2-Amino-4-methyl­pyridinium 2-hy­droxy­benzoate

Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S160053681002965X

. 2010 Jul 31;66(Pt 8):o2151–o2152. doi: 10.1107/S160053681002965X

2-Amino-4-methylpyridinium 2-hydroxybenzoate

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

PMCID: PMC3007449 PMID: 21588437

Abstract

The asymmetric unit of the title molecular salt, C₆H₉N₂ ⁺·C₇H₅O₃ ⁻, contains two cations and two anions. Both the salicylate anions contain an intramolecular O—H⋯O hydrogen bond, which generates an S(6) ring. Both the 2-amino-4-methylpyridine molecules are protonated at their pyridine N atoms. In the crystal, both cations form two N—H⋯O hydrogen bonds to their adjacent anions, forming ion pairs. Further N—H⋯O links generate sheets lying parallel to the ab plane. In addition, weak C—H⋯O bonds and aromatic π–π stacking interactions [centroid–centroid distances = 3.5691 (9) and 3.6215 (9) Å] are observed between the cations and anions.

Related literature

For related structures, see: Navarro Ranninger et al. (1985 ▶); Luque et al. (1997 ▶); Qin et al. (1999 ▶); Jin et al. (2001); Albrecht et al. (2003 ▶); 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

C₆H₉N₂ ⁺·C₇H₅O₃ ⁻
M _r = 246.26
Triclinic,
a = 7.2417 (2) Å
b = 12.5520 (3) Å
c = 14.7699 (3) Å
α = 68.752 (2)°
β = 82.038 (2)°
γ = 88.824 (2)°
V = 1238.58 (5) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.32 × 0.10 × 0.04 mm

Data collection

Bruker APEXII CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.971, T _max = 0.996
23090 measured reflections
8280 independent reflections
5112 reflections with I > 2σ(I)
R _int = 0.047

Refinement

R[F ² > 2σ(F ²)] = 0.056
wR(F ²) = 0.155
S = 1.00
8280 reflections
359 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.38 e Å⁻³
Δρ_min = −0.28 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/S160053681002965X/hb5564sup1.cif

e-66-o2151-sup1.cif^{(24.4KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S160053681002965X/hb5564Isup2.hkl

e-66-o2151-Isup2.hkl^{(396.9KB, 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
O3A—H1A3⋯O2A	0.99 (2)	1.61 (2)	2.5310 (16)	154 (2)
N1A—H1NA⋯O1Bⁱ	0.99 (2)	1.71 (2)	2.6965 (17)	174 (2)
N2A—H2NA⋯O1Aⁱⁱ	0.90 (2)	1.99 (2)	2.8645 (19)	164 (2)
O3B—H1B3⋯O2B	0.94 (3)	1.62 (3)	2.5179 (16)	158 (2)
N2A—H3NA⋯O2Bⁱ	0.94 (2)	1.91 (2)	2.8468 (18)	178 (2)
N1B—H1NB⋯O2A	0.96 (2)	1.76 (2)	2.7186 (17)	172.7 (17)
N2B—H2NB⋯O1A	0.96 (2)	1.84 (2)	2.7976 (18)	177.0 (16)
N2B—H3NB⋯O1Bⁱⁱⁱ	0.93 (2)	1.88 (2)	2.8097 (19)	174.3 (13)
C8B—H8BA⋯O2B^iv	0.93	2.47	3.357 (2)	159
C10B—H10B⋯O3B	0.93	2.38	3.039 (2)	128

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

Acknowledgments

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.

supplementary crystallographic information

Comment

There are numerous examples of 2-amino-substituted pyridine compounds in which the 2-aminopyridines act as neutral ligands (Navarro Ranninger et al., 1985; Luque et al., 1997; Qin et al., 1999) or as protonated cations (Luque et al., 1997; Jin et al., 2001; Albrecht et al., 2003). In order to study some hydrogen bonding interactions, the synthesis and structure of the title salt, (I), is presented here.

The asymmetric unit of the title compound consists of two crystallographically independent 2-amino-4-methylpyridinium cations (A and B) and two salicylate anions (A and B) (Fig. 1). Each 2-amino-4-methylpyridinium cation is planar, with a maximum deviation of 0.004 (1) Å for atom N1A in cation A and 0.006 (2) Å for atom C11B in cation B. In the cations, protonation at atoms N1A and N1B lead to a slight increase in the C9A—N1A—C10A [122.06 (14)°] and C9B—N1B—C10B [121.76 (13)°] angles compared to those observed in an unprotonated structure (Kvick & Noordik, 1977). The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal structure (Fig. 2), the carboxylate groups of each salicylate anions interact with the corresponding 2-amino-4-methylpyridinium cations via a pair of N—H···O hydrogen bonds forming an R₂²(8) ring motif (Bernstein et al., 1995). Furthermore, these motifs are connected via N—H···O hydrogen bonds, forming a two-dimensional network parallel to the ab-plane. There is an intramolecular O—H···O hydrogen bond in the salicylate anions, which generates an S(6) ring motif. In addition, weak C—H···O and π–π interactions are observed between the cation-anion pairs, [Cg1(N1A/C8A–C12A)& Cg4(C1A–C6A)] and [Cg2(N1B/C8B–C12B) & Cg3(C1B–C6B)], with centroid-centroid distances of 3.5691 (9) Å (1+x, y, z) and 3.6215 (9) Å (-1+x, y, z), respectively.

Experimental

A hot methanol solution (20 ml) of 2-amino-4-methylpyridine (54 mg, Aldrich) and salicylic acid (69 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 colourless needles of (I) appeared after a few days.