4-Nitrophthalonitrile

In the title compound, C8H3N3O2 (systematic name: 4-nitrobenzene-1,2-dicarbonitrile), the nitro group is twisted out of the plane of the benzene ring to which it is attached [O—N—Cring—Cring torsion angle = 9.80 (13)°]. In the crystal packing, supramolecular layers with a zigzag topology in the ac plane are sustained by C—H⋯N interactions.

In the title compound, C 8 H 3 N 3 O 2 (systematic name: 4nitrobenzene-1,2-dicarbonitrile), the nitro group is twisted out of the plane of the benzene ring to which it is attached [O-N-C ring -C ring torsion angle = 9. 80 (13) ]. In the crystal packing, supramolecular layers with a zigzag topology in the ac plane are sustained by C-HÁ Á ÁN interactions.
We gratefully acknowledge funding from the Brunei Research Council, and thank the Ministry of Higher Education (Malaysia) and the University of Malaya for funding structural studies through the High-Impact Research scheme (UM.C/HIR-MOHE/SC/03).
Supporting information for this paper is available from the IUCr electronic archives (Reference: WM5005).

Chemical context
As part of our on-going study of functional phthalocyanines, we have previously reported the synthesis and structure of 4-(prop-2-yn-1-yloxy)benzene-1,2-dicarbonitrile prepared from 4-nitrophthalonitrile (Chin et al., 2012). We now report the structure of the latter.

Structural commentary
In the title compound ( Fig. 1), the nitro group is slightly twisted out of the plane of the benzene ring to which it is attached as seen in the value of the O1-N1-C1-C6 torsion angle of 9.80 (13)°. A similar small twist was found in the structure of the most closely related compound in the literature, i.e. 4-bromo-5-nitrophthalonitrile (Lin et al., 2006).

Refinement
All hydrogen atoms were refined freely.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.