2,3-Diamino­pyridinium 3-amino­benzoate

Kasthuri Balasubramani; Hoong-Kun Fun

doi:10.1107/S1600536809024362

. 2009 Jul 1;65(Pt 8):o1729–o1730. doi: 10.1107/S1600536809024362

2,3-Diaminopyridinium 3-aminobenzoate

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

PMCID: PMC2977358 PMID: 21583446

Abstract

In the title salt, C₅H₈N₃ ⁺·C₇H₆NO₂ ⁻, the pyridine N atom of the 2,3-diaminopyridine molecule is protonated. The protonated N atom and one of the two N atoms of the 2-amino groups are hydrogen bonded to the 3-aminobenzoate anion through a pair of N—H⋯O hydrogen bonds, forming an R ₂ ²(8) ring motif. The carboxylate mean plane of the 3-aminobenzoate anion is twisted by 8.81 (7)° from the attached ring. The crystal structure is further stabilized by π–π interactions [centroid–centroid distance 3.6827 (7) Å].

Related literature

For substituted pyridines, see: Pozharski et al. (1997 ▶); Katritzky et al. (1996 ▶). For hydrogen bonding in pyridine and its substituted derivatives, see: Jeffrey & Saenger (1991 ▶); Jeffrey (1997 ▶); Scheiner (1997 ▶). For related structures, see: Fun & Balasubramani (2009 ▶); Balasubramani & Fun (2009a ▶,b ▶). For bond-length data, see: Allen et al. (1987 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₅H₈N₃ ⁺·C₇H₆NO₂ ⁻
M _r = 246.27
Monoclinic,
a = 9.9119 (2) Å
b = 10.1751 (2) Å
c = 12.4060 (2) Å
β = 106.811 (1)°
V = 1197.73 (4) Å³
Z = 4
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 K
0.46 × 0.14 × 0.06 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2005 ▶) T _min = 0.957, T _max = 0.994
19514 measured reflections
4434 independent reflections
2965 reflections with I > 2σ(I)
R _int = 0.046

Refinement

R[F ² > 2σ(F ²)] = 0.050
wR(F ²) = 0.142
S = 1.06
4434 reflections
219 parameters
All H-atom parameters refined
Δρ_max = 0.33 e Å⁻³
Δρ_min = −0.23 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/S1600536809024362/bt2977sup1.cif

e-65-o1729-sup1.cif^{(17.5KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809024362/bt2977Isup2.hkl

e-65-o1729-Isup2.hkl^{(212.9KB, 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
N2—H2N2⋯O2ⁱ	0.91 (2)	2.02 (2)	2.9293 (14)	177.1 (17)
N3—H1N3⋯O2ⁱ	0.92 (2)	2.08 (2)	2.9854 (16)	167.3 (18)
N3—H2N3⋯O1ⁱⁱ	0.96 (2)	2.04 (2)	2.9544 (14)	158.1 (16)
N4—H1N4⋯O1ⁱⁱⁱ	0.95 (2)	2.06 (2)	2.9794 (15)	162.3 (18)
N1—H1N1⋯O2	0.99 (2)	1.77 (2)	2.7510 (13)	167.1 (15)
N2—H1N2⋯O1	0.94 (2)	1.87 (2)	2.8086 (14)	175.7 (16)

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

Acknowledgments

KBS and HKF thank the Malaysian Government and Universiti Sains Malaysia for the Science Fund grant No. 305/PFIZIK/613312. KBS 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). The crystal structures of 2,3-diaminopyridinium 4-hydroxybenzoate (Fun & Balasubramani, 2009), 2,3-diaminopyridinium 4-nitrobenzoate (Balasubramani & Fun, 2009a) and 2,3-diaminopyridinium benzoate (Balasubramani & Fun, 2009b) have been reported by us recently. In the hope to study some interesting hydrogen-bonding interactions, the title compound (I) was synthesized. Its molecular and crystal structure is presented here.

The asymmetric unit of (I) (Fig 1), contains a protonated 2,3-diaminopyridinium cation and an 3-aminobenzoate anion. The bond lengths (Allen et al., 1987) and angles are normal. In the 2,3-diaminopyridinium cation, the protonated N1 atom has lead to a slight increase in the C8—N1—C12 angle to 123.37 (11)°. The carboxylate group is twisted slightly from the ring with the dihedral angle between C1—C6 and O1/O2/C7/C6 planes being 8.81 (7)°. The 2,3-diaminopyridinium cation is planar, with a maximum deviation of 0.0126 (14) Å for atom C9.

In the crystal packing (Fig. 2), the protonated N1 atom and a nitrogen atom of the 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O2 and O1) via a pair of N—H···O hydrogen bonds forming a ring motif R₂²(8) (Bernstein et al., 1995). The 2-amino groups (N2 and N3) are involved in N—H···O hydrogen bonding interactions to form a R¹₂(7) ring motif. The symmetry-related 3-aminobenzoate molecules are linked through N—H···O hydrogen-bonding to form a R²₂(14) ring motif (Table 1 and Fig. 2). The cystal structure is further stabilized by a π-π stacking interaction between the aminopyridine rings (C8—C12/N1) with centroid-to-centroid distance of 3.6827 (7) Å, perpendicular interplanar distance of 3.3536 (5) Å.

Experimental

Hot methanol solutions (20 ml) of 2,3-diaminopyridine (27 mg, Aldrich) and 3-aminobenzoic 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 (I) appeared from the mother liquor after a few days.