2,3-Diamino­pyridinium 4-hydroxy­benzoate

Hoong-Kun Fun; Kasthuri Balasubramani

doi:10.1107/S1600536809020832

. 2009 Jun 6;65(Pt 7):o1496–o1497. doi: 10.1107/S1600536809020832

2,3-Diaminopyridinium 4-hydroxybenzoate

Hoong-Kun Fun ^a,^*,^‡, Kasthuri Balasubramani ^a

PMCID: PMC2969455 PMID: 21582796

Abstract

In the title compound, C₅H₈N₃ ⁺·C₇H₅O₃ ⁻, the pyridine N atom is protonated. In the 4-hydroxybenzoate anion, the carboxylate group is twisted slightly out of the benzene ring plane by an angle of 3.77 (5)°. The protonated N atom and one of the two amino groups are hydrogen-bonded to the 4-hydroxybenzoate anion through a pair of N—H⋯O hydrogen bonds, forming an R ₂ ²(8) ring motif. The crystal structure is further stabilized by O—H⋯O and C—H⋯O hydrogen bonds and π–π interactions involving the pyridinium rings [centroid–centroid distance of 3.6277 (5) Å], leading to the formation of a three-dimensional network.

Related literature

For general background to substituted pyridines, see: Pozharski et al. (1997 ▶); Katritzky et al. (1996 ▶). 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

C₅H₈N₃ ⁺·C₇H₅O₃ ⁻
M _r = 247.25
Monoclinic,
a = 10.2915 (2) Å
b = 11.4946 (2) Å
c = 11.0921 (2) Å
β = 112.644 (1)°
V = 1211.01 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.51 × 0.39 × 0.14 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.950, T _max = 0.986
25821 measured reflections
5296 independent reflections
4257 reflections with I > 2σ(I)
R _int = 0.034

Refinement

R[F ² > 2σ(F ²)] = 0.049
wR(F ²) = 0.138
S = 1.04
5296 reflections
215 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.65 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Data collection: APEX2 (Bruker, 2005 ▶); cell refinement: SAINT (Bruker, 2005 ▶); 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/S1600536809020832/ci2813sup1.cif

e-65-o1496-sup1.cif^{(17.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809020832/ci2813Isup2.hkl

e-65-o1496-Isup2.hkl^{(254.1KB, 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⋯O2	0.89 (2)	1.903 (15)	2.7874 (9)	173 (1)
N2—H2N2⋯O3	0.89 (1)	1.898 (14)	2.7843 (9)	176 (1)
N2—H1N2⋯O2ⁱ	0.87 (1)	2.014 (15)	2.8689 (9)	168 (1)
N3—H1N3⋯O2ⁱ	0.91 (2)	2.071 (16)	2.9790 (10)	174 (1)
N3—H2N3⋯O3ⁱⁱ	0.89 (2)	2.057 (15)	2.9285 (10)	166 (1)
O1—H1O1⋯O3ⁱⁱⁱ	0.90 (2)	1.775 (19)	2.6595 (8)	168 (2)
C2—H2⋯O3ⁱⁱⁱ	1.00 (1)	2.500 (14)	3.2104 (10)	128 (1)

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

Acknowledgments

HKF and KB thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. KB thanks Universiti Sains Malaysia for a post–doctoral research fellowship. HKF also thanks Universiti Sains Malaysia for the Research University Golden Goose grant No. 1001/PFIZIK/811012.

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). 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 (Fig 1), contains one 2,3-diaminopyridinium cation and one 4-hydroxybenzoate anion. The bond lengths (Allen et al., 1987) and angles are normal. The 2,3-diaminopyridinium cation is planar to within ±0.015 (1) Å. The protonation of N1 atom resulted in a slight increase in the C8—N1—C12 angle [123.47 (7)°]. In the anion, the carboxylate group is twisted slightly away from the attached ring; the dihedral angle between C1-C6 and O2/O3/C7/C6 planes is 3.77 (5)°.

In the crystal packing (Fig. 2), the protonated N1 atom and the 2-amino group (N2) is hydrogen-bonded to the carboxylate oxygen atoms (O2 and O3) via a pair of N—H···O hydrogen bonds forming a ring motif R₂²(8) (Bernstein et al., 1995). The amino groups (N2 and N3) are involved in N—H···O hydrogen bonding interactions to form a R¹₂(7) ring motif. The hydroxyl group hydrogen atom is also hydrogen-bonded to the carboxylate oxygen atom through O—H···O hydrogen bonds. Moreover O—H···O and C—H···O hydrogen bonds form a R¹₂(6) ring motif (Table 1 and Fig 2). The crystal structure is further stabilized by π-π stacking interactions between the pyridinium rings (C8—C12/N1) at (x, y, z) and (2-x, 2-y, 1-z), with a centroid-to-centroid distance of 3.6277 (5) Å.

Experimental

Hot methanol solutions (20 ml) of 2,3-diaminopyridine (27 mg, Aldrich) and 4-hydroxybenzoic acid (35 mg, Merck) were mixed and warmed over a heating magnetic stirrer for 5 minutes. The resulting solution was allowed to cool slowly at room temperature. Crystals of the title compound appeared from the mother liquor after a few days.