2-Amino-5-methyl­pyridinium picolinate 0.63-hydrate

Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536810018180

. 2010 May 22;66(Pt 6):o1420–o1421. doi: 10.1107/S1600536810018180

2-Amino-5-methylpyridinium picolinate 0.63-hydrate

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

PMCID: PMC2979649 PMID: 21579497

Abstract

The asymmetric unit of the title compound, C₆H₉N₂ ⁺·C₆H₄NO₂ ⁻·0.63H₂O, contains two crystallographically independent 2-amino-5-methylpyridinium cations, a pair of picolinate anions and two water molecules, one with an occupancy of 0.25. Both the 2-amino-5-methylpyridine molecules are protonated at the pyridine N atoms. In the crystal structure, the cations, anions and water molecules are linked via N—H⋯O, N—H⋯N and O—H⋯O hydrogen bonds, as well as by C—H⋯O contacts, forming a chain along the b axis. In addition, weak π–π interactions are observed between pyridinium rings, with centroid–centroid distances of 3.5306 (13) Å.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997 ▶); Katritzky et al. (1996 ▶); Navarro Ranninger et al. (1985 ▶); Luque et al. (1997 ▶); Qin et al. (1999 ▶); Yip et al. (1999 ▶); Ren et al. (2002 ▶); Rivas et al. (2003 ▶); Jin et al. (2001 ▶); Albrecht et al. (2003 ▶); Nahringbauer & Kvick (1977 ▶). For details of hydrogen bonding, see: Jeffrey & Saenger (1991 ▶); Jeffrey (1997 ▶); Scheiner (1997 ▶). For details of picolinic acid, see: Mahler & Cordes (1971 ▶); Ogata et al. (2000 ▶). 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 ⁺·C₆H₄NO₂ ⁻·0.63H₂O
M _r = 242.51
Orthorhombic,
a = 12.126 (3) Å
b = 13.842 (3) Å
c = 14.318 (3) Å
V = 2403.4 (10) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.28 × 0.20 × 0.09 mm

Data collection

Bruker APEXII DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.973, T _max = 0.991
50363 measured reflections
3955 independent reflections
3119 reflections with I > 2σ(I)
R _int = 0.068

Refinement

R[F ² > 2σ(F ²)] = 0.046
wR(F ²) = 0.141
S = 1.09
3955 reflections
353 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.35 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/S1600536810018180/sj5005sup1.cif

e-66-o1420-sup1.cif^{(24.1KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810018180/sj5005Isup2.hkl

e-66-o1420-Isup2.hkl^{(190KB, 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
O2W—H2W2⋯O2Aⁱ	0.82	2.00	2.812 (2)	170
N1A—H1NA⋯O2Bⁱⁱ	0.99 (2)	1.69 (2)	2.669 (2)	170 (2)
N2A—H2NA⋯O1Bⁱⁱ	0.94 (3)	1.89 (3)	2.829 (2)	178 (3)
N2A—H3NA⋯N3A	0.94 (3)	2.08 (3)	3.019 (3)	177 (2)
N1B—H1NB⋯O2Aⁱ	0.96 (3)	1.68 (3)	2.642 (2)	173 (3)
N2B—H2NB⋯N3B	0.83 (3)	2.22 (3)	3.040 (2)	173 (2)
N2B—H3NB⋯O1Aⁱ	0.93 (2)	1.90 (2)	2.831 (3)	175 (2)
C5A—H5AA⋯O2Wⁱⁱⁱ	0.93	2.39	3.319 (3)	175
C7A—H7AA⋯O2B^iv	0.93	2.42	3.217 (3)	144
C8A—H8AA⋯O2W^v	0.93	2.50	3.339 (3)	151

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

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

Pyridine and its derivatives play an important role in heterocyclic chemistry (Pozharski et al., 1997; Katritzky et al., 1996). They are often involved in hydrogen-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). 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; Yip et al., 1999; Ren et al., 2002; Rivas et al., 2003) or as protonated cations (Luque et al., 1997; Jin et al., 2001; Albrecht et al., 2003). Picolinic acid (pyridine-2-carboxylic acid) is a well known terminal tryptophan metabolite (Mahler & Cordes, 1971). It induces apoptosis in leukaemia HL-60 cells (Ogata et al., 2000). Since our aim is to study some interesting hydrogen bonding interactions, the crystal structure of the title compound is presented here.

The asymmetric unit of the title compound consists of two crystallographically independent 2-amino-5-methylpyridinium cations (A and B), two picolinate anions (A and B) and two water molecules, O1W and O2W (with occupancies 0.25 and 1.0, respectively), (Fig. 1). Each 2-amino-5-methylpyridinium cation is planar, with a maximum deviation of 0.024 (2) Å for atom C6A in cation A and 0.005 (2) Å for atom C1B in cation B. In the cations, protonation at atoms N1A and N1B lead to a slight increase in the C1A—N1A—C5A [123.2 (2)°] and C1B—N1B—C5B [123.0 (2)°] angles compared to those observed in an unprotonated structure (Nahringbauer & Kvick, 1977). The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal structure (Fig. 2), the carboxylate groups of each picolinate anion interact with the corresponding 2-amino-5-methylpyridinium cations via a pair of N—H···O hydrogen bonds forming an R²₂(8) ring motif (Bernstein et al., 1995). The ionic units are linked by N—H···N, N—H···O, O—H···O and C—H···O (Table 1) hydrogen bonds, forming a one-dimensional chain along the b-axis. The crystal structure is further stabilized by π–π interactions involving the pyridinium (N1A/C1A–C5A) and pyridinium (N1B/C1B–C5B) rings, with centroid-to-centroid distance of 3.5306 (13) Å [symmetry code: 1-x, 1/2+y, 1/2-z].

Experimental

Hot methanol solutions (20 ml) of 2-amino-5-methylpyridine (54 mg, Aldrich) and picolinic acid (62 mg, Merck) were mixed and warmed over a a 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.