organic compounds
2-Amino-4-methylpyridinium (E)-3-carboxyprop-2-enoate
aX-ray Crystallography Unit, School of Physics, Universiti Sains Malaysia, 11800 USM, Penang, Malaysia
*Correspondence e-mail: hkfun@usm.my
In the title salt, C6H9N2+·C4H3O4−, the dihedral angle between the pyridine ring and the plane formed by the hydrogen fumarate anion is 85.67 (6)°. Excluding the amino and methyl groups, the atoms of the cation are coplanar, with a maximum deviation of 0.005 (1) Å. In the 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, forming an R22(8) ring motif. These motifs are further connected through N—H⋯O and C—H⋯O hydrogen bonds, leading to a supramolecular chain along the c axis. These chains are further cross-linked via a pair of O—H⋯O hydrogen bonds involving centrosymmetrically related hydrogen fumarate anions, forming a two-dimensional network parallel to (101). These planes are further interconnected by O—H⋯O interactions into a three-dimensional network.
Related literature
For applications of intermolecular interactions, see: Lam & Mak (2000). For related structures, see: Büyükgüngör & Odabąsoğlu (2006); Hosomi et al. (2000); Smith et al. (2007); Cao et al. (2004); Natarajan et al. (2009). For hydrogen-bond motifs, see: Bernstein et al. (1995). For reference 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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Refinement
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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/S1600536810026292/wn2399sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810026292/wn2399Isup2.hkl
A hot methanol solution (20 ml) of 2-amino-4-methylpyridine (54 mg, Aldrich) and fumaric acid (58 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 appeared after a few days.
All the H atoms were located from a difference Fourier map and refined freely [C—H = 0.953 (19)–1.027 (17) Å; N—H = 0.816 (19)–0.994 (18) Å and O—H = 0.93 (2) Å].
Intermolecular interactions are responsible for crystal packing and gaining an understanding of them allows us to comprehend collective properties and permits the design of new crystals with specific physical and chemical properties (Lam & Mak, 2000). Fumaric acid, a key intermediate in organic acid biosynthesis, is known to readily form adducts/complexes with other organic molecules. The crystal structures of 2,6-diaminopyridinium hydrogen fumarate (Büyükgüngör & Odabąsoǧlu, 2006), triethylammonium hydrogen fumarate (Hosomi et al., 2000), anhydrous guanidinium hydrogen fumarate (Smith et al., 2007), tiamulin hydrogen fumarate methanol (Cao et al., 2004) and glycinium hydrogen fumarate glycine solvate monohydrate (Natarajan et al., 2009) have been reported. The present study has been undertaken to study the hydrogen bonding patterns involving the hydrogen fumarate anion with the 2-amino-4-methylpyridinium cation.
The
of the title compound consists of a 2-amino-4-methyl pyridinium cation and a hydrogen fumarate anion (Fig. 1). In the 2-amino- 4-methylpyridinium cation, a wider than normal angle [C1—N1—C5 121.94 (11)°] is subtended at the protonated N1 atom. The C10—O3 bond distance of 1.2259 (16) Å is much shorter than the C10—O4 bond distance of 1.3224 (15) Å, suggesting that the carboxyl group is not deprotonated in the The dihedral angle between the pyridine ring and the plane formed by the hydrogen fumarate anion is 85.67 (6)°. Excluding amino and methyl groups, the atoms of the cation are coplanar, with a maximum deviation of 0.005 (1) Å for atom C2. The bond lengths (Allen et al., 1987) and angles are normal.In the crystal packing (Fig. 2), the protonated N1 atom and the 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of N—H···O hydrogen bonds, forming a R22(8) ring motif (Bernstein et al., 1995). Furthermore, these motifs are connected through N—H···O and C—H···O hydrogen bonds (Table 1), leading to a one-dimensional supramolecular chain along the c-axis. These chains are further connected via a pair of O—H···O hydrogen bonds involving centrosymmetric hydrogen fumarate anions, forming a two-dimensional network parallel to (010). These planes are further interconnected by O4–H1O4···O3 hydrogen bonds into a 3D network.
For applications of intermolecular interactions, see: Lam & Mak (2000). For related structures, see: Büyükgüngör & Odabąsoǧlu (2006); Hosomi et al. (2000); Smith et al. (2007); Cao et al. (2004); Natarajan et al. (2009). For hydrogen-bond motifs, see: Bernstein et al. (1995). For reference 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 asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level. Hydrogen atoms are shown as spheres of arbitrary radius. | |
Fig. 2. The crystal packing of the title compound, showing hydrogen-bonded (dashed lines) 2D networks parallel to (010). H atoms not involved in the intermolecular interactions have been omitted for clarity. |
C6H9N2+·C4H3O4− | F(000) = 472 |
Mr = 224.22 | Dx = 1.402 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 2803 reflections |
a = 5.0058 (16) Å | θ = 2.8–31.0° |
b = 19.814 (7) Å | µ = 0.11 mm−1 |
c = 11.286 (4) Å | T = 100 K |
β = 108.332 (13)° | Needle, colourless |
V = 1062.6 (6) Å3 | 0.36 × 0.10 × 0.07 mm |
Z = 4 |
Bruker APEXII DUO CCD area-detector diffractometer | 3387 independent reflections |
Radiation source: fine-focus sealed tube | 2573 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.041 |
φ and ω scans | θmax = 31.1°, θmin = 2.1° |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | h = −7→7 |
Tmin = 0.962, Tmax = 0.992 | k = −22→28 |
12900 measured reflections | l = −16→16 |
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)] = 0.046 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.168 | All H-atom parameters refined |
S = 1.07 | w = 1/[σ2(Fo2) + (0.106P)2 + 0.0446P] where P = (Fo2 + 2Fc2)/3 |
3387 reflections | (Δ/σ)max = 0.001 |
181 parameters | Δρmax = 0.51 e Å−3 |
0 restraints | Δρmin = −0.32 e Å−3 |
C6H9N2+·C4H3O4− | V = 1062.6 (6) Å3 |
Mr = 224.22 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 5.0058 (16) Å | µ = 0.11 mm−1 |
b = 19.814 (7) Å | T = 100 K |
c = 11.286 (4) Å | 0.36 × 0.10 × 0.07 mm |
β = 108.332 (13)° |
Bruker APEXII DUO CCD area-detector diffractometer | 3387 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2009) | 2573 reflections with I > 2σ(I) |
Tmin = 0.962, Tmax = 0.992 | Rint = 0.041 |
12900 measured reflections |
R[F2 > 2σ(F2)] = 0.046 | 0 restraints |
wR(F2) = 0.168 | All H-atom parameters refined |
S = 1.07 | Δρmax = 0.51 e Å−3 |
3387 reflections | Δρmin = −0.32 e Å−3 |
181 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 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. |
x | y | z | Uiso*/Ueq | ||
N1 | −0.1142 (2) | 0.80864 (6) | 0.55566 (10) | 0.0138 (2) | |
N2 | 0.0376 (2) | 0.76324 (6) | 0.75413 (11) | 0.0166 (2) | |
C1 | 0.0731 (3) | 0.80768 (7) | 0.67234 (11) | 0.0129 (3) | |
C2 | 0.2978 (3) | 0.85492 (7) | 0.70188 (12) | 0.0143 (3) | |
C3 | 0.3220 (3) | 0.90042 (7) | 0.61461 (12) | 0.0153 (3) | |
C4 | 0.1210 (3) | 0.89903 (7) | 0.49325 (12) | 0.0176 (3) | |
C5 | −0.0911 (3) | 0.85296 (7) | 0.46726 (12) | 0.0159 (3) | |
C6 | 0.5539 (3) | 0.95182 (8) | 0.64658 (13) | 0.0198 (3) | |
O1 | 0.4413 (2) | 0.77430 (5) | −0.00598 (9) | 0.0167 (2) | |
O2 | 0.5841 (2) | 0.82660 (5) | 0.17910 (9) | 0.0187 (2) | |
O3 | −0.33328 (19) | 0.94128 (5) | −0.04434 (9) | 0.0170 (2) | |
O4 | −0.2087 (2) | 0.98609 (5) | 0.14785 (9) | 0.0184 (2) | |
C7 | 0.4153 (3) | 0.81746 (7) | 0.07303 (11) | 0.0129 (3) | |
C8 | 0.1559 (3) | 0.86036 (7) | 0.03171 (12) | 0.0144 (3) | |
C9 | 0.0841 (3) | 0.90251 (7) | 0.10791 (12) | 0.0150 (3) | |
C10 | −0.1721 (3) | 0.94438 (7) | 0.06278 (12) | 0.0132 (3) | |
H1O4 | −0.368 (4) | 1.0119 (9) | 0.1114 (16) | 0.020* | |
H1N1 | −0.278 (4) | 0.7781 (9) | 0.5333 (16) | 0.016* | |
H1N2 | −0.124 (4) | 0.7315 (9) | 0.7264 (16) | 0.016* | |
H2N2 | 0.141 (4) | 0.7622 (9) | 0.8262 (17) | 0.016* | |
H2A | 0.428 (4) | 0.8529 (9) | 0.7855 (16) | 0.016* | |
H4A | 0.137 (4) | 0.9308 (9) | 0.4299 (16) | 0.016* | |
H5A | −0.244 (3) | 0.8495 (9) | 0.3834 (15) | 0.016* | |
H6A | 0.655 (4) | 0.9509 (10) | 0.5852 (16) | 0.020* | |
H6B | 0.683 (4) | 0.9461 (9) | 0.7285 (17) | 0.020* | |
H6C | 0.457 (4) | 0.9960 (10) | 0.6385 (16) | 0.020* | |
H8A | 0.029 (4) | 0.8563 (9) | −0.0593 (16) | 0.016* | |
H9A | 0.198 (4) | 0.9063 (9) | 0.1949 (16) | 0.016* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0130 (5) | 0.0153 (6) | 0.0118 (5) | −0.0028 (4) | 0.0020 (4) | −0.0010 (4) |
N2 | 0.0164 (5) | 0.0181 (6) | 0.0123 (5) | −0.0050 (4) | 0.0004 (4) | 0.0012 (4) |
C1 | 0.0126 (5) | 0.0137 (6) | 0.0119 (5) | −0.0010 (4) | 0.0031 (4) | −0.0015 (4) |
C2 | 0.0145 (5) | 0.0156 (6) | 0.0127 (5) | −0.0027 (4) | 0.0039 (4) | −0.0025 (5) |
C3 | 0.0161 (6) | 0.0164 (6) | 0.0146 (6) | −0.0032 (5) | 0.0064 (5) | −0.0024 (5) |
C4 | 0.0206 (6) | 0.0197 (7) | 0.0135 (6) | −0.0038 (5) | 0.0065 (5) | −0.0001 (5) |
C5 | 0.0167 (6) | 0.0184 (7) | 0.0115 (5) | −0.0012 (5) | 0.0029 (4) | −0.0011 (5) |
C6 | 0.0208 (6) | 0.0206 (7) | 0.0188 (6) | −0.0082 (5) | 0.0074 (5) | −0.0024 (5) |
O1 | 0.0160 (4) | 0.0174 (5) | 0.0143 (4) | 0.0045 (3) | 0.0013 (3) | −0.0027 (4) |
O2 | 0.0155 (4) | 0.0238 (6) | 0.0132 (4) | 0.0066 (4) | −0.0007 (3) | −0.0031 (4) |
O3 | 0.0152 (4) | 0.0195 (5) | 0.0144 (4) | 0.0052 (3) | 0.0019 (4) | −0.0021 (4) |
O4 | 0.0167 (5) | 0.0194 (5) | 0.0169 (5) | 0.0057 (4) | 0.0022 (4) | −0.0046 (4) |
C7 | 0.0121 (5) | 0.0129 (6) | 0.0131 (5) | 0.0014 (4) | 0.0033 (4) | 0.0014 (4) |
C8 | 0.0127 (5) | 0.0150 (6) | 0.0147 (6) | 0.0027 (4) | 0.0030 (4) | −0.0002 (5) |
C9 | 0.0131 (5) | 0.0166 (6) | 0.0141 (6) | 0.0028 (4) | 0.0023 (4) | −0.0003 (5) |
C10 | 0.0121 (5) | 0.0134 (6) | 0.0143 (6) | −0.0001 (4) | 0.0043 (4) | −0.0009 (4) |
N1—C1 | 1.3553 (16) | C6—H6A | 0.977 (18) |
N1—C5 | 1.3611 (17) | C6—H6B | 0.953 (19) |
N1—H1N1 | 0.987 (18) | C6—H6C | 0.991 (19) |
N2—C1 | 1.3276 (17) | O1—C7 | 1.2714 (15) |
N2—H1N2 | 0.994 (18) | O2—C7 | 1.2424 (16) |
N2—H2N2 | 0.816 (19) | O3—C10 | 1.2259 (16) |
C1—C2 | 1.4202 (18) | O4—C10 | 1.3224 (15) |
C2—C3 | 1.3683 (18) | O4—H1O4 | 0.93 (2) |
C2—H2A | 0.964 (17) | C7—C8 | 1.4987 (18) |
C3—C4 | 1.4219 (19) | C8—C9 | 1.3269 (18) |
C3—C6 | 1.5006 (19) | C8—H8A | 1.027 (17) |
C4—C5 | 1.3604 (19) | C9—C10 | 1.4769 (18) |
C4—H4A | 0.976 (17) | C9—H9A | 0.970 (18) |
C5—H5A | 1.015 (17) | ||
C1—N1—C5 | 121.94 (11) | N1—C5—H5A | 115.3 (10) |
C1—N1—H1N1 | 120.4 (10) | C3—C6—H6A | 110.5 (11) |
C5—N1—H1N1 | 117.6 (10) | C3—C6—H6B | 112.9 (11) |
C1—N2—H1N2 | 118.4 (10) | H6A—C6—H6B | 110.0 (16) |
C1—N2—H2N2 | 121.9 (13) | C3—C6—H6C | 105.0 (11) |
H1N2—N2—H2N2 | 119.7 (16) | H6A—C6—H6C | 107.3 (15) |
N2—C1—N1 | 118.80 (11) | H6B—C6—H6C | 110.9 (15) |
N2—C1—C2 | 122.92 (12) | C10—O4—H1O4 | 108.6 (11) |
N1—C1—C2 | 118.27 (11) | O2—C7—O1 | 125.82 (12) |
C3—C2—C1 | 120.53 (12) | O2—C7—C8 | 118.51 (11) |
C3—C2—H2A | 123.2 (11) | O1—C7—C8 | 115.67 (11) |
C1—C2—H2A | 116.3 (11) | C9—C8—C7 | 122.70 (12) |
C2—C3—C4 | 119.00 (12) | C9—C8—H8A | 119.2 (10) |
C2—C3—C6 | 120.72 (12) | C7—C8—H8A | 118.1 (10) |
C4—C3—C6 | 120.28 (12) | C8—C9—C10 | 120.85 (12) |
C5—C4—C3 | 119.24 (12) | C8—C9—H9A | 120.8 (11) |
C5—C4—H4A | 121.0 (10) | C10—C9—H9A | 118.3 (11) |
C3—C4—H4A | 119.7 (11) | O3—C10—O4 | 123.28 (12) |
C4—C5—N1 | 121.02 (12) | O3—C10—C9 | 122.87 (11) |
C4—C5—H5A | 123.7 (10) | O4—C10—C9 | 113.83 (11) |
C5—N1—C1—N2 | 179.79 (12) | C3—C4—C5—N1 | 0.3 (2) |
C5—N1—C1—C2 | 0.38 (18) | C1—N1—C5—C4 | −0.8 (2) |
N2—C1—C2—C3 | −178.88 (12) | O2—C7—C8—C9 | −7.3 (2) |
N1—C1—C2—C3 | 0.51 (19) | O1—C7—C8—C9 | 172.67 (13) |
C1—C2—C3—C4 | −1.0 (2) | C7—C8—C9—C10 | 179.34 (11) |
C1—C2—C3—C6 | 178.11 (12) | C8—C9—C10—O3 | 2.0 (2) |
C2—C3—C4—C5 | 0.5 (2) | C8—C9—C10—O4 | −177.01 (12) |
C6—C3—C4—C5 | −178.53 (13) |
D—H···A | D—H | H···A | D···A | D—H···A |
O4—H1O4···O3i | 0.928 (19) | 1.720 (19) | 2.6472 (17) | 179 (2) |
N1—H1N1···O1ii | 0.987 (18) | 1.689 (18) | 2.6761 (16) | 179.5 (17) |
N2—H1N2···O2ii | 0.994 (18) | 1.804 (18) | 2.7979 (16) | 179.0 (16) |
N2—H2N2···O1iii | 0.816 (19) | 2.028 (19) | 2.8320 (18) | 168.5 (18) |
C2—H2A···O3iv | 0.964 (18) | 2.596 (18) | 3.349 (2) | 135.1 (14) |
C5—H5A···O2v | 1.015 (16) | 2.239 (16) | 3.189 (2) | 155.0 (13) |
C6—H6B···O3iv | 0.954 (19) | 2.592 (19) | 3.360 (2) | 137.8 (16) |
Symmetry codes: (i) −x−1, −y+2, −z; (ii) x−1, −y+3/2, z+1/2; (iii) x, y, z+1; (iv) x+1, y, z+1; (v) x−1, y, z. |
Experimental details
Crystal data | |
Chemical formula | C6H9N2+·C4H3O4− |
Mr | 224.22 |
Crystal system, space group | Monoclinic, P21/c |
Temperature (K) | 100 |
a, b, c (Å) | 5.0058 (16), 19.814 (7), 11.286 (4) |
β (°) | 108.332 (13) |
V (Å3) | 1062.6 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.11 |
Crystal size (mm) | 0.36 × 0.10 × 0.07 |
Data collection | |
Diffractometer | Bruker APEXII DUO CCD area-detector diffractometer |
Absorption correction | Multi-scan (SADABS; Bruker, 2009) |
Tmin, Tmax | 0.962, 0.992 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 12900, 3387, 2573 |
Rint | 0.041 |
(sin θ/λ)max (Å−1) | 0.726 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.046, 0.168, 1.07 |
No. of reflections | 3387 |
No. of parameters | 181 |
H-atom treatment | All H-atom parameters refined |
Δρmax, Δρmin (e Å−3) | 0.51, −0.32 |
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 |
O4—H1O4···O3i | 0.928 (19) | 1.720 (19) | 2.6472 (17) | 179 (2) |
N1—H1N1···O1ii | 0.987 (18) | 1.689 (18) | 2.6761 (16) | 179.5 (17) |
N2—H1N2···O2ii | 0.994 (18) | 1.804 (18) | 2.7979 (16) | 179.0 (16) |
N2—H2N2···O1iii | 0.816 (19) | 2.028 (19) | 2.8320 (18) | 168.5 (18) |
C2—H2A···O3iv | 0.964 (18) | 2.596 (18) | 3.349 (2) | 135.1 (14) |
C5—H5A···O2v | 1.015 (16) | 2.239 (16) | 3.189 (2) | 155.0 (13) |
C6—H6B···O3iv | 0.954 (19) | 2.592 (19) | 3.360 (2) | 137.8 (16) |
Symmetry codes: (i) −x−1, −y+2, −z; (ii) x−1, −y+3/2, z+1/2; (iii) x, y, z+1; (iv) x+1, y, z+1; (v) x−1, y, z. |
Footnotes
‡Thomson Reuters ResearcherID: A-3561-2009.
Acknowledgements
MH and HKF thank the Malaysian Government and Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.
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Intermolecular interactions are responsible for crystal packing and gaining an understanding of them allows us to comprehend collective properties and permits the design of new crystals with specific physical and chemical properties (Lam & Mak, 2000). Fumaric acid, a key intermediate in organic acid biosynthesis, is known to readily form adducts/complexes with other organic molecules. The crystal structures of 2,6-diaminopyridinium hydrogen fumarate (Büyükgüngör & Odabąsoǧlu, 2006), triethylammonium hydrogen fumarate (Hosomi et al., 2000), anhydrous guanidinium hydrogen fumarate (Smith et al., 2007), tiamulin hydrogen fumarate methanol (Cao et al., 2004) and glycinium hydrogen fumarate glycine solvate monohydrate (Natarajan et al., 2009) have been reported. The present study has been undertaken to study the hydrogen bonding patterns involving the hydrogen fumarate anion with the 2-amino-4-methylpyridinium cation.
The asymmetric unit of the title compound consists of a 2-amino-4-methyl pyridinium cation and a hydrogen fumarate anion (Fig. 1). In the 2-amino- 4-methylpyridinium cation, a wider than normal angle [C1—N1—C5 121.94 (11)°] is subtended at the protonated N1 atom. The C10—O3 bond distance of 1.2259 (16) Å is much shorter than the C10—O4 bond distance of 1.3224 (15) Å, suggesting that the carboxyl group is not deprotonated in the crystal structure. The dihedral angle between the pyridine ring and the plane formed by the hydrogen fumarate anion is 85.67 (6)°. Excluding amino and methyl groups, the atoms of the cation are coplanar, with a maximum deviation of 0.005 (1) Å for atom C2. The bond lengths (Allen et al., 1987) and angles are normal.
In the crystal packing (Fig. 2), the protonated N1 atom and the 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O1 and O2) via a pair of N—H···O hydrogen bonds, forming a R22(8) ring motif (Bernstein et al., 1995). Furthermore, these motifs are connected through N—H···O and C—H···O hydrogen bonds (Table 1), leading to a one-dimensional supramolecular chain along the c-axis. These chains are further connected via a pair of O—H···O hydrogen bonds involving centrosymmetric hydrogen fumarate anions, forming a two-dimensional network parallel to (010). These planes are further interconnected by O4–H1O4···O3 hydrogen bonds into a 3D network.