organic compounds
2-Amino-4-methylpyridinium 3-hydroxybenzoate
aSchool of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
*Correspondence e-mail: arazaki@usm.my
In the title salt, C6H9N2+·C7H5O3−, the anion is essentially planar, with a dihedral angle of 2.72 (17)° between the benzene ring and the carboxylate group. In the crystal, the anions are connected by O—H⋯O hydrogen bonds, forming a 41 helical chain along the c axis. The protonated N atom and the 2-amino group of the cation are hydrogen bonded to the carboxylate O atoms of the anion via a pair of N—H⋯O hydrogen bonds with an R22(8) ring motif. The ion pairs are further connected via another N—H⋯O hydrogen bond, resulting in a three-dimensional network.
Related literature
For the role of hydrogen bonding in crystal engineering, see: Goswami & Ghosh (1997); Goswami et al. (1998); Lehn (1992). For related structures, see: Kvick & Noordik (1977). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2009); cell SAINT (Bruker, 2009); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536813016310/is5282sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536813016310/is5282Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536813016310/is5282Isup3.cml
Hot methanol solution (20 ml) of 2-amino-4-methylpyridine (54 mg, Aldrich) and 3-hydroxybenzoic acid (35 mg, Merck) were mixed and warmed over a heating magnetic-stirrer hotplate for a few minutes. The resulting solution was allowed to cool slowly at room temperature and crystals of the title compound (I) appeared after a few days.
O- and N- bound H atoms were located in a difference Fourier map and allowed to be refined freely [O—H = 0.89 (2) Å and N—H = 0.88 (2) and 0.92 (2) Å]. The remaining H atoms were positioned geometrically (C—H = 0.95 or 0.98 Å) and were refined using a riding model, with Uiso(H) = 1.2Ueq(C) or 1.5Ueq(methyl C). A rotating-group model was used for the methyl group. One outlier (0 2 0) was omitted in the final refinement.
Hydrogen bonding plays a key role in molecular recognition (Goswami & Ghosh, 1997) and crystal engineering research (Goswami et al., 1998). The design of highly specific solid-state compounds is of considerable significance in organic chemistry due to important applications of these compounds in the development of new optical, magnetic and electronic systems (Lehn, 1992). In order to study some hydrogen bonding interactions, the synthesis and structure of the title salt, (I), is presented here.
The
(Fig. 1) contains one 2-amino-4-methylpyridinium cation and one 3-hydroxybenzoate anion. A proton is transfered from the carboxyl group to atom N1 of 2-amino-4-methylpyridine, resulting in the widening of C1–N1–C5 angle of the pyridinium ring to 122.25 (12)°, compared to the corresponding angle of 117.3 (1)° in neutral 2-amino-4-methylpyridine (Kvick & Noordik, 1977). The 2-amino-4-methylpyridinium cation is essentially planar, with a maximum deviation of 0.007 (1) Å for atom C5. The carboxylate group of the 3-hydroxybenzoate anion is slightly twisted from the attached ring with a dihedral angle between the C7–C12 ring and the O2/O3/C13 plane being 2.72 (17)°. The bond lengths and angles are normal (Allen et al., 1987).In the crystal packing (Fig. 2), the anions are connected by O1—H1O1···O2i hydrogen bonds (symmetry code in Table 1). The protonated N1 atom and the 2-amino group (N2) of the cation are hydrogen-bonded to the carboxylate oxygen atoms of the anion (O2 and O3, respectively) via a pair of intermolecular N1—H1N1···O2ii and N2—H1N2···O3ii hydrogen bonds (symmetry code in Table 1), forming an R22(8) (Bernstein et al., 1995) ring motif. These motifs are then connected via N2—H2N2···O3 hydrogen bond (Table 1), resulting in a three-dimensional network.
For the role of hydrogen bonding in crystal engineering, see: Goswami & Ghosh (1997); Goswami et al. (1998); Lehn (1992). For related structures, see: Kvick & Noordik (1977). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986).
Data collection: APEX2 (Bruker, 2009); cell
SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. The molecular structure of the title compound with atom labels with 50% probability displacement ellipsoids. | |
Fig. 2. The crystal packing of the title compound. The H atoms not involved in the intermolecular interactions (dashed lines) have been omitted for clarity. |
C6H9N2+·C7H5O3− | Dx = 1.304 Mg m−3 |
Mr = 246.26 | Mo Kα radiation, λ = 0.71073 Å |
Tetragonal, I41/a | Cell parameters from 9925 reflections |
Hall symbol: -I 4ad | θ = 2.6–30.0° |
a = 15.4435 (2) Å | µ = 0.09 mm−1 |
c = 21.0395 (3) Å | T = 100 K |
V = 5017.96 (12) Å3 | Block, colourless |
Z = 16 | 0.43 × 0.26 × 0.23 mm |
F(000) = 2080 |
Bruker SMART APEXII CCD area-detector diffractometer | 3702 independent reflections |
Radiation source: fine-focus sealed tube | 3092 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.058 |
φ and ω scans | θmax = 30.1°, θmin = 1.6° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −21→21 |
Tmin = 0.961, Tmax = 0.979 | k = −21→21 |
46924 measured reflections | l = −29→29 |
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)] = 0.060 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.130 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.10 | w = 1/[σ2(Fo2) + (0.0518P)2 + 5.0006P] where P = (Fo2 + 2Fc2)/3 |
3702 reflections | (Δ/σ)max = 0.001 |
180 parameters | Δρmax = 0.45 e Å−3 |
0 restraints | Δρmin = −0.30 e Å−3 |
C6H9N2+·C7H5O3− | Z = 16 |
Mr = 246.26 | Mo Kα radiation |
Tetragonal, I41/a | µ = 0.09 mm−1 |
a = 15.4435 (2) Å | T = 100 K |
c = 21.0395 (3) Å | 0.43 × 0.26 × 0.23 mm |
V = 5017.96 (12) Å3 |
Bruker SMART APEXII CCD area-detector diffractometer | 3702 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 3092 reflections with I > 2σ(I) |
Tmin = 0.961, Tmax = 0.979 | Rint = 0.058 |
46924 measured reflections |
R[F2 > 2σ(F2)] = 0.060 | 0 restraints |
wR(F2) = 0.130 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.10 | Δρmax = 0.45 e Å−3 |
3702 reflections | Δρmin = −0.30 e Å−3 |
180 parameters |
Experimental. The crystal was placed in the cold stream of an Oxford Cryosystems Cobra open-flow nitrogen cryostat (Cosier & Glazer, 1986) operating at 100.0 (1) K. |
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 | ||
N1 | 0.86599 (8) | 0.70451 (8) | 0.73009 (5) | 0.0194 (2) | |
N2 | 0.83258 (9) | 0.72622 (8) | 0.83600 (6) | 0.0248 (3) | |
C1 | 0.88264 (9) | 0.65309 (9) | 0.67916 (7) | 0.0225 (3) | |
H1A | 0.8954 | 0.6788 | 0.6392 | 0.027* | |
C2 | 0.88132 (10) | 0.56542 (9) | 0.68453 (7) | 0.0235 (3) | |
H2A | 0.8935 | 0.5299 | 0.6488 | 0.028* | |
C3 | 0.86144 (9) | 0.52768 (8) | 0.74423 (6) | 0.0196 (3) | |
C4 | 0.84480 (9) | 0.58047 (8) | 0.79506 (6) | 0.0196 (3) | |
H4A | 0.8312 | 0.5558 | 0.8352 | 0.024* | |
C5 | 0.84777 (9) | 0.67176 (9) | 0.78816 (6) | 0.0186 (3) | |
C6 | 0.86067 (10) | 0.43092 (9) | 0.75102 (7) | 0.0247 (3) | |
H6A | 0.8378 | 0.4153 | 0.7929 | 0.037* | |
H6B | 0.9198 | 0.4086 | 0.7467 | 0.037* | |
H6C | 0.8239 | 0.4056 | 0.7179 | 0.037* | |
O1 | 0.53366 (7) | 0.62983 (8) | 0.91513 (5) | 0.0265 (2) | |
O2 | 0.87586 (6) | 0.63112 (7) | 1.05329 (5) | 0.0220 (2) | |
O3 | 0.85543 (7) | 0.62684 (8) | 0.94864 (5) | 0.0278 (3) | |
C7 | 0.67779 (8) | 0.63135 (8) | 0.95960 (6) | 0.0174 (3) | |
H7A | 0.7030 | 0.6265 | 0.9186 | 0.021* | |
C8 | 0.58817 (9) | 0.63434 (9) | 0.96604 (6) | 0.0190 (3) | |
C9 | 0.55143 (9) | 0.64153 (10) | 1.02625 (7) | 0.0236 (3) | |
H9A | 0.4903 | 0.6436 | 1.0308 | 0.028* | |
C10 | 0.60424 (9) | 0.64573 (10) | 1.07952 (6) | 0.0234 (3) | |
H10A | 0.5789 | 0.6507 | 1.1205 | 0.028* | |
C11 | 0.69395 (9) | 0.64269 (9) | 1.07361 (6) | 0.0201 (3) | |
H11A | 0.7297 | 0.6455 | 1.1103 | 0.024* | |
C12 | 0.73072 (8) | 0.63549 (8) | 1.01339 (6) | 0.0163 (2) | |
C13 | 0.82751 (8) | 0.63125 (9) | 1.00454 (6) | 0.0182 (3) | |
H1O1 | 0.5651 (14) | 0.6250 (13) | 0.8797 (10) | 0.044 (6)* | |
H1N1 | 0.8684 (13) | 0.7633 (14) | 0.7223 (10) | 0.043 (6)* | |
H1N2 | 0.8428 (13) | 0.7814 (13) | 0.8286 (9) | 0.036 (5)* | |
H2N2 | 0.8309 (12) | 0.7032 (13) | 0.8744 (9) | 0.035 (5)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0252 (6) | 0.0171 (5) | 0.0158 (6) | 0.0003 (4) | 0.0020 (4) | 0.0011 (4) |
N2 | 0.0410 (7) | 0.0191 (6) | 0.0144 (6) | −0.0007 (5) | 0.0048 (5) | 0.0002 (5) |
C1 | 0.0297 (7) | 0.0241 (7) | 0.0137 (6) | 0.0018 (5) | 0.0038 (5) | 0.0017 (5) |
C2 | 0.0317 (7) | 0.0227 (7) | 0.0159 (7) | 0.0032 (5) | 0.0036 (5) | −0.0013 (5) |
C3 | 0.0214 (6) | 0.0179 (6) | 0.0194 (7) | 0.0010 (5) | −0.0018 (5) | 0.0004 (5) |
C4 | 0.0242 (6) | 0.0192 (6) | 0.0155 (6) | −0.0011 (5) | 0.0007 (5) | 0.0021 (5) |
C5 | 0.0201 (6) | 0.0204 (6) | 0.0154 (6) | −0.0001 (5) | 0.0009 (5) | 0.0012 (5) |
C6 | 0.0358 (8) | 0.0167 (6) | 0.0217 (7) | 0.0006 (5) | −0.0009 (6) | 0.0003 (5) |
O1 | 0.0195 (5) | 0.0455 (7) | 0.0145 (5) | 0.0015 (4) | −0.0043 (4) | −0.0043 (4) |
O2 | 0.0178 (4) | 0.0327 (5) | 0.0154 (5) | 0.0010 (4) | −0.0015 (4) | −0.0004 (4) |
O3 | 0.0201 (5) | 0.0490 (7) | 0.0143 (5) | 0.0031 (4) | 0.0022 (4) | 0.0033 (4) |
C7 | 0.0194 (6) | 0.0199 (6) | 0.0129 (6) | 0.0005 (5) | 0.0007 (5) | −0.0008 (5) |
C8 | 0.0197 (6) | 0.0226 (6) | 0.0147 (6) | 0.0004 (5) | −0.0028 (5) | −0.0024 (5) |
C9 | 0.0164 (6) | 0.0354 (8) | 0.0189 (7) | 0.0000 (5) | 0.0004 (5) | −0.0041 (6) |
C10 | 0.0205 (6) | 0.0371 (8) | 0.0127 (6) | 0.0008 (5) | 0.0025 (5) | −0.0033 (5) |
C11 | 0.0189 (6) | 0.0288 (7) | 0.0128 (6) | −0.0004 (5) | −0.0018 (5) | −0.0014 (5) |
C12 | 0.0168 (6) | 0.0176 (6) | 0.0146 (6) | 0.0005 (4) | −0.0001 (4) | 0.0010 (4) |
C13 | 0.0168 (6) | 0.0220 (6) | 0.0157 (6) | 0.0007 (5) | 0.0007 (5) | 0.0015 (5) |
N1—C5 | 1.3521 (17) | C6—H6C | 0.9800 |
N1—C1 | 1.3582 (18) | O1—C8 | 1.3641 (16) |
N1—H1N1 | 0.92 (2) | O1—H1O1 | 0.89 (2) |
N2—C5 | 1.3326 (18) | O2—C13 | 1.2686 (16) |
N2—H1N2 | 0.88 (2) | O3—C13 | 1.2546 (16) |
N2—H2N2 | 0.88 (2) | C7—C8 | 1.3914 (18) |
C1—C2 | 1.359 (2) | C7—C12 | 1.3975 (18) |
C1—H1A | 0.9500 | C7—H7A | 0.9500 |
C2—C3 | 1.4184 (19) | C8—C9 | 1.3924 (19) |
C2—H2A | 0.9500 | C9—C10 | 1.3876 (19) |
C3—C4 | 1.3691 (19) | C9—H9A | 0.9500 |
C3—C6 | 1.5012 (19) | C10—C11 | 1.3918 (19) |
C4—C5 | 1.4180 (18) | C10—H10A | 0.9500 |
C4—H4A | 0.9500 | C11—C12 | 1.3929 (18) |
C6—H6A | 0.9800 | C11—H11A | 0.9500 |
C6—H6B | 0.9800 | C12—C13 | 1.5078 (18) |
C5—N1—C1 | 122.25 (12) | H6A—C6—H6C | 109.5 |
C5—N1—H1N1 | 122.5 (13) | H6B—C6—H6C | 109.5 |
C1—N1—H1N1 | 115.3 (14) | C8—O1—H1O1 | 108.9 (14) |
C5—N2—H1N2 | 116.4 (13) | C8—C7—C12 | 120.09 (12) |
C5—N2—H2N2 | 116.2 (13) | C8—C7—H7A | 120.0 |
H1N2—N2—H2N2 | 123.9 (18) | C12—C7—H7A | 120.0 |
N1—C1—C2 | 120.95 (13) | O1—C8—C7 | 122.39 (12) |
N1—C1—H1A | 119.5 | O1—C8—C9 | 117.83 (12) |
C2—C1—H1A | 119.5 | C7—C8—C9 | 119.77 (12) |
C1—C2—C3 | 119.10 (13) | C10—C9—C8 | 119.93 (13) |
C1—C2—H2A | 120.5 | C10—C9—H9A | 120.0 |
C3—C2—H2A | 120.5 | C8—C9—H9A | 120.0 |
C4—C3—C2 | 119.20 (12) | C9—C10—C11 | 120.76 (13) |
C4—C3—C6 | 121.12 (12) | C9—C10—H10A | 119.6 |
C2—C3—C6 | 119.67 (12) | C11—C10—H10A | 119.6 |
C3—C4—C5 | 120.39 (12) | C10—C11—C12 | 119.32 (12) |
C3—C4—H4A | 119.8 | C10—C11—H11A | 120.3 |
C5—C4—H4A | 119.8 | C12—C11—H11A | 120.3 |
N2—C5—N1 | 118.89 (12) | C11—C12—C7 | 120.12 (12) |
N2—C5—C4 | 122.99 (12) | C11—C12—C13 | 121.33 (12) |
N1—C5—C4 | 118.11 (12) | C7—C12—C13 | 118.55 (12) |
C3—C6—H6A | 109.5 | O3—C13—O2 | 123.75 (12) |
C3—C6—H6B | 109.5 | O3—C13—C12 | 117.31 (12) |
H6A—C6—H6B | 109.5 | O2—C13—C12 | 118.93 (12) |
C3—C6—H6C | 109.5 | ||
C5—N1—C1—C2 | 0.2 (2) | O1—C8—C9—C10 | 179.56 (13) |
N1—C1—C2—C3 | 0.6 (2) | C7—C8—C9—C10 | 0.0 (2) |
C1—C2—C3—C4 | −0.5 (2) | C8—C9—C10—C11 | −0.1 (2) |
C1—C2—C3—C6 | −179.36 (14) | C9—C10—C11—C12 | 0.1 (2) |
C2—C3—C4—C5 | −0.3 (2) | C10—C11—C12—C7 | 0.0 (2) |
C6—C3—C4—C5 | 178.53 (13) | C10—C11—C12—C13 | −179.53 (13) |
C1—N1—C5—N2 | 179.63 (13) | C8—C7—C12—C11 | 0.0 (2) |
C1—N1—C5—C4 | −1.0 (2) | C8—C7—C12—C13 | 179.47 (12) |
C3—C4—C5—N2 | −179.66 (14) | C11—C12—C13—O3 | −178.37 (13) |
C3—C4—C5—N1 | 1.0 (2) | C7—C12—C13—O3 | 2.12 (19) |
C12—C7—C8—O1 | −179.46 (12) | C11—C12—C13—O2 | 2.58 (19) |
C12—C7—C8—C9 | 0.0 (2) | C7—C12—C13—O2 | −176.92 (12) |
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O1···O2i | 0.89 (2) | 1.81 (2) | 2.6970 (15) | 172 (2) |
N1—H1N1···O2ii | 0.92 (2) | 1.81 (2) | 2.7221 (15) | 172 (2) |
N2—H1N2···O3ii | 0.88 (2) | 1.91 (2) | 2.7852 (16) | 170.6 (19) |
N2—H2N2···O3 | 0.883 (19) | 1.994 (19) | 2.8454 (17) | 161.7 (18) |
Symmetry codes: (i) −y+5/4, x−1/4, z−1/4; (ii) y+1/4, −x+7/4, −z+7/4. |
Experimental details
Crystal data | |
Chemical formula | C6H9N2+·C7H5O3− |
Mr | 246.26 |
Crystal system, space group | Tetragonal, I41/a |
Temperature (K) | 100 |
a, c (Å) | 15.4435 (2), 21.0395 (3) |
V (Å3) | 5017.96 (12) |
Z | 16 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.43 × 0.26 × 0.23 |
Data collection | |
Diffractometer | Bruker SMART APEXII CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2009) |
Tmin, Tmax | 0.961, 0.979 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 46924, 3702, 3092 |
Rint | 0.058 |
(sin θ/λ)max (Å−1) | 0.706 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.060, 0.130, 1.10 |
No. of reflections | 3702 |
No. of parameters | 180 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.45, −0.30 |
Computer programs: APEX2 (Bruker, 2009), SAINT (Bruker, 2009), SHELXTL (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
O1—H1O1···O2i | 0.89 (2) | 1.81 (2) | 2.6970 (15) | 172 (2) |
N1—H1N1···O2ii | 0.92 (2) | 1.81 (2) | 2.7221 (15) | 172 (2) |
N2—H1N2···O3ii | 0.88 (2) | 1.91 (2) | 2.7852 (16) | 170.6 (19) |
N2—H2N2···O3 | 0.883 (19) | 1.994 (19) | 2.8454 (17) | 161.7 (18) |
Symmetry codes: (i) −y+5/4, x−1/4, z−1/4; (ii) y+1/4, −x+7/4, −z+7/4. |
Footnotes
‡Thomson Reuters ResearcherID: A-5599-2009.
Acknowledgements
The authors thank the Malaysian Government and Universiti Sains Malaysia (USM) for the research facilities and USM Short Term Grant, No. 304/PFIZIK/6312078 to conduct this work. KT thanks the Academy of Sciences for the Developing World and USM for the TWAS–USM fellowship.
References
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Hydrogen bonding plays a key role in molecular recognition (Goswami & Ghosh, 1997) and crystal engineering research (Goswami et al., 1998). The design of highly specific solid-state compounds is of considerable significance in organic chemistry due to important applications of these compounds in the development of new optical, magnetic and electronic systems (Lehn, 1992). In order to study some hydrogen bonding interactions, the synthesis and structure of the title salt, (I), is presented here.
The asymmetric unit (Fig. 1) contains one 2-amino-4-methylpyridinium cation and one 3-hydroxybenzoate anion. A proton is transfered from the carboxyl group to atom N1 of 2-amino-4-methylpyridine, resulting in the widening of C1–N1–C5 angle of the pyridinium ring to 122.25 (12)°, compared to the corresponding angle of 117.3 (1)° in neutral 2-amino-4-methylpyridine (Kvick & Noordik, 1977). The 2-amino-4-methylpyridinium cation is essentially planar, with a maximum deviation of 0.007 (1) Å for atom C5. The carboxylate group of the 3-hydroxybenzoate anion is slightly twisted from the attached ring with a dihedral angle between the C7–C12 ring and the O2/O3/C13 plane being 2.72 (17)°. The bond lengths and angles are normal (Allen et al., 1987).
In the crystal packing (Fig. 2), the anions are connected by O1—H1O1···O2i hydrogen bonds (symmetry code in Table 1). The protonated N1 atom and the 2-amino group (N2) of the cation are hydrogen-bonded to the carboxylate oxygen atoms of the anion (O2 and O3, respectively) via a pair of intermolecular N1—H1N1···O2ii and N2—H1N2···O3ii hydrogen bonds (symmetry code in Table 1), forming an R22(8) (Bernstein et al., 1995) ring motif. These motifs are then connected via N2—H2N2···O3 hydrogen bond (Table 1), resulting in a three-dimensional network.