoms of carboxyl O located in difference Fourier maps and freely refined. In the last stage of refinement they were treated as riding on the O atom, with U ĩso (H) = 1.5U eq (O). Fig. 1. A view of the title compound with the atomic numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.

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.