Acta Cryst. (2009). E65, o2446 [ doi:10.1107/S160053680903596X ]
The crystal structure of the title compound, C11H7BrN2O6, establishes the substitution positions of the nitro groups from the nitration reaction of 7-methyl-4-bromomethyl coumarin. The mean planes of the nitro groups form dihedral angles of 43.9 (8) and 52.7 (10)° with the essentially planar [maximum deviation 0.031 (6) Å] benzopyran ring system.
5.06 g of 7-methyl-4-bromomethyl coumarin (0.02 mol) was dissolved in conc. sulfuric acid (10 ml) and treated with a nitrating mixture 15 ml (10 ml H2SO4 + 5 ml HNO3) at ice bath temperatures (273-278K). The reaction mixture was then allowed to stand at room temperature for two hours and the reaction mixture was poured over crushed ice. The separated solid was washed with excess of water, dried and recrystallized from glacial acetic acid. Crystals suitable for diffraction studies were grown by slow evaporation of an ethanol solution of the title compound.
Hydrogen atoms were positioned geometrically with C—H = 0.93-0.97 A° and included in the refinment in a riding-model approximation with Uiso(H) = 1.2 Ueq(C) or 1.5 Ueq(C) for methyl C atoms.
Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SIR92 (Altomare et al., 1994); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).
![[Figure 1]](./lh2864fig1thm.gif)
| Fig. 1. The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atomic numbering. |
| C11H7BrN2O6 | F(000) = 1360 |
| Mr = 343.09 | Dx = 1.825 Mg m−3 |
| Orthorhombic, Pbca | Mo Kα radiation, λ = 0.71069 Å |
| Hall symbol: -P 2ac 2ab | Cell parameters from 25 reflections |
| a = 8.122 (2) Å | θ = 10–15° |
| b = 11.091 (4) Å | µ = 3.32 mm−1 |
| c = 27.723 (6) Å | T = 294 K |
| V = 2497.3 (12) Å3 | Plate, colourless |
| Z = 8 | 0.2 × 0.2 × 0.1 mm |
| Enraf–Nonius CAD-4 diffractometer | 1148 reflections with I > 2σ(I) |
| Radiation source: fine-focus sealed tube | Rint = 0.0000 |
| graphite | θmax = 25.0°, θmin = 2.9° |
| ω–2θ scans | h = 0→9 |
| Absorption correction: ψ scan (North et al., 1968) | k = 0→13 |
| Tmin = 0.520, Tmax = 0.72 | l = 0→32 |
| 2196 measured reflections | 2 standard reflections every 60 min |
| 2196 independent reflections | intensity decay: none |
| Refinement on F2 | 0 restraints |
| Least-squares matrix: full | H-atom parameters constrained |
| R[F2 > 2σ(F2)] = 0.060 | w = 1/[σ2(Fo2) + (0.0687P)2 + 11.8667P] where P = (Fo2 + 2Fc2)/3 |
| wR(F2) = 0.171 | (Δ/σ)max = 0.001 |
| S = 1.05 | Δρmax = 0.63 e Å−3 |
| 2196 reflections | Δρmin = −0.82 e Å−3 |
| 182 parameters |
| C11H7BrN2O6 | V = 2497.3 (12) Å3 |
| Mr = 343.09 | Z = 8 |
| Orthorhombic, Pbca | Mo Kα radiation |
| a = 8.122 (2) Å | µ = 3.32 mm−1 |
| b = 11.091 (4) Å | T = 294 K |
| c = 27.723 (6) Å | 0.2 × 0.2 × 0.1 mm |
| Enraf–Nonius CAD-4 diffractometer | 1148 reflections with I > 2σ(I) |
| Absorption correction: ψ scan (North et al., 1968) | Rint = 0.0000 |
| Tmin = 0.520, Tmax = 0.72 | θmax = 25.0° |
| 2196 measured reflections | 2 standard reflections every 60 min |
| 2196 independent reflections | intensity decay: none |
| R[F2 > 2σ(F2)] = 0.060 | w = 1/[σ2(Fo2) + (0.0687P)2 + 11.8667P] where P = (Fo2 + 2Fc2)/3 |
| wR(F2) = 0.171 | Δρmax = 0.63 e Å−3 |
| S = 1.05 | Δρmin = −0.82 e Å−3 |
| 2196 reflections | Absolute structure: ? |
| 182 parameters | Flack parameter: ? |
| 0 restraints | Rogers parameter: ? |
| H-atom parameters constrained |
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 F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
| x | y | z | Uiso*/Ueq | ||
| C1 | 0.7703 (11) | 0.2886 (7) | 0.6819 (3) | 0.047 (2) | |
| C2 | 0.9438 (10) | 0.2873 (7) | 0.6922 (3) | 0.045 (2) | |
| H3 | 0.9856 | 0.3447 | 0.7134 | 0.054* | |
| C3 | 1.0484 (9) | 0.2073 (6) | 0.6727 (3) | 0.0380 (18) | |
| C4 | 1.0779 (9) | 0.0341 (6) | 0.6146 (3) | 0.0364 (18) | |
| H5 | 1.1898 | 0.0281 | 0.6213 | 0.044* | |
| C5 | 1.0085 (9) | −0.0431 (6) | 0.5812 (2) | 0.0348 (17) | |
| C6 | 0.8400 (9) | −0.0445 (6) | 0.5709 (3) | 0.0395 (19) | |
| C7 | 0.7498 (9) | 0.0406 (6) | 0.5954 (2) | 0.0358 (16) | |
| C8 | 0.9860 (8) | 0.1194 (6) | 0.6381 (3) | 0.0326 (17) | |
| C9 | 0.8194 (9) | 0.1222 (6) | 0.6280 (3) | 0.0339 (17) | |
| C10 | 1.2259 (10) | 0.2058 (7) | 0.6867 (3) | 0.049 (2) | |
| H11A | 1.2542 | 0.2804 | 0.7030 | 0.059* | |
| H11B | 1.2942 | 0.1987 | 0.6581 | 0.059* | |
| C11 | 0.7574 (12) | −0.1318 (7) | 0.5373 (3) | 0.057 (2) | |
| H12A | 0.8385 | −0.1842 | 0.5234 | 0.085* | |
| H12B | 0.7020 | −0.0882 | 0.5122 | 0.085* | |
| H12C | 0.6787 | −0.1790 | 0.5550 | 0.085* | |
| N1 | 1.1229 (9) | −0.1278 (6) | 0.5564 (3) | 0.0483 (17) | |
| N2 | 0.5699 (8) | 0.0459 (6) | 0.5897 (3) | 0.0477 (17) | |
| O1 | 0.7146 (6) | 0.2044 (4) | 0.64815 (18) | 0.0406 (13) | |
| O2 | 0.6689 (8) | 0.3553 (6) | 0.6980 (2) | 0.0649 (18) | |
| O3 | 1.2252 (9) | −0.1757 (6) | 0.5791 (3) | 0.085 (2) | |
| O4 | 1.1032 (9) | −0.1384 (6) | 0.5134 (3) | 0.079 (2) | |
| O5 | 0.5137 (9) | 0.0940 (7) | 0.5564 (3) | 0.099 (3) | |
| O6 | 0.4882 (8) | 0.0020 (9) | 0.6212 (3) | 0.113 (3) | |
| Br | 1.26518 (11) | 0.06847 (7) | 0.72976 (3) | 0.0597 (4) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| C1 | 0.061 (6) | 0.043 (4) | 0.037 (4) | 0.004 (5) | −0.002 (5) | −0.002 (4) |
| C2 | 0.060 (6) | 0.036 (4) | 0.040 (4) | −0.001 (4) | −0.002 (4) | −0.006 (4) |
| C3 | 0.040 (4) | 0.039 (4) | 0.034 (4) | −0.008 (4) | −0.002 (3) | 0.004 (3) |
| C4 | 0.034 (4) | 0.038 (4) | 0.038 (4) | 0.000 (3) | −0.004 (3) | −0.001 (3) |
| C5 | 0.039 (4) | 0.036 (4) | 0.029 (4) | 0.007 (3) | 0.003 (3) | −0.002 (3) |
| C6 | 0.045 (5) | 0.040 (4) | 0.034 (4) | −0.003 (4) | −0.009 (4) | 0.001 (3) |
| C7 | 0.030 (4) | 0.039 (4) | 0.039 (4) | −0.002 (4) | −0.002 (4) | 0.006 (3) |
| C8 | 0.028 (4) | 0.034 (4) | 0.036 (4) | −0.004 (3) | 0.000 (3) | −0.003 (3) |
| C9 | 0.033 (4) | 0.037 (4) | 0.032 (4) | 0.007 (3) | 0.004 (3) | 0.005 (3) |
| C10 | 0.056 (6) | 0.048 (4) | 0.044 (4) | −0.013 (4) | −0.004 (4) | −0.001 (4) |
| C11 | 0.072 (6) | 0.040 (4) | 0.058 (5) | −0.001 (5) | −0.024 (5) | −0.011 (4) |
| N1 | 0.049 (5) | 0.049 (4) | 0.045 (5) | 0.001 (4) | 0.001 (4) | −0.001 (4) |
| N2 | 0.037 (4) | 0.046 (4) | 0.058 (5) | 0.001 (3) | −0.012 (4) | 0.001 (4) |
| O1 | 0.031 (3) | 0.049 (3) | 0.042 (3) | 0.010 (2) | −0.003 (2) | −0.002 (3) |
| O2 | 0.071 (4) | 0.063 (4) | 0.061 (4) | 0.026 (4) | 0.003 (3) | −0.013 (3) |
| O3 | 0.074 (5) | 0.092 (5) | 0.088 (5) | 0.039 (4) | −0.010 (4) | −0.023 (4) |
| O4 | 0.102 (6) | 0.076 (4) | 0.059 (5) | 0.023 (4) | 0.012 (4) | −0.014 (4) |
| O5 | 0.060 (5) | 0.130 (7) | 0.108 (6) | 0.004 (4) | −0.033 (5) | 0.048 (5) |
| O6 | 0.038 (4) | 0.160 (8) | 0.141 (8) | −0.011 (5) | −0.002 (5) | 0.073 (7) |
| Br | 0.0621 (6) | 0.0560 (5) | 0.0611 (6) | 0.0056 (5) | −0.0181 (5) | −0.0042 (4) |
| C1—O2 | 1.194 (9) | C7—C9 | 1.397 (10) |
| C1—O1 | 1.398 (9) | C7—N2 | 1.471 (10) |
| C1—C2 | 1.438 (11) | C8—C9 | 1.382 (9) |
| C2—C3 | 1.342 (10) | C9—O1 | 1.368 (8) |
| C2—H3 | 0.9300 | C10—H11A | 0.9700 |
| C3—C8 | 1.458 (10) | C10—H11B | 0.9700 |
| C3—C10 | 1.494 (11) | C11—H12A | 0.9600 |
| C4—C8 | 1.370 (10) | C11—H12B | 0.9600 |
| C4—C5 | 1.383 (9) | C11—H12C | 0.9600 |
| C4—H5 | 0.9300 | N1—O3 | 1.169 (9) |
| C5—C6 | 1.398 (10) | N1—O4 | 1.210 (9) |
| C5—N1 | 1.488 (10) | N2—O5 | 1.160 (8) |
| C6—C7 | 1.375 (10) | N2—O6 | 1.201 (9) |
| C6—C11 | 1.501 (10) | ||
| O2—C1—O1 | 116.2 (8) | C9—C8—C3 | 117.3 (7) |
| O2—C1—C2 | 127.4 (8) | O1—C9—C8 | 122.8 (7) |
| O1—C1—C2 | 116.3 (7) | O1—C9—C7 | 116.4 (6) |
| C3—C2—C1 | 123.1 (7) | C8—C9—C7 | 120.9 (7) |
| C3—C2—H3 | 118.4 | C3—C10—Br | 108.9 (5) |
| C1—C2—H3 | 118.4 | C3—C10—H11A | 109.9 |
| C2—C3—C8 | 119.2 (7) | Br—C10—H11A | 109.9 |
| C2—C3—C10 | 120.9 (7) | C3—C10—H11B | 109.9 |
| C8—C3—C10 | 120.0 (7) | Br—C10—H11B | 109.9 |
| C8—C4—C5 | 121.6 (7) | H11A—C10—H11B | 108.3 |
| C8—C4—H5 | 119.2 | C6—C11—H12A | 109.5 |
| C5—C4—H5 | 119.2 | C6—C11—H12B | 109.5 |
| C4—C5—C6 | 122.9 (7) | H12A—C11—H12B | 109.5 |
| C4—C5—N1 | 116.5 (7) | C6—C11—H12C | 109.5 |
| C6—C5—N1 | 120.7 (7) | H12A—C11—H12C | 109.5 |
| C7—C6—C5 | 114.4 (7) | H12B—C11—H12C | 109.5 |
| C7—C6—C11 | 120.8 (7) | O3—N1—O4 | 125.5 (8) |
| C5—C6—C11 | 124.8 (7) | O3—N1—C5 | 118.9 (7) |
| C6—C7—C9 | 123.3 (7) | O4—N1—C5 | 115.6 (7) |
| C6—C7—N2 | 120.2 (7) | O5—N2—O6 | 123.2 (8) |
| C9—C7—N2 | 116.5 (6) | O5—N2—C7 | 119.7 (8) |
| C4—C8—C9 | 116.9 (7) | O6—N2—C7 | 117.0 (7) |
| C4—C8—C3 | 125.8 (7) | C9—O1—C1 | 121.2 (6) |
| O2—C1—C2—C3 | 179.1 (8) | C3—C8—C9—O1 | 1.3 (10) |
| O1—C1—C2—C3 | −2.9 (11) | C4—C8—C9—C7 | 0.4 (11) |
| C1—C2—C3—C8 | 2.1 (11) | C3—C8—C9—C7 | −179.7 (6) |
| C1—C2—C3—C10 | −176.6 (7) | C6—C7—C9—O1 | 177.6 (6) |
| C8—C4—C5—C6 | −3.6 (11) | N2—C7—C9—O1 | −4.9 (9) |
| C8—C4—C5—N1 | 177.2 (7) | C6—C7—C9—C8 | −1.5 (11) |
| C4—C5—C6—C7 | 2.5 (11) | N2—C7—C9—C8 | 176.0 (7) |
| N1—C5—C6—C7 | −178.4 (6) | C2—C3—C10—Br | 104.6 (7) |
| C4—C5—C6—C11 | −175.8 (7) | C8—C3—C10—Br | −74.1 (7) |
| N1—C5—C6—C11 | 3.3 (11) | C4—C5—N1—O3 | 41.9 (11) |
| C5—C6—C7—C9 | 0.0 (10) | C6—C5—N1—O3 | −137.3 (8) |
| C11—C6—C7—C9 | 178.4 (7) | C4—C5—N1—O4 | −136.2 (8) |
| C5—C6—C7—N2 | −177.3 (6) | C6—C5—N1—O4 | 44.6 (10) |
| C11—C6—C7—N2 | 1.0 (11) | C6—C7—N2—O5 | −81.1 (10) |
| C5—C4—C8—C9 | 2.0 (11) | C9—C7—N2—O5 | 101.4 (9) |
| C5—C4—C8—C3 | −177.9 (7) | C6—C7—N2—O6 | 101.1 (10) |
| C2—C3—C8—C4 | 178.7 (7) | C9—C7—N2—O6 | −76.4 (10) |
| C10—C3—C8—C4 | −2.6 (11) | C8—C9—O1—C1 | −2.2 (10) |
| C2—C3—C8—C9 | −1.2 (10) | C7—C9—O1—C1 | 178.7 (6) |
| C10—C3—C8—C9 | 177.5 (7) | O2—C1—O1—C9 | −178.9 (7) |
| C4—C8—C9—O1 | −178.6 (6) | C2—C1—O1—C9 | 2.9 (10) |
KVAG gratefully thanks the DST for financial support through the SERC Fast Track Young Scientists Scheme and RG thanks MVJ College of Engineering Bangalore (Reasearch Center). The authors also thanks Professor T. N. Guru Row, Chairman, SSCU IISc, Bangalore, for the X-ray data collection.
Altomare, A., Cascarano, G., Giacovazzo, C., Guagliardi, A., Burla, M. C., Polidori, G. & Camalli, M. (1994). J. Appl. Cryst. 27, 435.
Clayton, A. (1910). J. Chem. Soc. 97, 1397–1408.
Enraf–Nonius (1989). CAD-4 Software. Enraf–Nonius, Delft, The Netherlands.
Farrugia, L. J. (1997). J. Appl. Cryst. 30, 565.
Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.
Kulkarni, M. V., Pujar, B. G. & Patil, V. D. (1983). Arch. Pharm. 316, 15–21.
North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.
Sortur, V., Yenagi, J., Tonannavar, J., Jadhav, V. B. & Kulkarni, M. V. (2006). Spectrochim. Acta A, 64, 301–307.
Vasudevan, K. T., Puttaraja, & Kulkarni, M. V. (1990). Acta Cryst. C46, 2129–2131.
The molecular structure of the title compound is shown in Fig. 1. The bromomethyl group is twisted is out of the plane of the benzopyran ring as described by the torsion angle of 104.6 (7)° for C2-C3-C10-Br. This is in agreement with the ab initio calculations on 6-methyl-4- bromomethylcoumarins (Sortur et al., 2006). Positions C-6 and C-8 (refers to positions from systematic naming scheme) become activated due to the electron donating methyl group at C-7 and hence nitration occurs at C-6 and C-8 consistent with the title compound which is also in agreement with earlier reports (Clayton, 1910; Kulkarni et al., 1983).