Crystal structure of bis(prop-2-yn-1-yl) 5-nitroisophthalate

The whole molecule of the title compound, C14H9NO6, is generated by twofold rotation symmetry; the twofold axis bisects the nitro group and the benzene ring. The nitro group is inclined to the benzene ring by 14.42 (9)°. The prop-2-yn-1-yl groups are inclined to the benzene ring by 13 (2)° and to each other by 24 (3)°; one directed above the plane of the benzene ring and the other below. In the crystal, molecules are linked via pairs of C—H⋯O hydrogen bonds, forming inversion dimers with an R 2 2(18) ring motif. The dimers are linked by further C—H⋯O hydrogen bonds, forming sheets lying parallel to (100).

The whole molecule of the title compound, C 14 H 9 NO 6 , is generated by twofold rotation symmetry; the twofold axis bisects the nitro group and the benzene ring. The nitro group is inclined to the benzene ring by 14.42 (9) . The prop-2-yn-1yl groups are inclined to the benzene ring by 13 (2) and to each other by 24 (3) ; one directed above the plane of the benzene ring and the other below. In the crystal, molecules are linked via pairs of C-HÁ Á ÁO hydrogen bonds, forming inversion dimers with an R 2 2 (18) ring motif. The dimers are linked by further C-HÁ Á ÁO hydrogen bonds, forming sheets lying parallel to (100).

S1. Comments
Carboxylates have promising activity against various antitumor cells (Choudharyl et al., 2002). Nitroaromatic compounds are used in the production of dyes, plastics, high explosives, pharmaceuticals, and pesticides (Somerville et al., 1995). Nitrobenzene is mostly used in the synthesis of aniline and in the production of benzidine, quinolone and azobenzene (Lee et al., 2013).
In the title compound, Fig. 1, the two-fold rotation bisects the benzene ring and the nitro group; atoms C1, C4, H4 and N1 lie on the two-fold rotation axis. The nitro group is inclined to the benzene ring by 14.42 (9) °. The prop-2-yn-1-yl groups are inclined to the benzene ring by 13 (2) ° and to each other by 24 (3) °; one directed above the plane of the benzene ring and the other below.
In the crystal, molecules are linked via pairs of C-H···O hydrogen bonds forming inversion dimers with an R 2 2 (18) ring motif ( Table 1). The dimers are linked by further C-H···O hydrogen bonds forming sheets lying parallel to (100); see Table 1 and Fig. 2.

S2. Synthesis and crystallization
The title compound was synthesized by Steglich esterification of 5-nitro isophthalic acid (1 equiv) which together with propargyl alcohol (2.2 equiv) was added at 273 K to DMAP (2.5 equiv) and DCC (2.2 equiv) in dichloromethane (100 ml). The mixture was stirred under nitrogen at room temperature for 24 h. The white precipitate that formed was filtered off and washed with DCM (150 ml) and brine (150 ml), then dried over Na 2 SO 4 , filtered and evaporated to afforded the title compound. It was purified by column chromatography using CHCl 3 :hexane (9:1) as a eluent. Crystals were obtained by slow evaporation of the solvent.

S3. Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2 The molecular structure of the title compound, with atom labelling. Displacement ellipsoids are drawn at the 30% probability level. The unlabelled atoms are related to the labelled atoms by twofold rotation symmetry [symmetry code: (i) -x + 3/2, -y + 1/2, z].

Figure 2
A view along the a axis of the crystal packing of the title compound. The dashed lines indicate hydrogen bonds (see Table   1 for details). where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 0.26 e Å −3 Δρ min = −0.21 e Å −3 Extinction correction: SHELXL97 (Sheldrick, 2008), Fc * =kFc[1+0.001xFc 2 λ 3 /sin(2θ)] -1/4 Extinction coefficient: 0.030 (5) 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.