Acta Cryst. (2009). E65, o1218 [ doi:10.1107/S1600536809016456 ]
In the crystal of the title molecular salt (systematic name: 2-acetylpyridinium 2,5-dibromo-4-hydroxy-3,6-dioxocyclohexa-1,4-dienolate), C7H8NO+·C6HBr2O4-, centrosymmetric rings consisting of two cations and two anions are formed, with the components linked by alternating O-H
O and N-HO hydrogen bonds. Short OBr contacts [3.243 (2) and 3.359 (2) Å] may help to consolidate the packing.
Red blocks of (I) were grown by slow evaporation of solvent from a 1:1 solution of bromanilic acid and 2-acetylpyridine in methanol.
The H atoms were identified in the difference map, and their positions were freely refined. The O- and N-bonded species were allowed to refine isotropically and the C-bonded H atoms were constrained, with Uiso(H) = 1.2Ueq(C).
Data collection: CrystalClear (Rigaku/MSC, 2008); cell refinement: CrystalClear (Rigaku/MSC, 2008); data reduction: CrystalClear (Rigaku/MSC, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and Mercury (Macrae et al., 2006); software used to prepare material for publication: WinGX (Farrugia, 1999).
![[Figure 1]](./hb2948fig1thm.gif)
| Fig. 1. The molecular structure of (I) with displacement ellipsoids drawn at the 50% probability level. |
![[Figure 2]](./hb2948fig2thm.gif)
| Fig. 2. The hydrogen bonded ring between alternating bromanilic acid and acetylpyridine molecules. The hydrogen bonds are indicated by dashed lines. The * indicates the atoms are related by the symmetry code 2 - x, 1 - y, 1 - z. |
![[Figure 3]](./hb2948fig3thm.gif)
| Fig. 3. The short bromine-oxygen close contacts connecting the hydrogen bonded rings. The short contacts and hydrogen bonds are indicated by dashed lines. |
| C7H8NO+·C6HBr2O4– | F000 = 816 |
| Mr = 419.03 | Dx = 2.014 Mg m−3 |
| Monoclinic, P21/c | Mo Kα radiation λ = 0.71073 Å |
| Hall symbol: -P 2ybc | Cell parameters from 13698 reflections |
| a = 9.1323 (5) Å | θ = 6.1–55.2º |
| b = 13.3821 (7) Å | µ = 5.89 mm−1 |
| c = 12.2287 (7) Å | T = 100 K |
| β = 112.396 (2)º | Block, red |
| V = 1381.74 (13) Å3 | 0.25 × 0.2 × 0.1 mm |
| Z = 4 |
| Rigaku R-AXIS RAPID IP diffractometer | 2793 reflections with I > 2σ(I) |
| Monochromator: graphite | Rint = 0.036 |
| T = 100 K | θmax = 27.5º |
| ω scans | θmin = 3.0º |
| Absorption correction: empirical (using intensity measurements) (CrystalClear; Rigaku/MSC, 2008) | h = −11→11 |
| Tmin = 0.561, Tmax = 1.000 | k = −17→17 |
| 17193 measured reflections | l = −15→15 |
| 3156 independent reflections |
| Refinement on F2 | Secondary atom site location: difference Fourier map |
| Least-squares matrix: full | Hydrogen site location: difference Fourier map |
| R[F2 > 2σ(F2)] = 0.022 | H atoms treated by a mixture of independent and constrained refinement |
| wR(F2) = 0.050 | w = 1/[σ2(Fo2) + (0.0229P)2 + 0.7894P] where P = (Fo2 + 2Fc2)/3 |
| S = 1.04 | (Δ/σ)max = 0.001 |
| 3156 reflections | Δρmax = 0.43 e Å−3 |
| 219 parameters | Δρmin = −0.31 e Å−3 |
| Primary atom site location: structure-invariant direct methods | Extinction correction: none |
| C7H8NO+·C6HBr2O4– | V = 1381.74 (13) Å3 |
| Mr = 419.03 | Z = 4 |
| Monoclinic, P21/c | Mo Kα |
| a = 9.1323 (5) Å | µ = 5.89 mm−1 |
| b = 13.3821 (7) Å | T = 100 K |
| c = 12.2287 (7) Å | 0.25 × 0.2 × 0.1 mm |
| β = 112.396 (2)º |
| Rigaku R-AXIS RAPID IP diffractometer | 3156 independent reflections |
| Absorption correction: empirical (using intensity measurements) (CrystalClear; Rigaku/MSC, 2008) | 2793 reflections with I > 2σ(I) |
| Tmin = 0.561, Tmax = 1.000 | Rint = 0.036 |
| 17193 measured reflections |
| R[F2 > 2σ(F2)] = 0.022 | 219 parameters |
| wR(F2) = 0.050 | H atoms treated by a mixture of independent and constrained refinement |
| S = 1.04 | Δρmax = 0.43 e Å−3 |
| 3156 reflections | Δρmin = −0.31 e Å−3 |
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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 > 2σ(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. The isotropic displacement parameters for the hydrogen atoms involved in hydrogenbonds are refined freely. All other hydrogen atoms are refined against the atoms to which they are bonded. |
| x | y | z | Uiso*/Ueq | ||
| H6 | 0.611 (3) | 0.307 (2) | 0.195 (3) | 0.041 (8)* | |
| O5 | 0.50649 (17) | 0.44777 (11) | 0.25644 (13) | 0.0201 (3) | |
| N1 | 0.5396 (2) | 0.29814 (12) | 0.11977 (16) | 0.0152 (3) | |
| C12 | 0.4282 (2) | 0.45501 (15) | 0.15172 (18) | 0.0160 (4) | |
| C11 | 0.5549 (2) | 0.22016 (16) | 0.05849 (19) | 0.0200 (4) | |
| H5 | 0.637 (3) | 0.1735 (18) | 0.102 (2) | 0.024* | |
| C8 | 0.3294 (2) | 0.36207 (16) | −0.04572 (18) | 0.0173 (4) | |
| H2 | 0.263 (3) | 0.4122 (18) | −0.076 (2) | 0.021* | |
| C10 | 0.4555 (3) | 0.20854 (17) | −0.0595 (2) | 0.0223 (5) | |
| H4 | 0.468 (3) | 0.156 (2) | −0.099 (2) | 0.027* | |
| C7 | 0.4298 (2) | 0.37017 (14) | 0.07151 (17) | 0.0145 (4) | |
| C9 | 0.3417 (3) | 0.28035 (17) | −0.11190 (19) | 0.0217 (4) | |
| H3 | 0.274 (3) | 0.2759 (19) | −0.195 (2) | 0.026* | |
| C13 | 0.3272 (3) | 0.54328 (17) | 0.0970 (2) | 0.0232 (5) | |
| H9 | 0.351 (3) | 0.595 (2) | 0.152 (2) | 0.028* | |
| H7 | 0.340 (3) | 0.5618 (19) | 0.027 (2) | 0.028* | |
| H8 | 0.222 (3) | 0.5245 (19) | 0.076 (2) | 0.028* | |
| H1 | 0.663 (4) | 0.511 (2) | 0.426 (3) | 0.050 (10)* | |
| Br1 | 0.92699 (2) | 0.416206 (15) | 0.738904 (17) | 0.01764 (6) | |
| Br2 | 0.98903 (2) | 0.811177 (15) | 0.427719 (17) | 0.01869 (6) | |
| O1 | 1.19471 (16) | 0.56928 (11) | 0.79086 (12) | 0.0180 (3) | |
| O2 | 1.22536 (16) | 0.73058 (10) | 0.67034 (12) | 0.0186 (3) | |
| O3 | 0.73311 (16) | 0.64428 (11) | 0.37219 (12) | 0.0198 (3) | |
| C5 | 0.9790 (2) | 0.69726 (14) | 0.51628 (17) | 0.0150 (4) | |
| O4 | 0.70848 (17) | 0.48853 (11) | 0.48976 (14) | 0.0197 (3) | |
| C1 | 0.8359 (2) | 0.54445 (15) | 0.54043 (18) | 0.0152 (4) | |
| C6 | 0.8462 (2) | 0.63450 (15) | 0.46801 (17) | 0.0149 (4) | |
| C4 | 1.1029 (2) | 0.67882 (14) | 0.62391 (18) | 0.0139 (4) | |
| C3 | 1.0879 (2) | 0.58650 (14) | 0.69581 (17) | 0.0143 (4) | |
| C2 | 0.9474 (2) | 0.52459 (14) | 0.64757 (17) | 0.0145 (4) |
| U11 | U22 | U33 | U12 | U13 | U23 | |
| O5 | 0.0225 (8) | 0.0205 (7) | 0.0161 (7) | −0.0024 (6) | 0.0059 (6) | −0.0021 (6) |
| N1 | 0.0126 (8) | 0.0165 (8) | 0.0135 (8) | 0.0001 (6) | 0.0014 (7) | 0.0008 (7) |
| C12 | 0.0157 (10) | 0.0161 (10) | 0.0184 (10) | −0.0023 (7) | 0.0088 (8) | 0.0005 (8) |
| C11 | 0.0178 (10) | 0.0179 (10) | 0.0219 (11) | 0.0044 (8) | 0.0048 (9) | 0.0002 (8) |
| C8 | 0.0129 (10) | 0.0206 (10) | 0.0158 (10) | 0.0007 (8) | 0.0024 (8) | 0.0035 (8) |
| C10 | 0.0277 (12) | 0.0212 (11) | 0.0185 (11) | 0.0005 (9) | 0.0093 (9) | −0.0056 (9) |
| C7 | 0.0138 (9) | 0.0143 (9) | 0.0158 (10) | −0.0004 (7) | 0.0062 (8) | 0.0011 (8) |
| C9 | 0.0242 (11) | 0.0246 (11) | 0.0137 (10) | −0.0027 (9) | 0.0045 (9) | −0.0002 (8) |
| C13 | 0.0271 (12) | 0.0209 (11) | 0.0249 (12) | 0.0057 (9) | 0.0135 (10) | 0.0023 (9) |
| Br1 | 0.01649 (11) | 0.01824 (11) | 0.01617 (11) | −0.00241 (7) | 0.00395 (8) | 0.00493 (7) |
| Br2 | 0.02145 (12) | 0.01616 (11) | 0.01540 (11) | −0.00364 (7) | 0.00360 (9) | 0.00339 (7) |
| O1 | 0.0164 (7) | 0.0188 (7) | 0.0144 (7) | −0.0007 (5) | 0.0011 (6) | 0.0018 (6) |
| O2 | 0.0172 (7) | 0.0158 (7) | 0.0185 (7) | −0.0026 (5) | 0.0020 (6) | 0.0016 (6) |
| O3 | 0.0182 (7) | 0.0229 (8) | 0.0137 (7) | −0.0020 (6) | 0.0008 (6) | 0.0032 (6) |
| C5 | 0.0184 (10) | 0.0128 (9) | 0.0129 (9) | −0.0001 (7) | 0.0051 (8) | 0.0021 (7) |
| O4 | 0.0168 (8) | 0.0208 (8) | 0.0154 (7) | −0.0058 (6) | −0.0008 (6) | 0.0026 (6) |
| C1 | 0.0155 (10) | 0.0153 (9) | 0.0154 (10) | −0.0005 (7) | 0.0065 (8) | −0.0014 (8) |
| C6 | 0.0156 (10) | 0.0165 (10) | 0.0127 (9) | 0.0016 (7) | 0.0057 (8) | 0.0005 (8) |
| C4 | 0.0147 (10) | 0.0122 (9) | 0.0152 (10) | 0.0003 (7) | 0.0061 (8) | −0.0013 (7) |
| C3 | 0.0164 (10) | 0.0136 (9) | 0.0145 (10) | 0.0013 (7) | 0.0077 (8) | −0.0015 (7) |
| C2 | 0.0167 (10) | 0.0130 (9) | 0.0151 (9) | −0.0001 (7) | 0.0075 (8) | 0.0012 (7) |
| O5—C12 | 1.209 (2) | C13—H7 | 0.94 (3) |
| N1—C11 | 1.323 (3) | C13—H8 | 0.93 (3) |
| N1—C7 | 1.353 (2) | Br1—C2 | 1.8826 (19) |
| N1—H6 | 0.91 (3) | Br2—C5 | 1.8922 (19) |
| C12—C13 | 1.491 (3) | O1—C3 | 1.221 (2) |
| C12—C7 | 1.504 (3) | O2—C4 | 1.253 (2) |
| C11—C10 | 1.390 (3) | O3—C6 | 1.239 (2) |
| C11—H5 | 0.96 (3) | C5—C4 | 1.392 (3) |
| C8—C7 | 1.381 (3) | C5—C6 | 1.407 (3) |
| C8—C9 | 1.390 (3) | O4—C1 | 1.322 (2) |
| C8—H2 | 0.89 (2) | O4—H1 | 0.79 (3) |
| C10—C9 | 1.381 (3) | C1—C2 | 1.344 (3) |
| C10—H4 | 0.88 (3) | C1—C6 | 1.520 (3) |
| C9—H3 | 0.97 (3) | C4—C3 | 1.552 (3) |
| C13—H9 | 0.93 (3) | C3—C2 | 1.451 (3) |
| C11—N1—C7 | 122.38 (18) | H9—C13—H7 | 112 (2) |
| C11—N1—H6 | 119.2 (18) | C12—C13—H8 | 107.8 (16) |
| C7—N1—H6 | 118.2 (18) | H9—C13—H8 | 110 (2) |
| O5—C12—C13 | 123.61 (19) | H7—C13—H8 | 107 (2) |
| O5—C12—C7 | 118.77 (18) | C4—C5—C6 | 123.42 (18) |
| C13—C12—C7 | 117.62 (18) | C4—C5—Br2 | 119.00 (14) |
| N1—C11—C10 | 120.53 (19) | C6—C5—Br2 | 117.57 (14) |
| N1—C11—H5 | 115.3 (15) | C1—O4—H1 | 107 (2) |
| C10—C11—H5 | 124.2 (15) | O4—C1—C2 | 123.31 (19) |
| C7—C8—C9 | 119.83 (19) | O4—C1—C6 | 114.51 (17) |
| C7—C8—H2 | 117.2 (16) | C2—C1—C6 | 122.18 (17) |
| C9—C8—H2 | 122.9 (16) | O3—C6—C5 | 127.49 (19) |
| C9—C10—C11 | 118.8 (2) | O3—C6—C1 | 114.86 (17) |
| C9—C10—H4 | 122.0 (16) | C5—C6—C1 | 117.65 (17) |
| C11—C10—H4 | 119.1 (16) | O2—C4—C5 | 126.44 (18) |
| N1—C7—C8 | 119.03 (18) | O2—C4—C3 | 116.07 (17) |
| N1—C7—C12 | 116.30 (17) | C5—C4—C3 | 117.48 (17) |
| C8—C7—C12 | 124.67 (18) | O1—C3—C2 | 122.78 (18) |
| C10—C9—C8 | 119.39 (19) | O1—C3—C4 | 118.58 (17) |
| C10—C9—H3 | 120.6 (15) | C2—C3—C4 | 118.64 (17) |
| C8—C9—H3 | 119.9 (15) | C1—C2—C3 | 120.51 (18) |
| C12—C13—H9 | 109.4 (16) | C1—C2—Br1 | 121.41 (15) |
| C12—C13—H7 | 110.4 (16) | C3—C2—Br1 | 118.08 (14) |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O4—H1···O5 | 0.78 (3) | 2.20 (3) | 2.798 (2) | 134 (3) |
| N1—H6···O2i | 0.91 (3) | 1.83 (3) | 2.673 (2) | 154 (3) |
| Symmetry codes: (i) −x+2, −y+1, −z+1. |
| D—H···A | D—H | H···A | D···A | D—H···A |
| O4—H1···O5 | 0.78 (3) | 2.20 (3) | 2.798 (2) | 134 (3) |
| N1—H6···O2i | 0.91 (3) | 1.83 (3) | 2.673 (2) | 154 (3) |
| Symmetry codes: (i) −x+2, −y+1, −z+1. |
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The stucture of the molecular proton-transfer salt of bromanilic acid with 2-acetylpyridine at 100 K is reported (Fig. 1). A proton is transferred from the bromanilic acid molecule to the N atom on the acetylpyridine (Fig. 1). All previously reported structures containing bromanilic acid have shown the tendency for extended chains of molecules to form. In this case, hydrogen-bonded rings are formed between alternating cations and anions (Fig. 2) and these rings are held together to form a three-dimensional structure by one Br···O close contact of 3.243 (2)Å (cf the sum of the van der Waals radii for Br and O of 3.37Å) and one on the limit of the sum of the van der Waals radii of of 3.359 (2)Å (Fig. 3). The deprotonated hydroxyl group on the bromanilic acid molecule is stabilized by forming a moderate hydrogen bond [2.673 (2)Å] with the N atom on the 2-acetylpyridine molecule to which the proton has been transferred, and a short O···Br contact with another bromanilic acid molecule. The C—O bond length to the deprotonated oxygen is notably shortened compared to that to the protonated hydroxyl group [1.253 (2)Å versus 1.322 (2)Å]. The longer of the two O···Br close contacts is to the C═O group on the bromanilic acid [C═O bond length 1.221 (2)Å].