4-(4-Nitrobenzyl)pyridine

The title compound, C12H10N2O2, has a twisted conformation, with a dihedral angle between the planes of the pyridine and benzene rings of 78.4 (2)°. The nitro group is coplanar with the attached benzene ring within experimental error. The molecules form centrosymmetric dimers via Car—H⋯O interactions (H⋯O = 2.49 Å) and the dimers are π-stacked along the b axis [the separation between ring centroids is 3.788 (2) Å].

The title compound ( Fig. 1) gives colorless crystals. The angle between the planes of benzene and pyridine rings is 78.43° and the nitro group is coplanar with the benzene ring. The two aromatic planes are twisted relative to each other, which result in reduction of molecular symmetry from C s to C 1 : the dihedral angle C2-C3···C7-C8 is 30.5 (2)°. Two molecular units of the title compound inter-associate through duplex C9-H···O2 hydrogen bonds to form a cyclic dimer ( Fig. 2 and Table 1). Then, these dimers are stacked via π···π interactions between benzene rings to form ribbon structure extending parallel to b-axis (Fig. 3); the angle between the two planes, centroid-centroid distance and shift distance are 0°, 3.788 Å and 1.613 Å, respectively, as determined by Olex2 program package (Dolomanov et al., 2009). Subsequently, these ribbons are interdigitated to form the final three-dimensional structure (Fig. 4).
The nitro group of the title compound, was found to be a major factor in determining the interactions in the crystal form, unlike in the previously published structures where the pyridinic nitrogen was the main driving force for amolecular association.

Experimental
Crystals of the title compound were obtained by dissolving 1 mmol of 4-(4-nitrobenzyl) pyridine in 30 ml of hot 96% ethanol. Partial evaporation of the hot-filtered solution at room temperature yielded colourless crystals from which a block section was cleaved for the X-ray analysis.

Refinement
The structure was solved by direct methods and refined by least squares method on F2 using the SHELXTL program package. All atoms were refined anisotropically. Hydrogen atoms were placed at the calculated positions using a riding

Figure 1
Molecular unit of the title compound. Thermal ellipsoids are shown at 50% probability.

Figure 2
Structure of the cyclic dimer.

Figure 3
Illustration of the ribbon structure of the title compound.  Illustration of the three dimensional structure of the title compound viewed along the b-axis. 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 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.