2-Amino-5-bromo­pyridinium 6-oxo-1,6-dihydro­pyridine-2-carboxyl­ate monohydrate

Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536810030916

. 2010 Aug 11;66(Pt 9):o2246–o2247. doi: 10.1107/S1600536810030916

2-Amino-5-bromopyridinium 6-oxo-1,6-dihydropyridine-2-carboxylate monohydrate

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

PMCID: PMC3008071 PMID: 21588612

Abstract

In the crystal structure of the title salt, C₅H₆BrN₂ ⁺·C₆H₄NO₃ ⁻·H₂O, 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 ion pairs are further connected via O—H⋯O, N—H⋯O, N—H⋯Br and C—H⋯O hydrogen bonds, forming a two-dimensional network parallel to the bc plane. The water molecules self-assemble through O—H⋯O hydrogen bonds, forming one-dimensional supramolecular chains along the a axis, with graph-set notation C ₂ ²(4).

Related literature

For background to the chemistry of substituted pyridines, see: Pozharski et al. (1997 ▶); Katritzky et al. (1996 ▶). For details of 6-hydroxypicolinic acid, see: Sun et al. (2004 ▶); Soares-Santos et al. (2003 ▶). For a related structure, see: Sawada & Ohashi (1998 ▶). For details of hydrogen bonding, see: Jeffrey & Saenger (1991 ▶); Jeffrey (1997 ▶); Scheiner (1997 ▶). For hydrogen-bond motifs, see: Bernstein et al. (1995 ▶).

Experimental

Crystal data

C₅H₆BrN₂ ⁺·C₆H₄NO₃ ⁻·H₂O
M _r = 330.15
Orthorhombic,
a = 3.8616 (1) Å
b = 15.8227 (2) Å
c = 20.8961 (3) Å
V = 1276.77 (4) Å³
Z = 4
Mo Kα radiation
μ = 3.23 mm⁻¹
T = 296 K
0.35 × 0.18 × 0.12 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.400, T _max = 0.694
8884 measured reflections
3718 independent reflections
3105 reflections with I > 2σ(I)
R _int = 0.022

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.097
S = 1.09
3718 reflections
172 parameters
3 restraints
H-atom parameters constrained
Δρ_max = 0.37 e Å⁻³
Δρ_min = −0.32 e Å⁻³
Absolute structure: Flack (1983 ▶), 1482 Friedel pairs
Flack parameter: 0.011 (12)

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/S1600536810030916/is2585sup1.cif

e-66-o2246-sup1.cif^{(17.2KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810030916/is2585Isup2.hkl

e-66-o2246-Isup2.hkl^{(178.6KB, 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—H1B⋯O2ⁱ	0.86	1.79	2.640 (4)	171
O1W—H1W⋯O2ⁱⁱ	0.94	2.17	2.730 (5)	117
N2—H2A⋯O3ⁱ	0.86	2.04	2.896 (4)	172
N2—H2B⋯O1ⁱⁱⁱ	0.86	1.96	2.819 (4)	173
O1W—H2W⋯O1Wⁱⁱ	0.94	2.02	2.782 (9)	137
N3—H3B⋯Br1	0.86	2.84	3.681 (3)	168
C3—H3A⋯O1	0.93	2.44	3.351 (4)	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-bond interactions (Jeffrey & Saenger, 1991; Jeffrey, 1997; Scheiner, 1997). 6-hydroxypioclinic acid has interesting characteristics: firstly, it was characterized by a similar enol-keto tautomerism due to the labile hydrogen atom of -OH group in α-position migrating easily to the basic pyridine N atom; secondly, the multiple coordination sites such as the carbonyl oxygen, the amide nitrogen and carboxylate oxygen atoms are able to coordinate with various metal ions (Sun et al., 2004; Soares-Santos et al., 2003). In order to study some interesting hydrogen bonding interactions of these compounds, the synthesis and structure of the title salt is presented here.

The asymmetric unit, (Fig. 1), contains a 2-amino-5-bromopyridinium cation, a 6-oxo-1,6-dihydropyridine-2-carboxylate anion and a water molecule. The 2-amino-5-bromopyridinium cation is essentially planar, with a maximum deviation of 0.019 (3) Å for atom N1. In the 2-amino-5-bromopyridinium cation, a wider than normal angle [C1—N1—C5 = 122.7 (3)°] is subtented at the protonated N1 atom. The anion exists in the keto-enol tautomerism of the -CONH moiety. Similar form is also observed in the crystal structure of 2-oxo-1,2-dihydropyridine-6-carboxylic acid (Sawada & Ohashi, 1998).

In the crystal packing, (Fig. 2), the protonated N1 atom and the 2-amino group (N2) are hydrogen-bonded to the carboxylate oxygen atoms (O2 and O3) via a pair of intermolecular N—H···O hydrogen bonds, forming a ring motif R₂²(8) (Bernstein et al., 1995). The ion pairs are further connected via O—H···O, N—H···O, N—H···Br and C—H···O (Table 1) hydrogen bonds, forming a two-dimensional network parallel to the bc plane. The water molecules self-assemble through O1W—H2W···O1W hydrogen bonds, forming one-dimensional supramolecular chains along the a axis, with graph-set notation C₂²(4) (Fig. 3).

Experimental

A hot methanol solution (20 ml) of 2-amino-5-bromopyridine (86 mg, Aldrich) and 6-hydroxypicolinic acid (69 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.