Acta Cryst. (2009). E65, o497 [ doi:10.1107/S1600536809003675 ]
The title compound, C12H8ClN3O3, in the crystalline state and in solution, exists in the azo form, as predicted by density functional theory (DFT) calculations. The molecule is approximately planar [the dihedral angle between the rings is 1.83 (8)°], with the nitro group slightly twisted [13.4 (2)°] relative to the benzene ring. Translationally related molecules form stacks along [010] with an interplanar distance of 3.400 (2) Å. The hydroxy group forms an intramolecular hydrogen bond with the azo N atom.
The title compound was prepared by coupling of p-nitrophenyldiazonium chloride with p-chlorphenol. For details of the synthetic procedure, see Fierz-David & Blangey (1949). Single crystals were grown by slow evaporation of ethanol solution.
H atoms were located in a difference map and refined freely, but at final stage they were positioned geometrically and refined using a riding model with C—H = 0.93 Å, O—H = 0.82 Å and with Uiso(H) = 1.2 times Ueq(C), Uiso(H) = 1.5 times Ueq(O)
Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: PROFIT (Streltsov & Zavodnik, 1989) routine of WinGX (Farrugia, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: PLATON (Spek, 2003).
![[Figure 1]](./gk2186fig1thm.gif)
| Fig. 1. The molecular structure of the title compound with atomic labels and 50% probability displacement ellipsoids for non-H atoms. |
![[Figure 2]](./gk2186fig2thm.gif)
| Fig. 2. Chemical diagrams of (II) and (III). |
| C12H8ClN3O3 | F(000) = 568 |
| Mr = 277.66 | Dx = 1.568 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 25 reflections |
| a = 19.008 (5) Å | θ = 16.8–18.8° |
| b = 4.817 (2) Å | µ = 0.33 mm−1 |
| c = 12.862 (4) Å | T = 291 K |
| β = 92.65 (2)° | Prism, red |
| V = 1176.4 (7) Å3 | 0.40 × 0.20 × 0.15 mm |
| Z = 4 |
| Enraf–Nonius CAD-4 diffractometer | Rint = 0.0 |
| Radiation source: fine-focus sealed tube | θmax = 27.0°, θmin = 1.1° |
| graphite | h = −24→24 |
| nonprofiled ω scans | k = 0→6 |
| 2567 measured reflections | l = 0→16 |
| 2567 independent reflections | 3 standard reflections every 90 min |
| 2110 reflections with I > 2σ(I) | intensity decay: 4% |
| 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)] = 0.037 | Hydrogen site location: inferred from neighbouring sites |
| wR(F2) = 0.098 | H-atom parameters constrained |
| S = 1.56 | w = 1/[σ2(Fo2) + (0.04P)2] where P = (Fo2 + 2Fc2)/3 |
| 2567 reflections | (Δ/σ)max = 0.001 |
| 173 parameters | Δρmax = 0.25 e Å−3 |
| 0 restraints | Δρmin = −0.14 e Å−3 |
| C12H8ClN3O3 | V = 1176.4 (7) Å3 |
| Mr = 277.66 | Z = 4 |
| Monoclinic, P21/c | Mo Kα radiation |
| a = 19.008 (5) Å | µ = 0.33 mm−1 |
| b = 4.817 (2) Å | T = 291 K |
| c = 12.862 (4) Å | 0.40 × 0.20 × 0.15 mm |
| β = 92.65 (2)° |
| Enraf–Nonius CAD-4 diffractometer | Rint = 0.0 |
| 2567 measured reflections | θmax = 27.0° |
| 2567 independent reflections | 3 standard reflections every 90 min |
| 2110 reflections with I > 2σ(I) | intensity decay: 4% |
| R[F2 > 2σ(F2)] = 0.037 | H-atom parameters constrained |
| wR(F2) = 0.098 | Δρmax = 0.25 e Å−3 |
| S = 1.56 | Δρmin = −0.14 e Å−3 |
| 2567 reflections | Absolute structure: ? |
| 173 parameters | Flack parameter: ? |
| 0 restraints | Rogers parameter: ? |
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 | ||
| Cl1 | 0.463076 (19) | 1.28010 (9) | 0.16237 (3) | 0.06275 (16) | |
| O1 | 0.27449 (6) | 0.7166 (3) | −0.14202 (8) | 0.0703 (4) | |
| H1 | 0.2491 | 0.6045 | −0.1138 | 0.105* | |
| O2 | −0.00077 (6) | −0.4250 (3) | 0.11633 (9) | 0.0665 (3) | |
| O3 | 0.05796 (6) | −0.4261 (2) | 0.26393 (8) | 0.0592 (3) | |
| N1 | 0.27334 (5) | 0.5696 (2) | 0.07974 (9) | 0.0436 (3) | |
| N2 | 0.23136 (6) | 0.4462 (2) | 0.01583 (9) | 0.0450 (3) | |
| N3 | 0.04760 (6) | −0.3453 (2) | 0.17452 (10) | 0.0468 (3) | |
| C1 | 0.31710 (7) | 0.8384 (3) | −0.07021 (11) | 0.0496 (4) | |
| C2 | 0.31686 (6) | 0.7693 (3) | 0.03656 (10) | 0.0420 (3) | |
| C3 | 0.36225 (7) | 0.9076 (3) | 0.10740 (11) | 0.0444 (3) | |
| H3 | 0.3620 | 0.8642 | 0.1778 | 0.053* | |
| C4 | 0.40705 (7) | 1.1065 (3) | 0.07365 (12) | 0.0475 (3) | |
| C5 | 0.40778 (8) | 1.1751 (3) | −0.03104 (12) | 0.0556 (4) | |
| H5 | 0.4387 | 1.3097 | −0.0534 | 0.067* | |
| C6 | 0.36281 (8) | 1.0440 (4) | −0.10150 (12) | 0.0589 (4) | |
| H6 | 0.3629 | 1.0935 | −0.1714 | 0.071* | |
| C11 | 0.18678 (6) | 0.2481 (3) | 0.06134 (10) | 0.0402 (3) | |
| C12 | 0.18713 (7) | 0.1938 (3) | 0.16816 (11) | 0.0472 (3) | |
| H12 | 0.2177 | 0.2884 | 0.2143 | 0.057* | |
| C13 | 0.14144 (7) | −0.0020 (3) | 0.20368 (10) | 0.0473 (3) | |
| H13 | 0.1412 | −0.0428 | 0.2743 | 0.057* | |
| C14 | 0.09613 (6) | −0.1372 (3) | 0.13447 (10) | 0.0401 (3) | |
| C15 | 0.09456 (7) | −0.0863 (3) | 0.02927 (10) | 0.0456 (3) | |
| H15 | 0.0634 | −0.1801 | −0.0161 | 0.055* | |
| C16 | 0.14084 (7) | 0.1087 (3) | −0.00691 (11) | 0.0469 (3) | |
| H16 | 0.1411 | 0.1465 | −0.0778 | 0.056* |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| Cl1 | 0.0544 (2) | 0.0552 (3) | 0.0784 (3) | −0.00993 (18) | 0.00095 (19) | −0.0052 (2) |
| O1 | 0.0844 (8) | 0.0812 (9) | 0.0452 (6) | −0.0262 (7) | 0.0024 (5) | 0.0036 (6) |
| O2 | 0.0716 (7) | 0.0648 (8) | 0.0636 (7) | −0.0297 (6) | 0.0068 (6) | −0.0067 (6) |
| O3 | 0.0716 (7) | 0.0500 (6) | 0.0570 (7) | −0.0031 (5) | 0.0129 (5) | 0.0118 (5) |
| N1 | 0.0437 (6) | 0.0373 (6) | 0.0502 (6) | 0.0005 (5) | 0.0071 (5) | 0.0018 (5) |
| N2 | 0.0460 (6) | 0.0406 (6) | 0.0486 (6) | −0.0002 (5) | 0.0054 (5) | 0.0021 (5) |
| N3 | 0.0548 (7) | 0.0348 (6) | 0.0518 (7) | 0.0001 (5) | 0.0128 (5) | −0.0031 (5) |
| C1 | 0.0523 (8) | 0.0494 (8) | 0.0477 (8) | 0.0001 (7) | 0.0095 (6) | 0.0004 (7) |
| C2 | 0.0418 (6) | 0.0367 (7) | 0.0482 (8) | 0.0030 (6) | 0.0092 (6) | 0.0027 (6) |
| C3 | 0.0452 (7) | 0.0382 (7) | 0.0502 (7) | 0.0040 (6) | 0.0072 (6) | 0.0035 (6) |
| C4 | 0.0432 (7) | 0.0373 (7) | 0.0626 (9) | 0.0023 (6) | 0.0067 (6) | −0.0042 (7) |
| C5 | 0.0551 (8) | 0.0473 (9) | 0.0663 (10) | −0.0056 (7) | 0.0214 (7) | 0.0042 (8) |
| C6 | 0.0663 (9) | 0.0596 (10) | 0.0522 (9) | −0.0060 (8) | 0.0176 (7) | 0.0075 (8) |
| C11 | 0.0402 (6) | 0.0351 (7) | 0.0456 (7) | 0.0033 (5) | 0.0055 (5) | 0.0018 (6) |
| C12 | 0.0478 (7) | 0.0485 (8) | 0.0451 (8) | −0.0054 (6) | 0.0000 (6) | −0.0017 (6) |
| C13 | 0.0537 (8) | 0.0501 (8) | 0.0384 (7) | −0.0021 (7) | 0.0041 (6) | 0.0024 (6) |
| C14 | 0.0419 (6) | 0.0296 (6) | 0.0492 (7) | 0.0025 (5) | 0.0081 (5) | −0.0005 (6) |
| C15 | 0.0505 (7) | 0.0426 (8) | 0.0432 (7) | −0.0058 (6) | −0.0015 (6) | −0.0025 (6) |
| C16 | 0.0540 (8) | 0.0472 (8) | 0.0395 (7) | −0.0023 (6) | 0.0030 (6) | 0.0053 (6) |
| Cl1—C4 | 1.7387 (16) | C4—C5 | 1.387 (2) |
| O1—C1 | 1.3358 (17) | C5—C6 | 1.371 (2) |
| O1—H1 | 0.8200 | C5—H5 | 0.9300 |
| O2—N3 | 1.2203 (15) | C6—H6 | 0.9300 |
| O3—N3 | 1.2214 (15) | C11—C16 | 1.3831 (18) |
| N1—N2 | 1.2670 (16) | C11—C12 | 1.3983 (19) |
| N1—C2 | 1.4001 (17) | C12—C13 | 1.3743 (19) |
| N2—C11 | 1.4203 (17) | C12—H12 | 0.9300 |
| N3—C14 | 1.4712 (17) | C13—C14 | 1.3741 (19) |
| C1—C6 | 1.389 (2) | C13—H13 | 0.9300 |
| C1—C2 | 1.413 (2) | C14—C15 | 1.3741 (19) |
| C2—C3 | 1.3949 (19) | C15—C16 | 1.3823 (19) |
| C3—C4 | 1.3660 (19) | C15—H15 | 0.9300 |
| C3—H3 | 0.9300 | C16—H16 | 0.9300 |
| C1—O1—H1 | 109.5 | C5—C6—C1 | 121.06 (14) |
| N2—N1—C2 | 115.52 (11) | C5—C6—H6 | 119.5 |
| N1—N2—C11 | 114.69 (11) | C1—C6—H6 | 119.5 |
| O2—N3—O3 | 124.14 (12) | C16—C11—C12 | 120.47 (12) |
| O2—N3—C14 | 117.79 (12) | C16—C11—N2 | 115.84 (12) |
| O3—N3—C14 | 118.06 (12) | C12—C11—N2 | 123.69 (12) |
| O1—C1—C6 | 118.70 (13) | C13—C12—C11 | 118.72 (13) |
| O1—C1—C2 | 122.63 (13) | C13—C12—H12 | 120.6 |
| C6—C1—C2 | 118.67 (14) | C11—C12—H12 | 120.6 |
| C3—C2—N1 | 115.33 (12) | C14—C13—C12 | 119.79 (12) |
| C3—C2—C1 | 119.50 (13) | C14—C13—H13 | 120.1 |
| N1—C2—C1 | 125.17 (13) | C12—C13—H13 | 120.1 |
| C4—C3—C2 | 120.21 (13) | C13—C14—C15 | 122.53 (12) |
| C4—C3—H3 | 119.9 | C13—C14—N3 | 118.73 (12) |
| C2—C3—H3 | 119.9 | C15—C14—N3 | 118.75 (12) |
| C3—C4—C5 | 120.66 (14) | C14—C15—C16 | 117.88 (12) |
| C3—C4—Cl1 | 120.05 (12) | C14—C15—H15 | 121.1 |
| C5—C4—Cl1 | 119.29 (11) | C16—C15—H15 | 121.1 |
| C6—C5—C4 | 119.88 (14) | C15—C16—C11 | 120.61 (12) |
| C6—C5—H5 | 120.1 | C15—C16—H16 | 119.7 |
| C4—C5—H5 | 120.1 | C11—C16—H16 | 119.7 |
| C2—N1—N2—C11 | −178.90 (10) | N1—N2—C11—C16 | −179.47 (11) |
| N2—N1—C2—C3 | 179.08 (11) | N1—N2—C11—C12 | 1.27 (18) |
| N2—N1—C2—C1 | −0.30 (19) | C16—C11—C12—C13 | 0.5 (2) |
| O1—C1—C2—C3 | −179.22 (13) | N2—C11—C12—C13 | 179.77 (12) |
| C6—C1—C2—C3 | −0.1 (2) | C11—C12—C13—C14 | −0.7 (2) |
| O1—C1—C2—N1 | 0.1 (2) | C12—C13—C14—C15 | 0.4 (2) |
| C6—C1—C2—N1 | 179.24 (13) | C12—C13—C14—N3 | −179.82 (12) |
| N1—C2—C3—C4 | 179.97 (11) | O2—N3—C14—C13 | 166.51 (12) |
| C1—C2—C3—C4 | −0.6 (2) | O3—N3—C14—C13 | −13.07 (17) |
| C2—C3—C4—C5 | 0.4 (2) | O2—N3—C14—C15 | −13.72 (18) |
| C2—C3—C4—Cl1 | 179.53 (10) | O3—N3—C14—C15 | 166.71 (12) |
| C3—C4—C5—C6 | 0.5 (2) | C13—C14—C15—C16 | 0.1 (2) |
| Cl1—C4—C5—C6 | −178.60 (12) | N3—C14—C15—C16 | −179.63 (11) |
| C4—C5—C6—C1 | −1.3 (2) | C14—C15—C16—C11 | −0.3 (2) |
| O1—C1—C6—C5 | −179.81 (14) | C12—C11—C16—C15 | 0.0 (2) |
| C2—C1—C6—C5 | 1.1 (2) | N2—C11—C16—C15 | −179.28 (12) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O1—H1···N2 | 0.82 | 1.88 | 2.5777 (17) | 143 |
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The present work was fulfilled in the course of study of the hydroxyazo-ketohydrazone tautomerism in phenylazophenols. The title compound, (I), exists in crystals as the azo form (Fig. 1). It is evidenced, firstly, by the fact that the H atom was found and refined in the vicinity of O atom, and secondly, by comparison of the molecular geometry with numerous structures of azo tautomers found in the Cambridge Structural Database (Allen, 2002). Since the UV–visible spectra of the crystalline title compound resemble its spectra in solutions, the azo tautomer has to predominate in solutions as well.
However, recently it has been reported that (1Z)-4-hydroxybenzo-1,2-quinone 1-[(2-chloro-4-nitrophenyl)hydrazone (II), the compound closely related to (I), exists in crystals as the hydrazone tautomer (You et al., 2004).
The azo–hydrazone equilibrium is known to be shifted by the effect of donor and acceptor substituents and also by intra- and intermolecular hydrogen bonds. In order to evaluate the relative importance of these factors, we have performed the DFT calculations of azo and hydrazone tautomers of (I) and (II). Calculations were carried out using GAMESS (Schmidt et al., 1993) with B3LYP exchange-correlation functional (Becke, 1993; Lee et al., 1988) and 6-311G** basis set (Krishnan et al., 1980). After geometry of an isolated molecule has been optimized, molecular structure was fixed, and the effect of nonspecific intermolecular interactions was accounted by COSMO method (Klamt & Schüürmann, 1993), taking the dielectric permeability equal to 10. The results indicate that for 2-phenyldiazenylphenol (III), the azo form is by 10.5 kJ/mol more stable than the hydrazone form. For compound (I), this difference decreases to 7.5 kJ/mol and for (II) - to 6.8 kJ/mol, but nonetheless the azo form is still preferable.
Thus, the difference between (I) and (II) most probably arises from specific intermolecular interactions. In (I), there is the only worthnoting intermolecular contact C15—H15···O2 (-x, -1 - y, -z) (H15···O2 2.56 Å, C15···O2 3.452 (2) Å, C15—H15···O2 161°), which cannot have any effect on the relative stability of tautomers. In (II), the keto group forms a strong hydrogen bond with the hydroxy group of a neighboring molecule (O···H 1.74 Å, O···O 2.581 (2) Å, O—H···O 173°). This interaction stabilizes the hydrazone tautomer, according to the conception of resonance-assisted hydrogen bonds (Gilli et al., 1989). So, the shift of tautomeric equilibrium in (II) towards the hydrazone form should be most probably rationalized by formation of intermolecular hydrogen bonds.