organic compounds
a]quinoxalin-11-ium dibromide
of 2-azaniumyl-3-bromo-6-oxo-5,6-dihydropyrido[1,2-aDepartment of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India, and bNational Taras Shevchenko University, Department of Chemistry, Volodymyrska str. 64, 01601 Kyiv, Ukraine
*Correspondence e-mail: nsharkina@ukr.net
The title salt, C12H10BrN3O2+·2Br−, was synthesized from the reaction of N1,N4-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.
CCDC reference: 1036569
1. 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).
2. Experimental
2.1. Crystal data
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2.3. Refinement
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Data collection: SMART (Bruker, 2003); cell 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.
Supporting information
CCDC reference: 1036569
https://doi.org/10.1107/S2056989014026127/xu5829sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S2056989014026127/xu5829Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S2056989014026127/xu5829Isup3.cml
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.
H atoms were placed in calculated positions and treated as riding on their parent atoms with C—H = 0.95 Å, N—H = 0.88 or 0.91 Å. Uiso(H) = 1.5Ueq(N) for the amino-H atoms and 1.2Ueq(C,N) for the others.
Quinoxalines are an important class of
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 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
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 Caro—Namine 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-Namine 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 π–π interations are evident in the hydrocarbon layer in title compound.
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 Hammonium atoms and Hpyrazine N—H group are involved in hydrogen bonds with two different bromide ions, and each anion accepts hydrogen bonds from three different cations. No intermolecularFor 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).
Data collection: SMART (Bruker, 2003); cell
SAINT (Bruker, 2003); data reduction: SAINT (Bruker, 2003); 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 (Brandenberg & Putz, 2006).Fig. 1. The molecular conformation and atom-numbering scheme for the title compound, with non-H atoms drawn as 40% probability displacement ellipsoids. |
C12H10BrN3O2+·2Br− | F(000) = 864 |
Mr = 451.96 | Dx = 2.179 Mg m−3 |
Monoclinic, P21/c | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2ybc | Cell parameters from 999 reflections |
a = 5.6782 (2) Å | θ = 2.6–28.6° |
b = 11.9822 (4) Å | µ = 8.78 mm−1 |
c = 20.2528 (7) Å | T = 100 K |
β = 90.891 (2)° | Block, yellow |
V = 1377.78 (8) Å3 | 0.30 × 0.25 × 0.20 mm |
Z = 4 |
Bruker SMART APEX CCD diffractometer | 2424 independent reflections |
Radiation source: fine-focus sealed tube | 1804 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.106 |
ω scans | θmax = 25.0°, θmin = 2.0° |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | h = −6→6 |
Tmin = 0.178, Tmax = 0.273 | k = −14→14 |
14369 measured reflections | l = −23→24 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.047 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.130 | H-atom parameters constrained |
S = 0.97 | w = 1/[σ2(Fo2) + (0.0801P)2] where P = (Fo2 + 2Fc2)/3 |
2424 reflections | (Δ/σ)max < 0.001 |
173 parameters | Δρmax = 1.23 e Å−3 |
0 restraints | Δρmin = −0.88 e Å−3 |
C12H10BrN3O2+·2Br− | V = 1377.78 (8) Å3 |
Mr = 451.96 | Z = 4 |
Monoclinic, P21/c | Mo Kα radiation |
a = 5.6782 (2) Å | µ = 8.78 mm−1 |
b = 11.9822 (4) Å | T = 100 K |
c = 20.2528 (7) Å | 0.30 × 0.25 × 0.20 mm |
β = 90.891 (2)° |
Bruker SMART APEX CCD diffractometer | 2424 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2001) | 1804 reflections with I > 2σ(I) |
Tmin = 0.178, Tmax = 0.273 | Rint = 0.106 |
14369 measured reflections |
R[F2 > 2σ(F2)] = 0.047 | 0 restraints |
wR(F2) = 0.130 | H-atom parameters constrained |
S = 0.97 | Δρmax = 1.23 e Å−3 |
2424 reflections | Δρmin = −0.88 e Å−3 |
173 parameters |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > 2sigma(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
C1 | 1.1684 (11) | 0.3466 (5) | 0.6250 (3) | 0.0348 (16) | |
H1 | 1.1805 | 0.3779 | 0.5821 | 0.042* | |
C2 | 1.3279 (12) | 0.3771 (5) | 0.6724 (3) | 0.0404 (17) | |
H2 | 1.4479 | 0.4297 | 0.6628 | 0.049* | |
C3 | 1.3135 (12) | 0.3313 (6) | 0.7341 (3) | 0.0432 (18) | |
H3 | 1.4246 | 0.3511 | 0.7676 | 0.052* | |
C4 | 1.1375 (12) | 0.2564 (6) | 0.7472 (3) | 0.0408 (17) | |
H4 | 1.1293 | 0.2230 | 0.7896 | 0.049* | |
C5 | 0.9719 (11) | 0.2291 (5) | 0.6989 (3) | 0.0308 (15) | |
C6 | 0.7750 (11) | 0.1557 (5) | 0.7166 (3) | 0.0327 (15) | |
C7 | 0.6487 (11) | 0.1672 (5) | 0.6019 (3) | 0.0284 (14) | |
C8 | 0.4824 (11) | 0.1344 (5) | 0.5543 (3) | 0.0297 (14) | |
H8 | 0.3582 | 0.0851 | 0.5655 | 0.036* | |
C9 | 0.5012 (11) | 0.1750 (5) | 0.4905 (3) | 0.0287 (14) | |
C10 | 0.6803 (11) | 0.2482 (5) | 0.4745 (3) | 0.0272 (14) | |
C11 | 0.8407 (11) | 0.2812 (5) | 0.5212 (3) | 0.0294 (14) | |
H11 | 0.9619 | 0.3323 | 0.5104 | 0.035* | |
C12 | 0.8249 (11) | 0.2387 (5) | 0.5857 (3) | 0.0252 (14) | |
N1 | 0.9939 (8) | 0.2736 (4) | 0.6368 (2) | 0.0262 (11) | |
N2 | 0.6287 (9) | 0.1254 (4) | 0.6658 (2) | 0.0319 (12) | |
H2A | 0.5160 | 0.0770 | 0.6737 | 0.038* | |
N3 | 0.6987 (9) | 0.2912 (4) | 0.4080 (2) | 0.0343 (13) | |
H1N3 | 0.8278 | 0.3360 | 0.4054 | 0.052* | |
H2N3 | 0.5673 | 0.3314 | 0.3976 | 0.052* | |
H3N3 | 0.7126 | 0.2334 | 0.3792 | 0.052* | |
O1 | 0.7430 (8) | 0.1251 (4) | 0.7735 (2) | 0.0428 (12) | |
Br1 | 0.82448 (12) | 0.04974 (5) | 0.33038 (3) | 0.0399 (2) | |
Br2 | 0.21399 (13) | 0.05913 (6) | 0.91141 (4) | 0.0478 (3) | |
Br3 | 0.26693 (12) | 0.12868 (6) | 0.42784 (3) | 0.0388 (2) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.035 (4) | 0.036 (4) | 0.033 (4) | −0.004 (3) | 0.000 (3) | 0.003 (3) |
C2 | 0.038 (4) | 0.036 (4) | 0.047 (4) | −0.002 (3) | −0.002 (3) | −0.002 (3) |
C3 | 0.038 (5) | 0.053 (5) | 0.038 (4) | 0.003 (4) | −0.005 (3) | −0.015 (4) |
C4 | 0.039 (4) | 0.053 (4) | 0.030 (4) | 0.001 (3) | −0.002 (3) | −0.007 (3) |
C5 | 0.031 (4) | 0.040 (4) | 0.021 (3) | 0.004 (3) | 0.002 (3) | −0.005 (3) |
C6 | 0.030 (4) | 0.040 (4) | 0.028 (4) | 0.006 (3) | −0.002 (3) | −0.008 (3) |
C7 | 0.036 (4) | 0.031 (4) | 0.018 (3) | 0.002 (3) | 0.002 (3) | −0.001 (3) |
C8 | 0.026 (4) | 0.031 (3) | 0.032 (4) | 0.001 (3) | 0.004 (3) | 0.000 (3) |
C9 | 0.029 (4) | 0.033 (3) | 0.024 (3) | 0.004 (3) | −0.008 (3) | −0.005 (3) |
C10 | 0.030 (4) | 0.035 (4) | 0.016 (3) | 0.005 (3) | 0.006 (2) | −0.002 (3) |
C11 | 0.023 (4) | 0.035 (4) | 0.030 (3) | −0.002 (3) | 0.007 (3) | −0.002 (3) |
C12 | 0.026 (4) | 0.027 (3) | 0.022 (3) | 0.000 (3) | 0.003 (3) | −0.002 (3) |
N1 | 0.026 (3) | 0.030 (3) | 0.023 (3) | 0.001 (2) | 0.001 (2) | −0.002 (2) |
N2 | 0.033 (3) | 0.037 (3) | 0.026 (3) | −0.002 (2) | 0.005 (2) | 0.002 (2) |
N3 | 0.041 (4) | 0.043 (3) | 0.020 (3) | 0.005 (2) | 0.004 (2) | 0.002 (2) |
O1 | 0.050 (3) | 0.062 (3) | 0.016 (2) | −0.007 (2) | 0.008 (2) | 0.004 (2) |
Br1 | 0.0317 (5) | 0.0464 (5) | 0.0415 (4) | −0.0044 (3) | 0.0032 (3) | −0.0017 (3) |
Br2 | 0.0423 (5) | 0.0435 (5) | 0.0579 (5) | −0.0028 (3) | 0.0115 (4) | −0.0072 (3) |
Br3 | 0.0370 (5) | 0.0460 (5) | 0.0333 (4) | 0.0011 (3) | −0.0044 (3) | −0.0048 (3) |
C1—N1 | 1.346 (7) | C7—N2 | 1.394 (7) |
C1—C2 | 1.359 (9) | C8—C9 | 1.387 (8) |
C1—H1 | 0.9500 | C8—H8 | 0.9500 |
C2—C3 | 1.368 (9) | C9—C10 | 1.385 (9) |
C2—H2 | 0.9500 | C9—Br3 | 1.907 (6) |
C3—C4 | 1.372 (10) | C10—C11 | 1.362 (8) |
C3—H3 | 0.9500 | C10—N3 | 1.449 (7) |
C4—C5 | 1.384 (8) | C11—C12 | 1.405 (8) |
C4—H4 | 0.9500 | C11—H11 | 0.9500 |
C5—N1 | 1.374 (7) | C12—N1 | 1.462 (7) |
C5—C6 | 1.471 (9) | N2—H2A | 0.8800 |
C6—O1 | 1.225 (7) | N3—H1N3 | 0.9100 |
C6—N2 | 1.361 (8) | N3—H2N3 | 0.9100 |
C7—C12 | 1.361 (8) | N3—H3N3 | 0.9100 |
C7—C8 | 1.395 (8) | ||
N1—C1—C2 | 122.3 (6) | C8—C9—C10 | 120.5 (6) |
N1—C1—H1 | 118.9 | C8—C9—Br3 | 117.1 (5) |
C2—C1—H1 | 118.9 | C10—C9—Br3 | 122.4 (4) |
C1—C2—C3 | 119.2 (7) | C11—C10—C9 | 120.5 (5) |
C1—C2—H2 | 120.4 | C11—C10—N3 | 119.0 (6) |
C3—C2—H2 | 120.4 | C9—C10—N3 | 120.5 (5) |
C2—C3—C4 | 119.6 (6) | C10—C11—C12 | 119.2 (6) |
C2—C3—H3 | 120.2 | C10—C11—H11 | 120.4 |
C4—C3—H3 | 120.2 | C12—C11—H11 | 120.4 |
C3—C4—C5 | 120.4 (6) | C7—C12—C11 | 120.7 (6) |
C3—C4—H4 | 119.8 | C7—C12—N1 | 119.1 (5) |
C5—C4—H4 | 119.8 | C11—C12—N1 | 120.2 (5) |
N1—C5—C4 | 119.0 (6) | C1—N1—C5 | 119.5 (5) |
N1—C5—C6 | 122.3 (5) | C1—N1—C12 | 122.5 (5) |
C4—C5—C6 | 118.7 (6) | C5—N1—C12 | 118.0 (5) |
O1—C6—N2 | 122.2 (6) | C6—N2—C7 | 123.2 (5) |
O1—C6—C5 | 122.1 (6) | C6—N2—H2A | 118.4 |
N2—C6—C5 | 115.7 (5) | C7—N2—H2A | 118.4 |
C12—C7—C8 | 120.2 (5) | C10—N3—H1N3 | 109.5 |
C12—C7—N2 | 121.4 (5) | C10—N3—H2N3 | 109.5 |
C8—C7—N2 | 118.5 (6) | H1N3—N3—H2N3 | 109.5 |
C9—C8—C7 | 119.0 (6) | C10—N3—H3N3 | 109.5 |
C9—C8—H8 | 120.5 | H1N3—N3—H3N3 | 109.5 |
C7—C8—H8 | 120.5 | H2N3—N3—H3N3 | 109.5 |
N1—C1—C2—C3 | 0.9 (10) | N2—C7—C12—C11 | −179.2 (5) |
C1—C2—C3—C4 | −0.7 (11) | C8—C7—C12—N1 | 178.6 (5) |
C2—C3—C4—C5 | −1.5 (11) | N2—C7—C12—N1 | −1.1 (9) |
C3—C4—C5—N1 | 3.4 (10) | C10—C11—C12—C7 | −1.4 (9) |
C3—C4—C5—C6 | −175.0 (6) | C10—C11—C12—N1 | −179.5 (5) |
N1—C5—C6—O1 | −172.7 (6) | C2—C1—N1—C5 | 1.1 (9) |
C4—C5—C6—O1 | 5.7 (9) | C2—C1—N1—C12 | −178.7 (6) |
N1—C5—C6—N2 | 6.4 (8) | C4—C5—N1—C1 | −3.2 (9) |
C4—C5—C6—N2 | −175.2 (6) | C6—C5—N1—C1 | 175.2 (5) |
C12—C7—C8—C9 | 0.6 (9) | C4—C5—N1—C12 | 176.5 (5) |
N2—C7—C8—C9 | −179.7 (5) | C6—C5—N1—C12 | −5.1 (8) |
C7—C8—C9—C10 | −0.9 (9) | C7—C12—N1—C1 | −178.0 (6) |
C7—C8—C9—Br3 | −179.4 (4) | C11—C12—N1—C1 | 0.1 (9) |
C8—C9—C10—C11 | 0.1 (9) | C7—C12—N1—C5 | 2.3 (8) |
Br3—C9—C10—C11 | 178.4 (4) | C11—C12—N1—C5 | −179.6 (5) |
C8—C9—C10—N3 | −179.5 (5) | O1—C6—N2—C7 | 174.0 (6) |
Br3—C9—C10—N3 | −1.1 (8) | C5—C6—N2—C7 | −5.1 (8) |
C9—C10—C11—C12 | 1.1 (9) | C12—C7—N2—C6 | 2.7 (9) |
N3—C10—C11—C12 | −179.3 (5) | C8—C7—N2—C6 | −177.0 (5) |
C8—C7—C12—C11 | 0.6 (9) |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···Br1i | 0.88 | 2.46 | 3.322 (5) | 167 |
N3—H1N3···Br2ii | 0.91 | 2.53 | 3.432 (5) | 171 |
N3—H2N3···Br2iii | 0.91 | 2.42 | 3.287 (5) | 160 |
N3—H3N3···Br1 | 0.91 | 2.50 | 3.374 (5) | 162 |
C2—H2···Br2iv | 0.95 | 2.91 | 3.813 (6) | 160 |
C3—H3···Br1v | 0.95 | 2.85 | 3.752 (7) | 160 |
C8—H8···Br1i | 0.95 | 2.86 | 3.672 (6) | 144 |
C11—H11···Br2ii | 0.95 | 2.80 | 3.639 (6) | 148 |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x+1, −y+1/2, z−1/2; (iii) x, −y+1/2, z−1/2; (iv) −x+2, y+1/2, −z+3/2; (v) x+1, −y+1/2, z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
N2—H2A···Br1i | 0.88 | 2.46 | 3.322 (5) | 167 |
N3—H1N3···Br2ii | 0.91 | 2.53 | 3.432 (5) | 171 |
N3—H2N3···Br2iii | 0.91 | 2.42 | 3.287 (5) | 160 |
N3—H3N3···Br1 | 0.91 | 2.50 | 3.374 (5) | 162 |
C2—H2···Br2iv | 0.95 | 2.91 | 3.813 (6) | 160 |
C3—H3···Br1v | 0.95 | 2.85 | 3.752 (7) | 160 |
C8—H8···Br1i | 0.95 | 2.86 | 3.672 (6) | 144 |
C11—H11···Br2ii | 0.95 | 2.80 | 3.639 (6) | 148 |
Symmetry codes: (i) −x+1, −y, −z+1; (ii) x+1, −y+1/2, z−1/2; (iii) x, −y+1/2, z−1/2; (iv) −x+2, y+1/2, −z+3/2; (v) x+1, −y+1/2, z+1/2. |
Acknowledgements
The authors are grateful to the Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, UP 208 016, India, for X-ray data collection.
References
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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 Caro—Namine 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-Namine 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 Hammonium atoms and Hpyrazine 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.