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Acta Cryst. (2010). E66, o623-o624    [ doi:10.1107/S1600536810005180 ]

2-Amino-5-methylpyridinium 3-aminobenzoate

M. Hemamalini and H.-K. Fun

Abstract top

In the title compound, C6H9N2+·C7H6NO2-, the H atom of the N-H group and an H atom of the 2-amino group from the cation are involved in intermolecular N-H...O hydrogen bonds with the O atoms of the carboxylate group of the anion, forming an R22(8) ring motif. These ring motifs are, in turn, connected by further N-H...O hydrogen bonds, forming a two-dimensional network. The crystal structure is further stabilized by [pi]...[pi] stacking interactions involving the benzene and pyridinium rings with a centroid-centroid distance of 3.7594 (8) Å.

Comment top

Pyridine and its derivatives play an important role in heterocyclic chemistry (Pozharski et al., 1997; Katritzky et al., 1996). Pyridine and its substituted derivatives are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). The crystal structures of 2-amino-5-methylpyridine (Nahringbauer & Kvick, 1977), 2-amino-5-methylpyridinium phosphate (Feng et al., 2005), 2-amino-5-methylpyridinium 3-(4- hydroxy-3-methoxyphenyl)-2-propenoate monohydrate (Xuan et al., 2003) and 2-amino-5-methylpyridinium (2-amino-5-methylpyridine)trichlorozincate(II) (Jin et al., 2005) have been reported in the literature. In order to study some interesting hydrogen bonding interactions, the synthesis and structure of the title salt is presented here.

The asymmetric unit (Fig. 1) contains a 2-amino-5-methylpyridinium cation and a 3-aminobenzoate anion. The proton transfer from the carboxyl group to atom N1 of 2-amino-5-methylpyridine resulted in the widening of C2—N1—C1 angle of the pyridinium ring to 122.40 (10)°, compared to the corresponding angle of 117.4° (no standard uncertainty available) in neutral 2-amino-5-methylpyridine (Nahringbauer & Kvick, 1977). The 2-amino-5-methylpyridinium cation is essentially planar, with a maximum deviation of 0.002 (1)Å for atom N1. The bond lengths (Allen et al., 1987) and angles are within normal ranges.

In the crystal structure (Fig. 2), the protonated N1 atom and 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 ring motif R22(8) (Bernstein et al., 1995). The symmetry-related 3-aminobenzoate molecules are linked through N3—H1N3···O1(-x+1, -y+1, -z+2) hydrogen-bonding to form a R22(14) ring motif (Table 1). The cystal structure is further stabilized by π···π stacking interaction between the pyridine rings (C1–C5/N1) and benzene ring (C7–C12) with centroid- to-centroid distance of 3.7594 (8)Å [symmetry codes: 1-x, 1/2+y, 3/2-z and 1-x, -1/2+y, 3/2-z ].

Related literature top

For background to the chemistry of substituted pyridines see: Pozharski et al. (1997); Katritzky et al. (1996). For related structures, see: Nahringbauer & Kvick (1977); Feng et al. (2005); Xuan et al. (2003); Jin et al. (2005). For details of hydrogen bonding, see: Jeffrey & Saenger (1991); Jeffrey (1997); Scheiner (1997). For hydrogen-bond motifs, see: Bernstein et al. (1995). For bond-length data, see: Allen et al. (1987).

Experimental top

A hot methanol solution (20 ml) of 2-amino-5-methylpyridine (54 mg, Aldrich) and 3-aminobenzoic acid (68 mg, Merck) were mixed and warmed over a heating magnetic stirrer 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.

Refinement top

The methyl H atoms were positioned geometrically and were refined using a riding model, with Uiso(H) = 1.5Ueq(C). A rotating group model was used for the methyl group. The remaining H atoms were located in a difference map and refined freely [N–H = 0.92 (2)–1.02 (2)Å, C–H = 0.96–1.00 (2)Å].

Computing details top

Data collection: APEX2 (Bruker, 2009); cell refinement: 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).

Figures top
[Figure 1] Fig. 1. The asymmetric unit of the title compound. Displacement ellipsoids are drawn at the 50% probability level.
[Figure 2] Fig. 2. The crystal packing of the title compound, showing hydrogen-bonded (dashed lines) networks.
2-amino-5-methylpyridinium 3-aminobenzoate top
Crystal data top
C6H9N2+·C7H6NO2−F(000) = 520
Mr = 245.28Dx = 1.341 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3778 reflections
a = 10.0739 (2) Åθ = 2.6–29.9°
b = 10.9620 (2) ŵ = 0.09 mm−1
c = 11.9641 (2) ÅT = 296 K
β = 113.148 (1)°Plate, brown
V = 1214.83 (4) Å30.72 × 0.34 × 0.13 mm
Z = 4
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		3541 independent reflections
Radiation source: fine-focus sealed tube2576 reflections with I > 2σ(I)
graphiteRint = 0.029
φ and ω scansθmax = 30.1°, θmin = 2.2°
Absorption correction: multi-scan
(SADABS; Bruker, 2009)		h = −10→14
Tmin = 0.936, Tmax = 0.988k = −15→13
13305 measured reflectionsl = −16→16
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.048Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.138H atoms treated by a mixture of independent and constrained refinement
S = 1.07 w = 1/[σ2(Fo2) + (0.0676P)2 + 0.1203P]
where P = (Fo2 + 2Fc2)/3
3541 reflections(Δ/σ)max = 0.001
212 parametersΔρmax = 0.20 e Å−3
0 restraintsΔρmin = −0.26 e Å−3
Crystal data top
C6H9N2+·C7H6NO2−V = 1214.83 (4) Å3
Mr = 245.28Z = 4
Monoclinic, P21/cMo Kα radiation
a = 10.0739 (2) ŵ = 0.09 mm−1
b = 10.9620 (2) ÅT = 296 K
c = 11.9641 (2) Å0.72 × 0.34 × 0.13 mm
β = 113.148 (1)°
Data collection top
Bruker SMART APEXII CCD area-detector
diffractometer		3541 independent reflections
Absorption correction: multi-scan
(SADABS; Bruker, 2009)		2576 reflections with I > 2σ(I)
Tmin = 0.936, Tmax = 0.988Rint = 0.029
13305 measured reflectionsθmax = 30.1°
Refinement top
R[F2 > 2σ(F2)] = 0.048H atoms treated by a mixture of independent and constrained refinement
wR(F2) = 0.138Δρmax = 0.20 e Å−3
S = 1.07Δρmin = −0.26 e Å−3
3541 reflectionsAbsolute structure: ?
212 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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) top
xyzUiso*/Ueq
N10.03024 (11)0.31395 (9)0.56765 (8)0.0363 (2)
N2−0.07229 (13)0.27732 (11)0.70650 (10)0.0477 (3)
C10.12267 (13)0.37351 (11)0.52889 (10)0.0377 (3)
C20.01813 (13)0.34187 (11)0.67327 (10)0.0364 (3)
C30.10505 (14)0.43720 (12)0.74341 (10)0.0418 (3)
C40.19709 (14)0.49686 (12)0.70412 (11)0.0430 (3)
C50.20896 (13)0.46594 (11)0.59348 (10)0.0390 (3)
C60.31252 (16)0.53099 (14)0.55236 (13)0.0546 (4)
H6A0.29790.50450.47190.082*
H6B0.40970.51280.60690.082*
H6C0.29640.61730.55190.082*
O10.74312 (11)0.37847 (9)1.02381 (8)0.0506 (3)
O20.87300 (12)0.35863 (9)0.91200 (8)0.0552 (3)
N30.44474 (16)0.75758 (13)0.87306 (15)0.0620 (4)
C70.61001 (13)0.58920 (11)0.90248 (10)0.0380 (3)
C80.54279 (13)0.69494 (11)0.84017 (11)0.0396 (3)
C90.57809 (14)0.73551 (12)0.74452 (11)0.0415 (3)
C100.67681 (15)0.67294 (12)0.71301 (11)0.0424 (3)
C110.74400 (14)0.56839 (12)0.77538 (10)0.0392 (3)
C120.70967 (12)0.52632 (10)0.87065 (9)0.0343 (3)
C130.78005 (13)0.41271 (11)0.94066 (9)0.0371 (3)
H10.1227 (15)0.3450 (13)0.4509 (14)0.049 (4)*
H30.0993 (15)0.4581 (13)0.8200 (13)0.048 (4)*
H40.2602 (17)0.5628 (15)0.7561 (14)0.061 (4)*
H70.5865 (15)0.5593 (13)0.9703 (13)0.046 (4)*
H90.5270 (16)0.8131 (14)0.6969 (14)0.056 (4)*
H100.7025 (16)0.7023 (13)0.6453 (14)0.053 (4)*
H110.8116 (16)0.5214 (14)0.7520 (13)0.050 (4)*
H1N1−0.0365 (17)0.2494 (16)0.5130 (15)0.062 (5)*
H1N2−0.1357 (17)0.2226 (15)0.6504 (14)0.056 (4)*
H2N2−0.0953 (16)0.3031 (14)0.7699 (15)0.055 (4)*
H1N30.4107 (18)0.7223 (17)0.9247 (17)0.067 (5)*
H2N30.395 (2)0.8179 (18)0.8245 (18)0.077 (6)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0421 (5)0.0357 (5)0.0327 (4)−0.0030 (4)0.0163 (4)−0.0047 (4)
N20.0578 (7)0.0513 (7)0.0429 (5)−0.0101 (6)0.0294 (5)−0.0079 (5)
C10.0405 (6)0.0398 (6)0.0341 (5)−0.0004 (5)0.0162 (5)−0.0022 (4)
C20.0412 (6)0.0359 (6)0.0336 (5)0.0034 (5)0.0163 (4)−0.0009 (4)
C30.0457 (7)0.0433 (7)0.0359 (5)0.0016 (6)0.0156 (5)−0.0092 (5)
C40.0420 (7)0.0386 (6)0.0448 (6)−0.0020 (5)0.0132 (5)−0.0103 (5)
C50.0372 (6)0.0371 (6)0.0421 (6)0.0004 (5)0.0148 (5)−0.0003 (5)
C60.0516 (8)0.0563 (9)0.0584 (8)−0.0131 (7)0.0242 (6)−0.0058 (6)
O10.0655 (6)0.0505 (6)0.0456 (5)0.0114 (5)0.0323 (4)0.0126 (4)
O20.0757 (7)0.0558 (6)0.0455 (5)0.0294 (5)0.0362 (5)0.0148 (4)
N30.0660 (9)0.0531 (8)0.0837 (9)0.0201 (7)0.0475 (8)0.0152 (7)
C70.0419 (6)0.0377 (6)0.0380 (5)0.0000 (5)0.0197 (5)0.0003 (5)
C80.0363 (6)0.0370 (6)0.0461 (6)−0.0003 (5)0.0169 (5)−0.0025 (5)
C90.0404 (7)0.0366 (6)0.0441 (6)0.0001 (5)0.0130 (5)0.0053 (5)
C100.0463 (7)0.0442 (7)0.0387 (5)−0.0021 (6)0.0187 (5)0.0062 (5)
C110.0426 (7)0.0414 (7)0.0376 (5)0.0025 (5)0.0200 (5)0.0007 (5)
C120.0378 (6)0.0339 (6)0.0308 (5)−0.0006 (5)0.0130 (4)−0.0014 (4)
C130.0465 (7)0.0354 (6)0.0300 (5)0.0033 (5)0.0156 (4)−0.0008 (4)
Geometric parameters (Å, °) top
N1—C21.3515 (14)O1—C131.2490 (14)
N1—C11.3593 (16)O2—C131.2642 (15)
N1—H1N11.018 (17)N3—C81.3811 (18)
N2—C21.3316 (16)N3—H1N30.904 (19)
N2—H1N20.938 (17)N3—H2N30.89 (2)
N2—H2N20.921 (17)C7—C121.3888 (17)
C1—C51.3607 (17)C7—C81.4003 (17)
C1—H10.984 (15)C7—H70.986 (15)
C2—C31.4090 (17)C8—C91.3977 (18)
C3—C41.3605 (19)C9—C101.3771 (19)
C3—H30.968 (14)C9—H91.040 (16)
C4—C51.4163 (17)C10—C111.3897 (18)
C4—H41.001 (16)C10—H100.995 (15)
C5—C61.4974 (19)C11—C121.3933 (16)
C6—H6A0.9600C11—H110.978 (15)
C6—H6B0.9600C12—C131.5126 (16)
C6—H6C0.9600
C2—N1—C1122.40 (10)H6B—C6—H6C109.5
C2—N1—H1N1118.6 (9)C8—N3—H1N3119.2 (11)
C1—N1—H1N1118.9 (9)C8—N3—H2N3117.7 (13)
C2—N2—H1N2118.7 (10)H1N3—N3—H2N3119.6 (17)
C2—N2—H2N2120.4 (10)C12—C7—C8121.01 (11)
H1N2—N2—H2N2117.6 (13)C12—C7—H7119.6 (8)
N1—C1—C5122.30 (11)C8—C7—H7119.4 (8)
N1—C1—H1115.2 (8)N3—C8—C9121.04 (12)
C5—C1—H1122.5 (8)N3—C8—C7120.67 (12)
N2—C2—N1118.85 (11)C9—C8—C7118.28 (12)
N2—C2—C3123.65 (11)C10—C9—C8120.61 (11)
N1—C2—C3117.48 (11)C10—C9—H9120.8 (9)
C4—C3—C2119.94 (11)C8—C9—H9118.6 (9)
C4—C3—H3121.1 (8)C9—C10—C11121.03 (12)
C2—C3—H3119.0 (8)C9—C10—H10120.6 (9)
C3—C4—C5121.83 (11)C11—C10—H10118.4 (9)
C3—C4—H4119.0 (9)C10—C11—C12119.16 (12)
C5—C4—H4119.1 (9)C10—C11—H11121.8 (8)
C1—C5—C4116.05 (12)C12—C11—H11119.0 (8)
C1—C5—C6122.69 (11)C7—C12—C11119.91 (11)
C4—C5—C6121.25 (11)C7—C12—C13119.26 (10)
C5—C6—H6A109.5C11—C12—C13120.83 (11)
C5—C6—H6B109.5O1—C13—O2124.01 (11)
H6A—C6—H6B109.5O1—C13—C12117.84 (11)
C5—C6—H6C109.5O2—C13—C12118.15 (10)
H6A—C6—H6C109.5
C2—N1—C1—C5−0.37 (18)N3—C8—C9—C10179.50 (12)
C1—N1—C2—N2−178.35 (11)C7—C8—C9—C10−0.18 (18)
C1—N1—C2—C30.48 (17)C8—C9—C10—C11−0.16 (19)
N2—C2—C3—C4178.51 (12)C9—C10—C11—C120.43 (19)
N1—C2—C3—C4−0.26 (18)C8—C7—C12—C110.00 (18)
C2—C3—C4—C5−0.1 (2)C8—C7—C12—C13179.81 (10)
N1—C1—C5—C40.01 (18)C10—C11—C12—C7−0.35 (18)
N1—C1—C5—C6179.17 (12)C10—C11—C12—C13179.84 (11)
C3—C4—C5—C10.20 (19)C7—C12—C13—O11.32 (17)
C3—C4—C5—C6−178.97 (12)C11—C12—C13—O1−178.87 (11)
C12—C7—C8—N3−179.42 (12)C7—C12—C13—O2−178.33 (10)
C12—C7—C8—C90.26 (18)C11—C12—C13—O21.48 (17)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1N1···O2i1.017 (17)1.682 (17)2.6901 (14)170.6 (17)
N2—H1N2···O1i0.939 (16)1.886 (16)2.8207 (15)173.3 (14)
N2—H2N2···O2ii0.920 (17)1.947 (17)2.8650 (16)175.3 (16)
N3—H1N3···O1iii0.903 (19)2.18 (2)3.027 (2)156.0 (17)
Symmetry codes: (i) x−1, −y+1/2, z−1/2; (ii) x−1, y, z; (iii) −x+1, −y+1, −z+2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
N1—H1N1···O2i1.017 (17)1.682 (17)2.6901 (14)170.6 (17)
N2—H1N2···O1i0.939 (16)1.886 (16)2.8207 (15)173.3 (14)
N2—H2N2···O2ii0.920 (17)1.947 (17)2.8650 (16)175.3 (16)
N3—H1N3···O1iii0.903 (19)2.18 (2)3.027 (2)156.0 (17)
Symmetry codes: (i) x−1, −y+1/2, z−1/2; (ii) x−1, y, z; (iii) −x+1, −y+1, −z+2.
Acknowledgements top

MH and HKF thank the Malaysian Government and Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012. MH thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

references
References top

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