2-Amino-5-bromo­pyridinium 3-carb­oxy­prop-2-enoate

Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536810030059

. 2010 Aug 4;66(Pt 9):o2200–o2201. doi: 10.1107/S1600536810030059

2-Amino-5-bromopyridinium 3-carboxyprop-2-enoate

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

PMCID: PMC3007912 PMID: 21588574

Abstract

In the title salt, C₅H₆BrN₂ ⁺·C₄H₃O₄ ⁻, the 2-amino-5-bromopyridinium cation and hydrogen maleate anion are planar, with maximum deviations from their mean planes of 0.016 (1) and 0.039 (1) Å, respectively. An intramolecular O—H⋯O hydrogen bond generates an S(7) ring motif in the anion. In the crystal, the protonated N atom and the 2-amino group of the cation are hydrogen-bonded to the carboxylate O atoms of the anion via a pair of N—H⋯O hydrogen bonds, forming an R ₂ ²(8) ring motif. The motifs are linked into a two-dimensional network parallel to (011) by N—H⋯O and C—H⋯O hydrogen bonds.

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997 ▶); Katritzky et al. (1996 ▶). For details of maleic acid, see; Bowes et al. (2003 ▶); Jin et al. (2003 ▶); Lah & Leban (2003 ▶); Allen (2002 ▶). For bond-length data, see: Allen et al. (1987 ▶). For details of hydrogen bonding, see: Jeffrey & Saenger (1991 ▶); Jeffrey (1997 ▶); Scheiner (1997 ▶). 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

C₅H₆BrN₂ ⁺·C₄H₃O₄ ⁻
M _r = 289.09
Triclinic,
a = 5.7434 (1) Å
b = 9.5871 (1) Å
c = 10.3034 (2) Å
α = 80.455 (1)°
β = 74.175 (1)°
γ = 85.123 (1)°
V = 537.80 (2) Å³
Z = 2
Mo Kα radiation
μ = 3.82 mm⁻¹
T = 100 K
0.55 × 0.26 × 0.17 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.226, T _max = 0.554
17591 measured reflections
4705 independent reflections
4235 reflections with I > 2σ(I)
R _int = 0.020

Refinement

R[F ² > 2σ(F ²)] = 0.024
wR(F ²) = 0.064
S = 1.06
4705 reflections
157 parameters
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 1.11 e Å⁻³
Δρ_min = −0.70 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/S1600536810030059/ci5141sup1.cif

e-66-o2200-sup1.cif^{(15.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810030059/ci5141Isup2.hkl

e-66-o2200-Isup2.hkl^{(225.8KB, 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—H1O1⋯O3	0.88	1.57	2.4380 (13)	171
N1—H1N1⋯O4ⁱ	0.87 (2)	1.88 (2)	2.7426 (13)	169 (2)
N2—H1N2⋯O3ⁱ	0.84 (2)	2.01 (2)	2.8495 (14)	174 (2)
N2—H2N2⋯O2ⁱⁱ	0.82 (2)	2.14 (2)	2.9534 (13)	176 (2)
C3—H3A⋯O2	0.93	2.37	3.2937 (14)	171
C5—H5A⋯O4ⁱⁱⁱ	0.93	2.39	3.3051 (14)	167

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

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-bonding interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). Maleic acid, the Z isomer of butenedioic acid, has been used as a simple building block in supramolecular architectures in two and three dimensions (Bowes et al., 2003; Jin et al., 2003). The maleic acid anion can exist in the fully deprotonated form or as hydrogen maleate with one of the carboxyl groups protonated (Lah & Leban, 2003). Several singly dissociated maleate salts are reported in the Cambridge Structural Database (Version 5.29; Allen, 2002). Since our aim is to study some interesting hydrogen-bonding interactions, the crystal structure of the title salt is presented here.

The asymmetric unit (Fig. 1) contains one 2-amino-5-bromopyridinium cation and one hydrogen maleate anion, indicating that proton transfer has occurred during the co-crystallisation experiment. In the 2-amino-5-bromopyridinium cation, a wider than normal angle (C5—N1—C1 = 123.02 (9)°) is subtented at the protonated N1 atom. The 2-amino-5-bromopyridinium cation is essentially planar, with a maximum deviation of 0.016 (1) Å for atom Br1. The bond lengths (Allen et al., 1987) and angles are normal.

In the crystal packing (Fig. 2), the protonated N1 atom and the 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O3 and O4) via a pair of intermolecular N1—H1N1···O4 and N2—H1N2···O3 hydrogen bonds forming an R₂²(8) ring motif (Bernstein et al., 1995). There is an intramolecular O1—H1O1···O3 hydrogen bond in the hydrogen maleate anion, which generates an S(7) ring motif. Furthermore these two motifs are connected via N2—H2N2···O2, C3—H3A···O2 and C5—H5A···O4 (Table 1) hydrogen bonds, forming a two-dimensional network parallel to the (011) plane.

Experimental

A hot methanol solution (20 ml) of 2-amino-5-bromopyridine (43 mg, Aldrich) and maleic acid (29 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 crystals of the title compound appeared after a few days.