4-Nitro-N-(3-nitrophenyl)benzamide

The title compound, C13H9N3O5, prepared as a solid derivative of 3-nitroanaline via reaction with 4-nitrobenzoyl chloride, crystallizes in a chiral space group. The molecule is non-planar with a dihedral angle of 26.1 (1)° between the two benzene rings. Both nitro groups are twisted slightly out of the plane of their corresponding benzene rings, making dihedral angles of 10.7 (4) and 13.5 (4)°. The molecules are stacked along the a axis with benzene ring centroid–centroid distances of 3.8878 (6) Å. In the crystal, intermolecular benzene C—H⋯O interactions involving one nitro group and the carbonyl group link the molecules, forming chains along [001]. An additional set of aromatic C—H⋯O interactions with the second nitro group form chains along [101], connecting adjacent chains to create layers perpendicular to the b axis.

The title compound, C 13 H 9 N 3 O 5 , prepared as a solid derivative of 3-nitroanaline via reaction with 4-nitrobenzoyl chloride, crystallizes in a chiral space group. The molecule is non-planar with a dihedral angle of 26.1 (1) between the two benzene rings. Both nitro groups are twisted slightly out of the plane of their corresponding benzene rings, making dihedral angles of 10.7 (4) and 13.5 (4) . The molecules are stacked along the a axis with benzene ring centroid-centroid distances of 3.8878 (6) Å . In the crystal, intermolecular benzene C-HÁ Á ÁO interactions involving one nitro group and the carbonyl group link the molecules, forming chains along [001]. An additional set of aromatic C-HÁ Á ÁO interactions with the second nitro group form chains along [101], connecting adjacent chains to create layers perpendicular to the b axis.

Comment
The title compound was prepared as a solid derivative of 3-nitroanaline for a qualitative organic analysis laboratory course.
The starting material was 3-nitroaniline, and reaction with 4-nitrobenzoyl chloride produced a p-nitrobenzamide derivative.
The title compound crystallizes in the chiral spacegroup P2 1 and represents a relatively unusual example of an achiral molecule in a chiral (Sohncke) space group with the conformational flexibility to convert to its mirror image (Pidcock, 2005).
The molecule ( Fig. 1) is non-planar with a dihedral angle of approximately 26.1 (1)° between the two aromatic rings.
In the unit cell, the molecules are stacked along the a axis ( Fig. 2) with aromatic ring centroid-centroid distances of 3.8878 (6) Å, corresponding precisely to the length of the a axis. The ring numbered C1-C6 stacks with a plane-centroid distance of 3.392 (2) Å and a ring shift of 1.899 (4) Å. The ring numbered C8-C13 stacks with a plane-centroid distance of 3.483 (2) Å and a ring shift of 1.728 (4) Å.
The title compound forms hydrogen bonding interactions with adjacent molecules along two different axes to create layers perpendicular to the b axis. The C2-H2···O1 i and C5-H5···O3 ii interactions (Fig. 3, Fig. 4, Table 1) form chains along [001] (all symmetry operators as in Table 1). Additional C13-H13···O5 iii interactions also connect adjacent molecules, with the resulting chains running along [101] (Fig. 5). The position of the N-H in the molecule prevents it from forming a significant hydrogen bonding interaction (H2N···O4 iii distance of 2.65 Å, greater than the sum of the van der Waals radii).

Experimental
Approximately 1.0 g (7.24 mmol) of 3-nitroaniline was dissolved in 3.0 ml of pyridine in a small test tube. To this was added 0.5 g (2.70 mmol) of 4-nitrobenzoyl chloride. This mixture was warmed slightly with a water bath until homogeneous, allowed to cool to room temperature, and then poured into 10.0 ml of water. The solution was allowed to separate and the top layer was decanted. The residue was stirred with 5.0 ml of a 5% Na 2 CO 3 solution, and then cooled in an ice bath to induce crystallization. The crude crystals were filtered, and then recrystallized from absolute ethanol to produce 4-nitro-N-(3-nitrophenyl)benzamide, mp = 502-503 K (lit = 500-501 K, Kang et al. (2008).)

Refinement
All hydrogen atoms were located in difference maps and refined with the atom positions constrained to the external bisector of the appropriate X-C-Y or X-N-Y atom with C-H distances of 0.95 Å and an N-H distance of 0.88 Å. A riding model was used for all H atoms with U iso (H) = 1.2 times U iso (C) or U iso (N). In the absence of significant anomalous scattering effects Friedel pairs were merged in the final refinement.  Fig. 1. The molecular structure of the title compound with the atom labeling scheme drawn with 50% probability displacement ellipsoids for non-H atoms. Fig. 2. The packing of the title compound viewed down the a axis drawn with 50% probability displacement ellipsoids for non-H atoms.    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.