Quinoxaline-2-carbonitrile

In the title compound, C9H5N3, the quinoxaline ring is essentially planar, with a maximum deviation of 0.012 (1) Å. Short intermolecular distances between the centroids of the 2,3-dihydropyrazine and benzene rings [3.6490 (5) Å] indicate the existence of π⋯π interactions. In the crystal packing, the molecules are linked via two pairs of intermolecular C—H⋯N interactions, forming R 2 2 (8) and R 2 2 (10) ring motifs; these molecules are further linked into a two-dimensional network parallel to (1 0 2) via another C–H⋯N interaction.


Experimental
A thoroughly ground mixture of selenium dioxide (1.32 g, 12 mmol) and malononitrile (0.26 g, 4 mmol) in 4-5 drops of DMSO was kept stirring in an open-mouth conical flask. The mixture became reddish-brown after 7 min. An exothermic reaction began in the next 10 minutes when triselenium dicyanide was formed. The heterocyclic substrate quinoxaline (0.39 g, 3 mmol) was added to the mixture after the termination of the exothermic reaction. The conical flask was placed in a domestic microwave oven at 240 W for 20 min. The progress of the reaction was monitored by TLC. After completion of the reaction, water was added and the mixture was extracted with chloroform. The organic layer was washed with saturated brine and dried over MgSO 4 and followed by evaporation with a rotary evaporator under low pressure to afford a light yellow substance. This was purified on silica gel (60-120 mesh) column chromatography eluting with petroleum ether (boiling point, 60-80° C) to give the compound (0.34 g, 74 %) as a crystalline solid.

Refinement
All H atoms were located in a difference Fourier map and refined freely.
supplementary materials sup-2 Figures   Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids for non-H atoms and the atom-numbering scheme.   Glazer, 1986) operating at 100.0 (1) 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.