2-Amino-5-methyl­pyridinium 2-hydr­oxy-3,5-dinitro­benzoate

Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536810014480

. 2010 Apr 28;66(Pt 5):o1194–o1195. doi: 10.1107/S1600536810014480

2-Amino-5-methylpyridinium 2-hydroxy-3,5-dinitrobenzoate

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

PMCID: PMC2979276 PMID: 21579230

Abstract

In the title molecular salt, C₆H₉N₂ ⁺·C₇H₃N₂O₇ ⁻, the 2-amino-5-methylpyridinium cation is essentially planar, with a maximum deviation of 0.023 (1) Å. There is an intramolecular O—H⋯O hydrogen bond in the 3,5-dinitrosalicylate anion, which generates an S(6) ring motif. In the crystal, the protonated N atom and the 2-amino group are hydrogen bonded to the carboxylate O atoms via a pair of N—H⋯O hydrogen bonds, forming an R ₂ ²(8) ring motif. Weak intermolecular C—H⋯O interactions help to further stabilize the crystal structure.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997 ▶); Katritzky et al. (1996 ▶); Nahringbauer & Kvick (1977 ▶). For 3,5-dinitrosalicylic acid, see: Hindawey et al. (1980 ▶); Issa et al. (1981 ▶). 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 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₆H₉N₂ ⁺·C₇H₃N₂O₇ ⁻
M _r = 336.27
Triclinic,
a = 5.8673 (7) Å
b = 8.0991 (9) Å
c = 15.2437 (17) Å
α = 86.844 (3)°
β = 84.252 (3)°
γ = 81.209 (3)°
V = 711.69 (14) Å³
Z = 2
Mo Kα radiation
μ = 0.13 mm⁻¹
T = 100 K
0.29 × 0.14 × 0.08 mm

Data collection

Bruker APEX DUO CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.963, T _max = 0.990
12709 measured reflections
4947 independent reflections
3922 reflections with I > 2σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.045
wR(F ²) = 0.150
S = 1.08
4947 reflections
219 parameters
H-atom parameters constrained
Δρ_max = 0.51 e Å⁻³
Δρ_min = −0.46 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/S1600536810014480/hb5405sup1.cif

e-66-o1194-sup1.cif^{(18.8KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810014480/hb5405Isup2.hkl

e-66-o1194-Isup2.hkl^{(237.4KB, 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
O1—H1A⋯O7	0.82	1.66	2.4200 (13)	152
N1—H1⋯O6ⁱ	0.86	1.82	2.6768 (14)	174
N2—H2A⋯O7ⁱ	0.86	2.11	2.9668 (15)	176
N2—H2B⋯O1ⁱⁱ	0.86	2.16	2.8468 (15)	137
N2—H2B⋯O2ⁱⁱ	0.86	2.40	3.1723 (16)	149
C2—H2⋯O4ⁱⁱⁱ	0.93	2.49	3.4073 (16)	169
C4—H4⋯O3^iv	0.93	2.39	3.2371 (16)	151
C5—H5⋯O2ⁱⁱ	0.93	2.44	3.2328 (17)	143

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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

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). The nitro-substituted aromatic acid 3,5-dinitrosalicylic acid (DNSA) has proven potential for formation of proton-transfer compounds, particularly because of its acid strength (pKa = 2.18), its interactive ortho-related phenolic substituent group together with the nitro substituents which have potential for both π···π interactions as well as hydrogen-bonding interactions. A large number of both neutral and proton-transfer compounds of Lewis bases with DNSA, together with their IR spectra have been reported (Hindawey et al., 1980; Issa et al., 1981) in the literature. Since our aim is to study some interesting hydrogen bonding interactions, the crystal structure of the title compound is presented here.

The asymmetric unit (Fig. 1) contains one 2-amino-5-methylpyridinium cation and one 3,5-dinitrosalicylate anion. The proton transfer from the carboxyl group to atom N1 of 2-amino-5-methylpyridine resulted in the widening of C1—N1—C2 angle of the pyridinium ring to 123.48 (10)°, compared to the corresponding angle of 117.4° in neutral 2-amino-5-methylpyridine (Nahringbauer & Kvick, 1977). The 2-amino-5-methylpyridinium cation is essentially planar, with a maximum deviation of 0.023 (1) Å for atom N1. The bond lengths and angles are normal (Allen et al., 1987). The phenol oxygen atoms are bent slightly away from the mean plane of the benzene ring [torsion angle O1-C7-C8-C9 = 179.70 (12)°].

In the crystal packing (Fig. 2), the protonated N1 atom and the 2-amino group (N2) is hydrogen-bonded to the carboxylate oxygen atoms (O6 and O7) via a pair of intermolecular N1—H1···O6 and N2—H2A···O7 hydrogen bonds forming a ring motif R₂²(8) (Bernstein et al., 1995). There is an intramolecular O—H···O hydrogen bond in the 3,5-dinitrosalicylate anion, which generates an S(6) ring motif. The crystal structure is further stabilized by weak C—H···O (Table 1) hydrogen bonds.

Experimental

A hot methanol solution (20 ml) of 2-amino-5-methylpyridine (27 mg, Aldrich) and 3,5-dinitrosalicylic acid (58 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 yellow blocks of (I) appeared after a few days.