Crystal structure of 2-aza­niumyl-3-bromo-6-oxo-5,6-di­hydro­pyrido[1,2-a]quinoxalin-11-ium dibromide

Md Serajul Haque Faizi; Natalia O Sharkina; Turganbay S Iskenderov

doi:10.1107/S2056989014026127

. 2015 Jan 1;71(Pt 1):o17–o18. doi: 10.1107/S2056989014026127

Crystal structure of 2-azaniumyl-3-bromo-6-oxo-5,6-dihydropyrido[1,2-a]quinoxalin-11-ium dibromide

Md Serajul Haque Faizi ^a, Natalia O Sharkina ^b,^*, Turganbay S Iskenderov ^b

PMCID: PMC4331889 PMID: 25705482

Abstract

The title salt, C₁₂H₁₀BrN₃O²⁺·2Br⁻, was synthesized from the reaction of N ¹,N ⁴-bis(pyridin-2-ylmethylidene)benzene-1,4-diamine and bromine in a methanol solution. All non-H atoms of the 2-azaniumyl-3-bromo-6-oxo-5,6-dihydropyrido[1,2-a]quinoxalin-11-ium cation are nearly coplanar, the maximum deviation being 0.114 (4) Å. In the crystal, the cations and anions are linked through N—H⋯Br hydrogen bonds and weak C—H⋯Br interactions, forming a three-dimensional supramolecular architecture. A short Br⋯Br contact [3.3088 (9) Å] is observed in the crystal.

Keywords: crystal structure; bromide; pyrido[1,2-a]quinoxalin-11-ium; C—H⋯Br interactions

Related literature

For applications of quinoxalines, see: Duffy et al. (2002 ▸); Gazit et al. (1996 ▸); Harmenberg et al. (1991 ▸); Naylor et al. (1993 ▸). For types of quinoxalines and a structure similar to title compound, see: Eiden & Peter (1966 ▸); Koner & Ray (2008 ▸); Fritsky et al. (2006 ▸); Kanderal et al. (2005 ▸); Moroz et al. (2012 ▸). For background to and applications of related compounds, see: Faizi & Sen (2014 ▸); Faizi et al. (2014 ▸). graphic file with name e-71-00o17-scheme1.jpg

Experimental

Crystal data

C₁₂H₁₀BrN₃O²⁺·2Br⁻
M _r = 451.96
Monoclinic,
a = 5.6782 (2) Å
b = 11.9822 (4) Å
c = 20.2528 (7) Å
β = 90.891 (2)°
V = 1377.78 (8) Å³
Z = 4
Mo Kα radiation
μ = 8.78 mm⁻¹
T = 100 K
0.30 × 0.25 × 0.20 mm

Data collection

Bruker SMART APEX CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2001 ▸) T _min = 0.178, T _max = 0.273
14369 measured reflections
2424 independent reflections
1804 reflections with I > 2σ(I)
R _int = 0.106

Refinement

R[F ² > 2σ(F ²)] = 0.047
wR(F ²) = 0.130
S = 0.97
2424 reflections
173 parameters
H-atom parameters constrained
Δρ_max = 1.23 e Å⁻³
Δρ_min = −0.88 e Å⁻³

Data collection: SMART (Bruker, 2003 ▸); cell refinement: SAINT (Bruker, 2003 ▸); data reduction: SAINT; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▸); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▸); molecular graphics: DIAMOND (Brandenberg & Putz, 2006 ▸); software used to prepare material for publication: DIAMOND.

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S2056989014026127/xu5829sup1.cif

e-71-00o17-sup1.cif^{(20.7KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S2056989014026127/xu5829Isup2.hkl

e-71-00o17-Isup2.hkl^{(119.1KB, hkl)}

Click here for additional data file.^{(4.8KB, cml)}

Supporting information file. DOI: 10.1107/S2056989014026127/xu5829Isup3.cml

Click here for additional data file.^{(1.3MB, tif)}

. DOI: 10.1107/S2056989014026127/xu5829fig1.tif

The molecular conformation and atom-numbering scheme for the title compound, with non-H atoms drawn as 40% probability displacement ellipsoids.

CCDC reference: 1036569

Additional supporting information: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (, ).

DHA	DH	HA	D A	DHA
N2H2ABr1ⁱ	0.88	2.46	3.322(5)	167
N3H1N3Br2ⁱⁱ	0.91	2.53	3.432(5)	171
N3H2N3Br2ⁱⁱⁱ	0.91	2.42	3.287(5)	160
N3H3N3Br1	0.91	2.50	3.374(5)	162
C2H2Br2^iv	0.95	2.91	3.813(6)	160
C3H3Br1^v	0.95	2.85	3.752(7)	160
C8H8Br1ⁱ	0.95	2.86	3.672(6)	144
C11H11Br2ⁱⁱ	0.95	2.80	3.639(6)	148

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

Acknowledgments

The authors are grateful to the Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India, for X-ray data collection.

supplementary crystallographic information

S1. Comment

Quinoxalines are an important class of heterocyclic compounds, some of which are found to be useful as fluorophores, dyes, and antibiotics (Duffy et al., 2002; Gazit et al., 1996). Many drug candidates bearing quinoxaline core structures are in clinical trials in antiviral, anticancer and CNS (central nervous system) therapeutic areas (Harmenberg et al., 1991; Naylor et al., 1993). The present work is a part of an ongoing structural study of Schiff bases and their utilization in the synthesis of previously unknown organic and polynuclear coordination compounds (Faizi & Sen, 2014; Faizi et al., 2014; Moroz et al., 2012), and we report here synthesis and structure of 2-azaniumyl-3-bromo-6-oxo-5,6-dihydropyrido[1,2-a]quinoxalin-11-ium bromide (ABODQ). There are very few examples similar to title compound have been reported in the literature (Eiden & Peter, 1966).

The title compound was synthesized from the reaction of two equimolar amounts of molecular bromine and pyridine derivative Schiff base N1,N4-bis(pyridine-2-ylmethylene) benzene-1,4-diamine (BPYBD). The cyclization occurs by oxidation of BPYBD, reduction of molecular bromine and finally hydrolysis of the imine bond which creates the dication at two of the nitrogen atoms in the quinoxaline ring system.

In the structure of the title bromide salt, the dication is essentially planar with a longer C10—N3 distance of 1.45 (3) Å, compared to the usual C_aro—N_amine single bond distance of 1.43 (3) Å. This might be due to the electron withdrawing effect of positively charged pyridine, which increased the C-N_amine bond order. Other C—C and C—N bond distances are well within the limits expected for aromatic rings (Koner & Ray, 2008; Kanderal et al., 2005; Fritsky et al., 2006).

The asymmetric unit contains a discrete 2-azaniumyl-3-bromo-6-oxo-5,6-dihydropyrido[1,2-a]quinoxalin-11-ium cation, with a protonated amine, pyridine group, and two bromide anion (Fig 1). In title compound, the ions are connected into a three dimensional hydrogen-bonded network via N—H···Br and C—H···Br hydrogen bonds (Table 1). All H_ammonium atoms and H_pyrazine N—H group are involved in hydrogen bonds with two different bromide ions, and each anion accepts hydrogen bonds from three different cations. No intermolecular π–π interations are evident in the hydrocarbon layer in title compound.

S2. Experimental

Molecular bromine (220 mg, 72.0 mL, 1.40 mmol) was added to a methanolic solution (10 ml) of Schiff base, N1,N4-bis (pyridine-2-ylmethylene)benzene-1,4-diamine (BPYBD) (197 mg, 0.70 mmol). The color of the solution was immediately changed from yellow to orange. The reaction mixture was stirred for 4 h at room temperature under hood. The resulting yellow precipitate was recovered by filtration, washed several times with a small portions of acetone and then with diethyl ether to give 200 mg (64%) of 2-azaniumyl-3-bromo-6-oxo-5,6-dihydropyrido [1,2-a]quinoxalin-11-ium bromide (ABODQ). The crystal of the title compound suitable for X-ray analysis was obtained within 3 days by slow evaporation of the methanol solvent.