2-Amino-5-methyl­pyridinium 3-amino­benzoate

Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536810005180

. 2010 Feb 13;66(Pt 3):o623–o624. doi: 10.1107/S1600536810005180

2-Amino-5-methylpyridinium 3-aminobenzoate

Madhukar Hemamalini ^a, Hoong-Kun Fun ^a,^*,^‡

PMCID: PMC2983539 PMID: 21580381

Abstract

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 R ₂ ²(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 π⋯π stacking interactions involving the benzene and pyridinium rings with a centroid–centroid distance of 3.7594 (8) Å.

Related literature

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

Crystal data

C₆H₉N₂ ⁺·C₇H₆NO₂ ⁻
M _r = 245.28
Monoclinic,
a = 10.0739 (2) Å
b = 10.9620 (2) Å
c = 11.9641 (2) Å
β = 113.148 (1)°
V = 1214.83 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 296 K
0.72 × 0.34 × 0.13 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.936, T _max = 0.988
13305 measured reflections
3541 independent reflections
2576 reflections with I > 2σ(I)
R _int = 0.029

Refinement

R[F ² > 2σ(F ²)] = 0.048
wR(F ²) = 0.138
S = 1.07
3541 reflections
212 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.20 e Å⁻³
Δρ_min = −0.26 e Å⁻³

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

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810005180/lh2994sup1.cif

e-66-0o623-sup1.cif^{(17.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810005180/lh2994Isup2.hkl

e-66-0o623-Isup2.hkl^{(173.7KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
N1—H1N1⋯O2ⁱ	1.017 (17)	1.682 (17)	2.6901 (14)	170.6 (17)
N2—H1N2⋯O1ⁱ	0.939 (16)	1.886 (16)	2.8207 (15)	173.3 (14)
N2—H2N2⋯O2ⁱⁱ	0.920 (17)	1.947 (17)	2.8650 (16)	175.3 (16)
N3—H1N3⋯O1ⁱⁱⁱ	0.903 (19)	2.18 (2)	3.027 (2)	156.0 (17)

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

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.

supplementary crystallographic information

Comment

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 ].

Experimental

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.