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Acta Crystallogr Sect E Struct Rep Online. 2008 November 1; 64(Pt 11): o2230.
Published online 2008 October 31. doi:  10.1107/S1600536808034934
PMCID: PMC2959658

2-Amino­pyridinium 4-hydroxy­benzoate

Abstract

In the title compound, C5H7N2 +·C7H5O3 , the carboxyl­ate mean plane of the 4-hydroxy­benzoate anion is twisted by 8.78 (5)° from the attached ring. The cations and anions are linked via O—H(...)O, N—H(...)O and C—H(...)O hydrogen bonds, forming a three-dimensional network. In addition, π–π inter­actions involving the benzene and pyridinium rings, with centroid–centroid distances of 3.5500 (6) and 3.6594 (6) Å, are observed.

Related literature

For the applications of 2-amino­pyridine, see: Windholz (1976 [triangle]). For related structures, see: Chao et al. (1975 [triangle]); Heath et al. (1992 [triangle]); Jebas & Balasubramanian (2006 [triangle]); Joanna & Zaworotko (2005 [triangle]); Smith et al. (2000 [triangle]).

An external file that holds a picture, illustration, etc.
Object name is e-64-o2230-scheme1.jpg

Experimental

Crystal data

  • C5H7N2 +·C7H5O3
  • M r = 232.24
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o2230-efi1.jpg
  • a = 10.0647 (2) Å
  • b = 10.9369 (2) Å
  • c = 10.7985 (2) Å
  • β = 111.036 (1)°
  • V = 1109.44 (4) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.10 mm−1
  • T = 100.0 (1) K
  • 0.34 × 0.29 × 0.17 mm

Data collection

  • Bruker SMART APEXII CCD area-detector diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2005 [triangle]) T min = 0.966, T max = 0.983
  • 22398 measured reflections
  • 5078 independent reflections
  • 3835 reflections with I > 2σ(I)
  • R int = 0.029

Refinement

  • R[F 2 > 2σ(F 2)] = 0.049
  • wR(F 2) = 0.140
  • S = 1.02
  • 5078 reflections
  • 158 parameters
  • 1 restraint
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.50 e Å−3
  • Δρmin = −0.21 e Å−3

Data collection: APEX2 (Bruker, 2005 [triangle]); cell refinement: APEX2 and SAINT (Bruker, 2005 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2003 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536808034934/ci2696sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808034934/ci2696Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

HKF and SRJ thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. SRJ thanks Universiti Sains Malaysia for a post–doctoral research fellowship. CKQ thanks Universiti Sains Malaysia for a student assistanceship.

supplementary crystallographic information

Comment

2-Aminopyridine is used in the manufacture of pharmaceuticals, especially antihistaminic drugs (Windholz, 1976). As an extension of our systematic study of hydrogen bonding patterns of 2-aminopyridine with aromatic carboxylic acids, the title compound was synthesized and its crystal structure determined.

The asymmetric unit contains one 2-aminopyridinium cation and 4-hydroxybenzoate anion. The proton transfer from the carboxyl group to atom N1 of 2-aminopyridine resulted in the widening of C8—N1—C12 angle of the pyridinium ring to 122.35°, compared to the corresponding angle of 117.7 (1)° in neutral 2-aminopyridine (Chao et al., 1975). Similar feature is observed in various 2-aminopyridine acid complexes (Joanna & Zaworotko, 2005; Smith et al., 2000). The bond distances and angles in the title compound are comparable to those in various 2-aminopyridine acid complexes and 4-hydroxybenzoic acid (Joanna & Zaworotko, 2005; Heath et al., 1992).

The 2-aminopyridinium cation is essentially planar, with a maximum deviation of 0.016 (1) Å for atom N1. In the 4-hydroxybenzoate anion, the carboxylate group is twisted slightly from the attached ring; the dihedral angle between C1-C6 and O2/O3/C6/C7 planes is 8.78 (5)°.

The crystal packing is consolidated by intermolecular O—H···O, N—H···O and C—H···O hydrogen bonds (Table 1). These hydrogen bonds link the molecules into a three-dimensional network. The packing is further strengthened by π-π interactions involving the benzene (centroid Cg1) and pyridinium (centroid Cg2) rings, with Cg1···Cg2iv = 3.6594 (6) Å and Cg2···Cg2v = 3.5500 (6) Å [symmetry code: (iv) 1-x, 1-y, 1-z; (v) -x, 1-y, 1-z].

Experimental

2-Aminopyridine and 4-hydroxybenzoic acid were mixed in methanol in a 1:1 molar ratio. The clear colourless solution obtained was allowed to evaporate slowly. Colourless crystals were obtained after a week.

Refinement

H atoms were placed in calculated positions, with C-H = 0.93 Å, N-H = 0.86 Å and O-H = 0.82 Å and refined using a riding model with Uiso(H) = 1.2Ueq(C,N) and 1.5Ueq(O). Atom H1N1 was located in a difference map and was refined with an N-H distance restraint of 0.86 Å.

Figures

Fig. 1.
The molecular structure of the title compound, showing 50% probability displacement ellipsoids and the atom numbering scheme. The dashed line indicates a hydrogen bond.
Fig. 2.
The crystal packing of the title compound, viewed along the c axis. Hydrogen bonds are shown as dashed lines.

Crystal data

C5H7N2+·C7H5O3F(000) = 488
Mr = 232.24Dx = 1.390 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 6837 reflections
a = 10.0647 (2) Åθ = 2.8–35.6°
b = 10.9369 (2) ŵ = 0.10 mm1
c = 10.7985 (2) ÅT = 100 K
β = 111.036 (1)°Block, colourless
V = 1109.44 (4) Å30.34 × 0.29 × 0.17 mm
Z = 4

Data collection

Bruker SMART APEXII CCD area-detector diffractometer5078 independent reflections
Radiation source: fine-focus sealed tube3835 reflections with I > 2σ(I)
graphiteRint = 0.030
[var phi] and ω scansθmax = 35.6°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Bruker, 2005)h = −16→11
Tmin = 0.966, Tmax = 0.983k = −17→17
22398 measured reflectionsl = −16→17

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.049Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.140H atoms treated by a mixture of independent and constrained refinement
S = 1.02w = 1/[σ2(Fo2) + (0.0746P)2 + 0.2186P] where P = (Fo2 + 2Fc2)/3
5078 reflections(Δ/σ)max = 0.001
158 parametersΔρmax = 0.50 e Å3
1 restraintΔρmin = −0.21 e Å3

Special details

Experimental. The data was collected with the Oxford Cyrosystem Cobra low-temperature attachment.
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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/Ueq
O10.52173 (8)0.67777 (7)0.56764 (7)0.02345 (16)
H1O10.54350.64300.63950.035*
O20.97943 (7)1.10528 (6)0.70095 (6)0.01770 (14)
O30.88217 (8)1.12535 (7)0.48165 (6)0.02051 (14)
N10.06716 (8)0.30978 (7)0.51061 (7)0.01683 (15)
N20.18939 (9)0.28645 (8)0.73537 (8)0.02239 (17)
H1N20.13540.22540.73480.027*
H2N20.25500.30850.80820.027*
C10.81342 (9)0.89872 (8)0.69825 (8)0.01647 (16)
H1A0.88730.91800.77690.020*
C20.72397 (10)0.80096 (9)0.69536 (8)0.01740 (16)
H2A0.73870.75480.77140.021*
C30.61195 (10)0.77231 (9)0.57782 (9)0.01771 (16)
C40.59084 (11)0.84236 (10)0.46429 (9)0.02258 (19)
H4A0.51570.82430.38620.027*
C50.68141 (10)0.93876 (9)0.46745 (9)0.02087 (18)
H5A0.66730.98420.39100.025*
C60.79383 (9)0.96844 (8)0.58454 (8)0.01518 (15)
C70.89111 (9)1.07305 (8)0.58888 (8)0.01503 (15)
C80.03894 (10)0.36798 (9)0.39292 (9)0.01886 (17)
H8A−0.03480.33990.31830.023*
C90.11667 (11)0.46682 (9)0.38189 (10)0.02141 (18)
H9A0.09680.50680.30120.026*
C100.22817 (11)0.50629 (9)0.49691 (10)0.02254 (19)
H10A0.28360.57280.49190.027*
C110.25595 (10)0.44821 (9)0.61585 (10)0.02098 (18)
H11A0.32970.47500.69110.025*
C120.17140 (10)0.34698 (9)0.62328 (9)0.01766 (16)
H1N10.0145 (17)0.2453 (12)0.5101 (19)0.051 (5)*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.0264 (4)0.0269 (4)0.0164 (3)−0.0110 (3)0.0069 (3)0.0002 (3)
O20.0180 (3)0.0203 (3)0.0128 (3)−0.0017 (2)0.0032 (2)−0.0020 (2)
O30.0219 (3)0.0218 (3)0.0143 (3)−0.0048 (3)0.0023 (2)0.0040 (2)
N10.0170 (3)0.0179 (3)0.0144 (3)−0.0029 (3)0.0042 (3)−0.0020 (3)
N20.0227 (4)0.0254 (4)0.0147 (3)−0.0055 (3)0.0015 (3)−0.0015 (3)
C10.0167 (4)0.0186 (4)0.0127 (3)−0.0001 (3)0.0036 (3)0.0001 (3)
C20.0189 (4)0.0194 (4)0.0136 (3)−0.0011 (3)0.0056 (3)0.0016 (3)
C30.0192 (4)0.0198 (4)0.0151 (3)−0.0037 (3)0.0073 (3)−0.0011 (3)
C40.0230 (4)0.0288 (5)0.0126 (3)−0.0093 (4)0.0024 (3)0.0002 (3)
C50.0225 (4)0.0245 (5)0.0133 (3)−0.0053 (3)0.0036 (3)0.0023 (3)
C60.0159 (3)0.0164 (4)0.0127 (3)0.0000 (3)0.0044 (3)0.0002 (3)
C70.0154 (3)0.0156 (4)0.0129 (3)0.0010 (3)0.0037 (3)0.0001 (3)
C80.0185 (4)0.0218 (4)0.0159 (4)−0.0018 (3)0.0057 (3)−0.0008 (3)
C90.0226 (4)0.0220 (4)0.0206 (4)−0.0025 (3)0.0090 (3)0.0011 (3)
C100.0210 (4)0.0205 (4)0.0276 (4)−0.0052 (3)0.0105 (4)−0.0025 (3)
C110.0169 (4)0.0213 (4)0.0229 (4)−0.0034 (3)0.0049 (3)−0.0046 (3)
C120.0162 (4)0.0190 (4)0.0163 (4)−0.0005 (3)0.0040 (3)−0.0032 (3)

Geometric parameters (Å, °)

O1—C31.3543 (11)C3—C41.3957 (13)
O1—H1O10.8200C4—C51.3861 (13)
O2—C71.2675 (10)C4—H4A0.93
O3—C71.2654 (10)C5—C61.3990 (12)
N1—C121.3528 (11)C5—H5A0.93
N1—C81.3571 (12)C6—C71.4956 (12)
N1—H1N10.881 (9)C8—C91.3644 (13)
N2—C121.3338 (12)C8—H8A0.93
N2—H1N20.86C9—C101.4099 (14)
N2—H2N20.86C9—H9A0.93
C1—C21.3908 (13)C10—C111.3687 (14)
C1—C61.3980 (12)C10—H10A0.93
C1—H1A0.93C11—C121.4161 (13)
C2—C31.3975 (12)C11—H11A0.93
C2—H2A0.93
C3—O1—H1O1109.5C1—C6—C5118.72 (8)
C12—N1—C8122.35 (8)C1—C6—C7120.36 (8)
C12—N1—H1N1121.1 (13)C5—C6—C7120.92 (8)
C8—N1—H1N1116.5 (13)O3—C7—O2122.89 (8)
C12—N2—H1N2120.0O3—C7—C6119.10 (7)
C12—N2—H2N2120.0O2—C7—C6118.00 (7)
H1N2—N2—H2N2120.0N1—C8—C9121.30 (9)
C2—C1—C6120.90 (8)N1—C8—H8A119.3
C2—C1—H1A119.5C9—C8—H8A119.3
C6—C1—H1A119.5C8—C9—C10117.75 (9)
C1—C2—C3119.83 (8)C8—C9—H9A121.1
C1—C2—H2A120.1C10—C9—H9A121.1
C3—C2—H2A120.1C11—C10—C9120.96 (9)
O1—C3—C4117.49 (8)C11—C10—H10A119.5
O1—C3—C2122.94 (8)C9—C10—H10A119.5
C4—C3—C2119.57 (8)C10—C11—C12119.44 (9)
C5—C4—C3120.30 (8)C10—C11—H11A120.3
C5—C4—H4A119.9C12—C11—H11A120.3
C3—C4—H4A119.9N2—C12—N1118.41 (8)
C4—C5—C6120.67 (8)N2—C12—C11123.43 (8)
C4—C5—H5A119.7N1—C12—C11118.17 (8)
C6—C5—H5A119.7
C6—C1—C2—C3−0.63 (14)C5—C6—C7—O3−8.78 (13)
C1—C2—C3—O1179.36 (9)C1—C6—C7—O2−8.40 (12)
C1—C2—C3—C4−0.07 (14)C5—C6—C7—O2171.26 (9)
O1—C3—C4—C5−178.61 (9)C12—N1—C8—C91.07 (14)
C2—C3—C4—C50.84 (15)N1—C8—C9—C100.35 (14)
C3—C4—C5—C6−0.92 (16)C8—C9—C10—C11−0.87 (15)
C2—C1—C6—C50.55 (13)C9—C10—C11—C120.02 (15)
C2—C1—C6—C7−179.78 (8)C8—N1—C12—N2178.22 (9)
C4—C5—C6—C10.22 (14)C8—N1—C12—C11−1.90 (14)
C4—C5—C6—C7−179.44 (9)C10—C11—C12—N2−178.79 (9)
C1—C6—C7—O3171.56 (8)C10—C11—C12—N11.33 (14)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
O1—H1O1···O2i0.821.862.6257 (9)154
N2—H1N2···O2ii0.861.982.8224 (11)167
N2—H2N2···O3iii0.861.992.8396 (11)171
N1—H1N1···O3ii0.88 (1)1.81 (1)2.6861 (10)169 (2)
C10—H10A···O10.932.513.3482 (14)149
C11—H11A···O2i0.932.343.1899 (12)152

Symmetry codes: (i) −x+3/2, y−1/2, −z+3/2; (ii) x−1, y−1, z; (iii) x−1/2, −y+3/2, z+1/2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: CI2696).

References

  • Bruker (2005). APEX2, SAINT and SADABS Bruker AXS Inc., Madison, Wisconsin, USA.
  • Chao, M., Schemp, E. & Rosenstein, R. D. (1975). Acta Cryst. B31, 2922–2924.
  • Heath, E. A., Singh, P. & Ebisuzaki, Y. (1992). Acta Cryst. C48, 1960–1965.
  • Jebas, S. R. & Balasubramanian, T. (2006). Acta Cryst. E62, o2209–o2211.
  • Joanna, A. B. & Zaworotko, M. J. (2005). Cryst. Growth Des.5, 1169–1179.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Smith, G., Bott, R. C. & Wermuth, U. D. (2000). Acta Cryst. C56, 1505–1506. [PubMed]
  • Spek, A. L. (2003). J. Appl. Cryst.36, 7–13.
  • Windholz, M. (1976). The Merck Index, 9th ed. Boca Raton, USA: Merck & Co. Inc.

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