Acta Cryst. (2009). E65, o954 [ doi:10.1107/S1600536809011830 ]
The crystal structure of the title compound, C7H5NO4, was first reported by Kurahashi, Fukuyo & Shimada [(1967). Bull. Chem. Soc. Jpn, 40, 1296]. It has been re-examined, improving the precision of the derived geometric parameters. The asymmetric unit comprises a non-planar independent molecule, as the nitro and the carboxy substituents force each other to be twisted away from the plane of the aromatic ring by 54.9 (2) and 24.0 (2)°, respectively. The molecules form a conventional dimeric unit via centrosymmetric intermolecular hydrogen bonds.
o-Nitrobenzoic acid (0.1 mmol, Sigma Aldrich at 95% purity) was dissolved in water (5 ml) and gently heated under reflux for 1 h. After cooling the solution to an ambient temperature, crystals suitable for single-crystal X-ray diffraction were grown by slow evaporation of the solvent after few days.
All H atoms were found in a difference map and then treated as riding atoms, with C—H = 0.93Å and Uiso values equal to 1.2Ueq(C, phenyl). The remaining H atom of the carboxy group was freely refined.
Data collection: CrysAlis CCD (Oxford Diffraction, 2006); cell refinement: CrysAlis RED (Oxford Diffraction, 2006); data reduction: CrysAlis RED (Oxford Diffraction, 2006); program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
![[Figure 1]](./kp2213fig1thm.gif)
| Fig. 1. The molecular structure of (I), showing the atom-labelling scheme. Displacements ellipsoids are at the 50% probability level. |
![[Figure 2]](./kp2213fig2thm.gif)
| Fig. 2. Crystal packing diagram for (I) viewed approximately down a. All atoms are shown as small spheres of arbitrary radii. For the sake of clarity, H atoms not involved in hydrogen bonding have been omitted. Hydrogen bonding is indicated by dashed lines. |
| C7H5NO4 | Z = 2 |
| Mr = 167.12 | F(000) = 172 |
| Triclinic, P1 | Dx = 1.566 Mg m−3 |
| Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
| a = 5.0147 (15) Å | Cell parameters from 861 reflections |
| b = 7.527 (2) Å | θ = 3.0–32.5° |
| c = 10.620 (2) Å | µ = 0.13 mm−1 |
| α = 69.41 (2)° | T = 298 K |
| β = 86.07 (2)° | Tablets, colourless |
| γ = 71.01 (3)° | 0.15 × 0.15 × 0.10 mm |
| V = 354.35 (18) Å3 |
| Oxford Diffraction Xcalibur S CCD diffractometer | 1872 independent reflections |
| Radiation source: Enhance (Mo) X-ray Source | 1087 reflections with I > 2σ(I) |
| graphite | Rint = 0.050 |
| Detector resolution: 16.0696 pixels mm-1 | θmax = 29.0°, θmin = 3.0° |
| ω and φ scans | h = −6→6 |
| Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006) | k = −10→10 |
| Tmin = 0.879, Tmax = 0.980 | l = −14→14 |
| 3862 measured reflections |
| Refinement on F2 | Primary atom site location: structure-invariant direct methods |
| Least-squares matrix: full | Secondary atom site location: difference Fourier map |
| R[F2 > 2σ(F2)] = 0.077 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.148 | H atoms treated by a mixture of independent and constrained refinement |
| S = 1.07 | w = 1/[σ2(Fo2) + (0.0536P)2 + 0.0451P] where P = (Fo2 + 2Fc2)/3 |
| 1872 reflections | (Δ/σ)max < 0.001 |
| 113 parameters | Δρmax = 0.26 e Å−3 |
| 0 restraints | Δρmin = −0.20 e Å−3 |
| C7H5NO4 | γ = 71.01 (3)° |
| Mr = 167.12 | V = 354.35 (18) Å3 |
| Triclinic, P1 | Z = 2 |
| a = 5.0147 (15) Å | Mo Kα radiation |
| b = 7.527 (2) Å | µ = 0.13 mm−1 |
| c = 10.620 (2) Å | T = 298 K |
| α = 69.41 (2)° | 0.15 × 0.15 × 0.10 mm |
| β = 86.07 (2)° |
| Oxford Diffraction Xcalibur S CCD diffractometer | 1872 independent reflections |
| Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction, 2006) | 1087 reflections with I > 2σ(I) |
| Tmin = 0.879, Tmax = 0.980 | Rint = 0.050 |
| 3862 measured reflections | θmax = 29.0° |
| R[F2 > 2σ(F2)] = 0.077 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.148 | Δρmax = 0.26 e Å−3 |
| S = 1.07 | Δρmin = −0.20 e Å−3 |
| 1872 reflections | Absolute structure: ? |
| 113 parameters | Flack parameter: ? |
| 0 restraints | Rogers parameter: ? |
Experimental. Absorption correction: CrysAlis RED, Oxford Diffraction Ltd., Version 1.171.32.29 (release 10-06-2008 CrysAlis171 .NET) (compiled Jun 10 2008,16:49:55) Empirical absorption correction using spherical harmonics, implemented in SCALE3 ABSPACK scaling algorithm. |
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 | ||
| O1 | 0.8083 (4) | 0.3762 (3) | 0.6058 (2) | 0.0471 (6) | |
| O2 | 1.2483 (4) | 0.2482 (3) | 0.5512 (2) | 0.0481 (6) | |
| H2 | 1.221 (7) | 0.378 (5) | 0.504 (3) | 0.068 (11)* | |
| O3 | 0.7790 (4) | 0.2147 (3) | 0.8921 (2) | 0.0537 (6) | |
| O4 | 0.4118 (4) | 0.1514 (3) | 0.8517 (2) | 0.0533 (6) | |
| N1 | 0.6642 (5) | 0.1288 (3) | 0.8481 (2) | 0.0344 (5) | |
| C1 | 1.0287 (5) | 0.0235 (3) | 0.6923 (2) | 0.0305 (6) | |
| C2 | 0.8416 (5) | −0.0231 (4) | 0.7933 (2) | 0.0297 (6) | |
| C3 | 0.8224 (6) | −0.2123 (4) | 0.8508 (3) | 0.0381 (7) | |
| H3 | 0.6904 | −0.2375 | 0.9147 | 0.046* | |
| C4 | 1.0025 (6) | −0.3648 (4) | 0.8123 (3) | 0.0450 (7) | |
| H4 | 0.9927 | −0.4941 | 0.8503 | 0.054* | |
| C5 | 1.1971 (6) | −0.3249 (4) | 0.7172 (3) | 0.0440 (8) | |
| H5 | 1.3219 | −0.4286 | 0.6933 | 0.053* | |
| C6 | 1.2084 (6) | −0.1327 (4) | 0.6572 (3) | 0.0393 (7) | |
| H6 | 1.3386 | −0.1080 | 0.5922 | 0.047* | |
| C7 | 1.0188 (5) | 0.2327 (4) | 0.6144 (3) | 0.0334 (6) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| O1 | 0.0457 (12) | 0.0296 (10) | 0.0542 (13) | −0.0083 (9) | 0.0228 (10) | −0.0080 (9) |
| O2 | 0.0461 (13) | 0.0350 (12) | 0.0543 (13) | −0.0151 (9) | 0.0236 (10) | −0.0071 (10) |
| O3 | 0.0600 (14) | 0.0563 (13) | 0.0657 (14) | −0.0290 (11) | 0.0177 (11) | −0.0391 (12) |
| O4 | 0.0361 (12) | 0.0638 (14) | 0.0638 (15) | −0.0131 (10) | 0.0160 (10) | −0.0321 (12) |
| N1 | 0.0411 (14) | 0.0319 (12) | 0.0275 (12) | −0.0140 (10) | 0.0117 (10) | −0.0071 (10) |
| C1 | 0.0335 (14) | 0.0287 (14) | 0.0275 (13) | −0.0088 (11) | 0.0023 (11) | −0.0090 (11) |
| C2 | 0.0312 (13) | 0.0300 (14) | 0.0270 (13) | −0.0084 (10) | 0.0045 (11) | −0.0106 (11) |
| C3 | 0.0486 (17) | 0.0355 (15) | 0.0323 (15) | −0.0205 (12) | 0.0114 (13) | −0.0097 (12) |
| C4 | 0.062 (2) | 0.0263 (14) | 0.0437 (17) | −0.0150 (13) | 0.0056 (15) | −0.0079 (13) |
| C5 | 0.0530 (18) | 0.0312 (15) | 0.0436 (17) | −0.0052 (12) | 0.0085 (14) | −0.0169 (13) |
| C6 | 0.0402 (16) | 0.0393 (16) | 0.0357 (15) | −0.0105 (12) | 0.0132 (13) | −0.0138 (13) |
| C7 | 0.0392 (15) | 0.0320 (14) | 0.0304 (14) | −0.0148 (12) | 0.0131 (12) | −0.0116 (11) |
| O1—C7 | 1.222 (3) | C2—C3 | 1.372 (3) |
| O2—C7 | 1.310 (3) | C3—C4 | 1.380 (3) |
| O2—H2 | 0.90 (3) | C3—H3 | 0.9300 |
| O3—N1 | 1.208 (3) | C4—C5 | 1.381 (4) |
| O4—N1 | 1.221 (3) | C4—H4 | 0.9300 |
| N1—C2 | 1.474 (3) | C5—C6 | 1.379 (4) |
| C1—C6 | 1.381 (3) | C5—H5 | 0.9300 |
| C1—C2 | 1.402 (3) | C6—H6 | 0.9300 |
| C1—C7 | 1.485 (3) | ||
| C7—O2—H2 | 108 (2) | C3—C4—C5 | 119.8 (2) |
| O3—N1—O4 | 124.6 (2) | C3—C4—H4 | 120.1 |
| O3—N1—C2 | 118.2 (2) | C5—C4—H4 | 120.1 |
| O4—N1—C2 | 117.1 (2) | C6—C5—C4 | 120.6 (2) |
| C6—C1—C2 | 117.2 (2) | C6—C5—H5 | 119.7 |
| C6—C1—C7 | 119.9 (2) | C4—C5—H5 | 119.7 |
| C2—C1—C7 | 122.7 (2) | C5—C6—C1 | 120.9 (2) |
| C3—C2—C1 | 122.5 (2) | C5—C6—H6 | 119.6 |
| C3—C2—N1 | 116.4 (2) | C1—C6—H6 | 119.6 |
| C1—C2—N1 | 121.1 (2) | O1—C7—O2 | 123.4 (2) |
| C2—C3—C4 | 118.9 (2) | O1—C7—C1 | 122.2 (2) |
| C2—C3—H3 | 120.6 | O2—C7—C1 | 114.4 (2) |
| C4—C3—H3 | 120.6 | ||
| C6—C1—C2—C3 | −3.7 (4) | C2—C3—C4—C5 | −0.1 (4) |
| C7—C1—C2—C3 | 169.9 (3) | C3—C4—C5—C6 | −1.9 (4) |
| C6—C1—C2—N1 | 173.2 (2) | C4—C5—C6—C1 | 1.1 (4) |
| C7—C1—C2—N1 | −13.3 (4) | C2—C1—C6—C5 | 1.6 (4) |
| O3—N1—C2—C3 | 122.6 (3) | C7—C1—C6—C5 | −172.1 (3) |
| O4—N1—C2—C3 | −53.9 (3) | C6—C1—C7—O1 | 152.9 (3) |
| O3—N1—C2—C1 | −54.5 (3) | C2—C1—C7—O1 | −20.5 (4) |
| O4—N1—C2—C1 | 129.1 (3) | C6—C1—C7—O2 | −23.9 (4) |
| C1—C2—C3—C4 | 2.9 (4) | C2—C1—C7—O2 | 162.7 (2) |
| N1—C2—C3—C4 | −174.1 (2) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O2—H2···O1i | 0.90 (3) | 1.77 (4) | 2.660 (3) | 173 (3) |
| Symmetry codes: (i) −x+2, −y+1, −z+1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O2—H2···O1i | 0.90 (3) | 1.77 (4) | 2.660 (3) | 173 (3) |
| Symmetry codes: (i) −x+2, −y+1, −z+1. |
We thank MIUR (Rome) for 2006 financial support of the project 'X-ray diffractometry and spectrometry'.
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o-Nitrobenzoic acid was determined more than 40 years ago (Kurahashi et al., 1967), but the final refinement was carried only to R=0.18. Subsequently, a new X-ray structure determination was reported (Sakore et al., 1967). In this study, 1250 unique reflections were collected at ambient temperature on an equi-inclination Weissenberg camera using Cu Kα radiation. Data were corrected for Lp effects as well as for the effect of spot extension, but not for absorption [µ(Cu Kα)= 135 mm-1]. 694 visually estimated reflections having values significantly above background were used in the isotropic least-squares refinement. The final calculations led to R = 0.142 for 49 refined parameters, as the H atoms were not localized. A further anisotropic refinement of the structure was eventually carried out (Tavale & Pant, 1973). In this calculation, based on the same data set but with the inclusion of H atoms. the R factor decreased to 0.104, with a data-to-parameter ratio of 5.6, and average standard deviations of 0.013Å in C—C bond lengths and 0.9° in bond angles.
The asymmetric unit of (I) comprises a non-planar independent molecule, as the nitro and carboxy substituents force each other to be twisted away from the plane of the aromatic ring by 54.9 (2) and 24.0 (2)°, respectively (Fig. 1). The pattern of bond lengths and bond angles is consistent with those reported in previous structural investigations concerning the effect of the nitro and the carboxy groups on the geometry of polysubstituted benzene rings (Colapietro et al., 1984; Domenicano et al., 1989). Analysis of the crystal packing of (I), (Fig. 2), shows that the molecular components form the conventional dimeric units observed in monocarboylic acids (Leiserowitz, 1976). The structure is stabilized by very short [2.660 (3) Å] intermolecular O—H···O interactions of descriptor R22(8) (Etter et al., 1990; Bernstein et al., 1995; Motherwell et al., 1999) (Table 1) between the OH moiety and the carbonyl O atom (O1i) [symmetry code: (i) -x + 2, -y + 1, -z + 1].