organic compounds
6,7-Dichloro-3-(2,4-dichlorobenzyl)quinoxalin-2(1H)-one
aDepartment of Public Health, Xuzhou Medical College, Xuzhou 221000, People's Republic of China., and bOut Patient Department, Xuzhou Airforce College, Xuzhou 221000, People's Republic of China.
*Correspondence e-mail: jsxzzjp@163.com
In the title compound, C15H8Cl4N2O, the quinoxaline ring system is almost planar, with a dihedral angle between the benzene and pyrazine rings of 3.1 (2)°. The 2,4-dichlorophenyl ring is approximately perpendicular to the pyrazine ring, with a dihedral angle of 86.47 (13)° between them. The crystal packing features intermolecular N—H⋯O hydrogen bonds and π–π stacking interactions, with centroid–centroid distances in the range 3.699 (3)–4.054 (3) Å.
Related literature
For the bioactivity of quinoxalin-2(1H)-one derivatives, see: Mensah-Osman et al. (2002); Perez et al. (2002); Quint et al. (2002); Seitz et al. (2002).
Experimental
Crystal data
|
Refinement
|
Data collection: SMART (Bruker, 1998); cell SAINT (Bruker, 1999); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.
Supporting information
https://doi.org/10.1107/S160053681203098X/sj5253sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681203098X/sj5253Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S160053681203098X/sj5253Isup3.cml
In a 10 ml Emrys reaction vial, 4-(2,4-dichlorobenzylidene)-2-phenyloxazol -5(4H)-one (0.32 g, 1 mmol), 4,5-dichlorobenzene-1,2-diamine (0.18 g, 1 mmol), TFA (0.23 g, 2 mmol) and ethylene glycol (1.5 ml) were mixed and then capped (The automatic mode stirring helped the mixing and uniform heating of the reactants). The mixture was heated for 16 min at 393 K under microwave irradiation. Upon completion, monitored by TLC, the reaction mixture was cooled to room temperature. The solid product was poured into water and neutralized with 10% NaOH, and then collected by filtration, subsequently washed with ethanol and ethylether in sequence to give a pure yellow solid. A single-crystal suitable for X-ray diffraction was obtained from the evaporation of a solution of the title compound in ethanol.
All H atoms were placed in calculated positions, with N—H = 0.86 Å, and C—H=0.93 Å or 0.97 Å and included in the final cycles of
using a riding model, with Uĩso~(H) = 1.2U~eq~(parent atom).Quinoxalin-2(1H)-one derivatives have attracted much attention in the pharmaceutical field due to their diverse bioactivities. These include use as a glutamate blocker (Perez et al. 2002), in the treatment of sensorineural smell disorders (Quint et al. 2002) and as a DNA topoisomerase (Topo) II beta-inhibitor (Mensah-Osman et al. 2002). They also exhibit antimycobacterial activity (Seitz et al. 2002). These reports inspired us to study the relationship between their structures and activities. During the synthesis of some quinoxalin derivatives, the title compound, (I) was isolated and its structure was confirmed by X-ray diffraction. Herein we report this structure.
In the molecular structure (Fig. 1), the quinoxaline ring system is nearly planar with a dihedral angle between the phenyl and pyrazine rings of 3.12(0.22) ° and rms deviations of 0.0135 Å and 0.0210 Å, respectively. The largest deviations from the planes of the two rings are 0.020 (3) Å for C3 and 0.031 (3) Å for C1. The 2,4-dichlorophenyl and pyrazine rings are approximately orthogonal with a dihedral angle of 86.47 (13) ° between them.
The crystal packing is stabilized by intermolecular N—H···O hydrogen bonds that form inversion dimers. In addition π–π stacking interactions are also found involving the C3–C8 and C10–C15 phenyl rings (Fig. 2). The centroid-to-centroid distances, plane-plane distances and displacement distances are as follows: 4.054 (3), 3.404 (2) and 2.201 Å (C3–C8 to C3–C8; symmetry code: 1-X,1-Y,1-Z); 3.699 (3), 3.415 (2) and 1.421 Å (C3–C8 to C3–C8; symmetry code: 2-X,1-Y,1-Z); 3.964 (3), 3.615 (2) and 1.626 Å (C10–C15 to C10–C15; symmetry code: 1-X,2-Y, 2-Z).
For the bioactivity of quinoxalin-2(1H)-one derivatives, see: Mensah-Osman et al. (2002); Perez et al. (2002); Quint et al. (2002); Seitz et al. (2002).
Data collection: SMART (Bruker, 1998); cell
SAINT (Bruker, 1999); data reduction: SAINT (Bruker, 1999); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).Fig. 1. The structure of (I), showing 30% probability displacement ellipsoids and the atom-numbering scheme. | |
Fig. 2. Crystal packing of (I), with hydrogen bonds drawn as dashed lines. |
C15H8Cl4N2O | Z = 2 |
Mr = 374.03 | F(000) = 376 |
Triclinic, P1 | Dx = 1.663 Mg m−3 |
Hall symbol: -P 1 | Mo Kα radiation, λ = 0.71073 Å |
a = 7.7150 (7) Å | Cell parameters from 742 reflections |
b = 8.2058 (8) Å | θ = 2.9–26.1° |
c = 11.9722 (12) Å | µ = 0.79 mm−1 |
α = 83.771 (1)° | T = 298 K |
β = 84.362 (1)° | Prism, colorless |
γ = 84.298 (2)° | 0.16 × 0.09 × 0.05 mm |
V = 746.79 (12) Å3 |
Bruker SMART CCD area-detector diffractometer | 2590 independent reflections |
Radiation source: fine-focus sealed tube | 1364 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.036 |
φ and ω scans | θmax = 25.0°, θmin = 2.5° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −9→5 |
Tmin = 0.884, Tmax = 0.961 | k = −9→9 |
3811 measured reflections | l = −13→14 |
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)] = 0.055 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.103 | H-atom parameters constrained |
S = 1.01 | w = 1/[σ2(Fo2) + (0.0247P)2] where P = (Fo2 + 2Fc2)/3 |
2590 reflections | (Δ/σ)max < 0.001 |
199 parameters | Δρmax = 0.27 e Å−3 |
0 restraints | Δρmin = −0.26 e Å−3 |
C15H8Cl4N2O | γ = 84.298 (2)° |
Mr = 374.03 | V = 746.79 (12) Å3 |
Triclinic, P1 | Z = 2 |
a = 7.7150 (7) Å | Mo Kα radiation |
b = 8.2058 (8) Å | µ = 0.79 mm−1 |
c = 11.9722 (12) Å | T = 298 K |
α = 83.771 (1)° | 0.16 × 0.09 × 0.05 mm |
β = 84.362 (1)° |
Bruker SMART CCD area-detector diffractometer | 2590 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1364 reflections with I > 2σ(I) |
Tmin = 0.884, Tmax = 0.961 | Rint = 0.036 |
3811 measured reflections |
R[F2 > 2σ(F2)] = 0.055 | 0 restraints |
wR(F2) = 0.103 | H-atom parameters constrained |
S = 1.01 | Δρmax = 0.27 e Å−3 |
2590 reflections | Δρmin = −0.26 e Å−3 |
199 parameters |
Experimental. The data was obtained at Xuzhou Medical College collected by Jinpeng Zhang. |
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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 | ||
Cl1 | 0.77372 (19) | 0.40780 (15) | 0.26074 (9) | 0.0645 (4) | |
Cl2 | 0.62590 (18) | 0.18395 (14) | 0.47312 (10) | 0.0575 (4) | |
Cl3 | 0.4357 (2) | 1.04383 (15) | 0.75266 (10) | 0.0745 (5) | |
Cl4 | 0.0594 (2) | 0.7248 (2) | 1.09562 (11) | 0.0880 (5) | |
N1 | 0.8827 (5) | 0.8183 (4) | 0.5316 (3) | 0.0447 (10) | |
H1 | 0.9289 | 0.8757 | 0.4739 | 0.054* | |
N2 | 0.7257 (5) | 0.6358 (4) | 0.7161 (3) | 0.0431 (10) | |
O1 | 0.9408 (4) | 1.0040 (4) | 0.6487 (2) | 0.0540 (9) | |
C1 | 0.8754 (6) | 0.8778 (5) | 0.6340 (3) | 0.0406 (12) | |
C2 | 0.7819 (6) | 0.7756 (5) | 0.7279 (3) | 0.0418 (12) | |
C3 | 0.7456 (6) | 0.5778 (5) | 0.6094 (3) | 0.0374 (11) | |
C4 | 0.8206 (6) | 0.6717 (5) | 0.5149 (3) | 0.0356 (11) | |
C5 | 0.8302 (6) | 0.6185 (5) | 0.4072 (3) | 0.0416 (12) | |
H5 | 0.8779 | 0.6820 | 0.3448 | 0.050* | |
C6 | 0.7680 (6) | 0.4710 (5) | 0.3953 (3) | 0.0420 (12) | |
C7 | 0.6994 (6) | 0.3725 (5) | 0.4901 (4) | 0.0399 (11) | |
C8 | 0.6891 (6) | 0.4266 (5) | 0.5954 (3) | 0.0419 (12) | |
H8 | 0.6440 | 0.3613 | 0.6578 | 0.050* | |
C9 | 0.7583 (7) | 0.8441 (6) | 0.8411 (3) | 0.0584 (14) | |
H9A | 0.8507 | 0.7934 | 0.8862 | 0.070* | |
H9B | 0.7706 | 0.9614 | 0.8296 | 0.070* | |
C10 | 0.5845 (7) | 0.8167 (5) | 0.9056 (3) | 0.0426 (12) | |
C11 | 0.4300 (8) | 0.9005 (5) | 0.8721 (3) | 0.0507 (14) | |
C12 | 0.2672 (7) | 0.8752 (5) | 0.9292 (4) | 0.0544 (14) | |
H12 | 0.1657 | 0.9328 | 0.9045 | 0.065* | |
C13 | 0.2608 (7) | 0.7620 (6) | 1.0233 (4) | 0.0562 (14) | |
C14 | 0.4100 (7) | 0.6797 (6) | 1.0607 (4) | 0.0549 (14) | |
H14 | 0.4037 | 0.6059 | 1.1253 | 0.066* | |
C15 | 0.5711 (7) | 0.7057 (5) | 1.0027 (3) | 0.0517 (14) | |
H15 | 0.6717 | 0.6485 | 1.0288 | 0.062* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Cl1 | 0.0842 (11) | 0.0672 (9) | 0.0442 (7) | −0.0149 (8) | 0.0021 (7) | −0.0150 (6) |
Cl2 | 0.0672 (10) | 0.0447 (7) | 0.0626 (8) | −0.0132 (7) | −0.0054 (7) | −0.0079 (6) |
Cl3 | 0.1159 (14) | 0.0603 (8) | 0.0459 (7) | −0.0194 (9) | −0.0035 (8) | 0.0086 (6) |
Cl4 | 0.0741 (12) | 0.1161 (13) | 0.0705 (9) | −0.0285 (10) | 0.0238 (8) | −0.0039 (8) |
N1 | 0.059 (3) | 0.042 (2) | 0.031 (2) | −0.014 (2) | 0.0130 (18) | 0.0019 (17) |
N2 | 0.050 (3) | 0.050 (2) | 0.030 (2) | −0.012 (2) | 0.0019 (19) | −0.0031 (18) |
O1 | 0.070 (3) | 0.0498 (19) | 0.0455 (18) | −0.0295 (19) | 0.0063 (17) | −0.0050 (15) |
C1 | 0.041 (3) | 0.045 (3) | 0.035 (3) | −0.009 (2) | 0.001 (2) | 0.001 (2) |
C2 | 0.045 (3) | 0.049 (3) | 0.031 (2) | −0.012 (3) | 0.003 (2) | −0.004 (2) |
C3 | 0.039 (3) | 0.037 (2) | 0.035 (2) | −0.005 (2) | 0.005 (2) | 0.000 (2) |
C4 | 0.034 (3) | 0.032 (2) | 0.038 (2) | −0.004 (2) | 0.002 (2) | 0.003 (2) |
C5 | 0.049 (3) | 0.038 (3) | 0.035 (2) | −0.008 (2) | 0.003 (2) | 0.004 (2) |
C6 | 0.039 (3) | 0.049 (3) | 0.038 (2) | −0.003 (2) | −0.003 (2) | −0.004 (2) |
C7 | 0.041 (3) | 0.032 (2) | 0.046 (3) | −0.004 (2) | 0.000 (2) | −0.005 (2) |
C8 | 0.046 (3) | 0.039 (3) | 0.037 (3) | −0.009 (2) | 0.004 (2) | 0.007 (2) |
C9 | 0.072 (4) | 0.069 (3) | 0.041 (3) | −0.036 (3) | 0.002 (3) | −0.013 (2) |
C10 | 0.057 (4) | 0.043 (3) | 0.032 (3) | −0.022 (3) | 0.006 (3) | −0.009 (2) |
C11 | 0.087 (5) | 0.037 (3) | 0.030 (3) | −0.014 (3) | −0.002 (3) | −0.004 (2) |
C12 | 0.061 (4) | 0.055 (3) | 0.048 (3) | −0.011 (3) | 0.003 (3) | −0.013 (3) |
C13 | 0.068 (4) | 0.056 (3) | 0.046 (3) | −0.018 (3) | 0.014 (3) | −0.017 (3) |
C14 | 0.069 (4) | 0.060 (3) | 0.037 (3) | −0.024 (3) | 0.007 (3) | −0.003 (2) |
C15 | 0.067 (4) | 0.053 (3) | 0.036 (3) | −0.012 (3) | −0.001 (3) | −0.004 (2) |
Cl1—C6 | 1.740 (4) | C5—H5 | 0.9300 |
Cl2—C7 | 1.738 (4) | C6—C7 | 1.411 (5) |
Cl3—C11 | 1.750 (4) | C7—C8 | 1.374 (5) |
Cl4—C13 | 1.740 (5) | C8—H8 | 0.9300 |
N1—C1 | 1.362 (5) | C9—C10 | 1.505 (6) |
N1—C4 | 1.380 (5) | C9—H9A | 0.9700 |
N1—H1 | 0.8600 | C9—H9B | 0.9700 |
N2—C2 | 1.292 (5) | C10—C11 | 1.388 (6) |
N2—C3 | 1.401 (5) | C10—C15 | 1.399 (5) |
O1—C1 | 1.233 (5) | C11—C12 | 1.393 (6) |
C1—C2 | 1.498 (5) | C12—C13 | 1.380 (6) |
C2—C9 | 1.511 (5) | C12—H12 | 0.9300 |
C3—C8 | 1.387 (5) | C13—C14 | 1.365 (6) |
C3—C4 | 1.407 (5) | C14—C15 | 1.386 (6) |
C4—C5 | 1.398 (5) | C14—H14 | 0.9300 |
C5—C6 | 1.371 (5) | C15—H15 | 0.9300 |
C1—N1—C4 | 124.0 (3) | C7—C8—H8 | 119.8 |
C1—N1—H1 | 118.0 | C3—C8—H8 | 119.8 |
C4—N1—H1 | 118.0 | C10—C9—C2 | 113.7 (4) |
C2—N2—C3 | 119.1 (3) | C10—C9—H9A | 108.8 |
O1—C1—N1 | 123.2 (4) | C2—C9—H9A | 108.8 |
O1—C1—C2 | 122.7 (4) | C10—C9—H9B | 108.8 |
N1—C1—C2 | 114.1 (4) | C2—C9—H9B | 108.8 |
N2—C2—C1 | 123.6 (4) | H9A—C9—H9B | 107.7 |
N2—C2—C9 | 120.6 (4) | C11—C10—C15 | 116.8 (4) |
C1—C2—C9 | 115.8 (4) | C11—C10—C9 | 121.7 (4) |
C8—C3—N2 | 120.0 (3) | C15—C10—C9 | 121.5 (5) |
C8—C3—C4 | 119.0 (4) | C10—C11—C12 | 122.8 (4) |
N2—C3—C4 | 121.0 (4) | C10—C11—Cl3 | 119.6 (4) |
N1—C4—C5 | 121.1 (3) | C12—C11—Cl3 | 117.5 (4) |
N1—C4—C3 | 118.0 (3) | C13—C12—C11 | 118.1 (5) |
C5—C4—C3 | 120.9 (4) | C13—C12—H12 | 121.0 |
C6—C5—C4 | 118.8 (4) | C11—C12—H12 | 121.0 |
C6—C5—H5 | 120.6 | C14—C13—C12 | 120.9 (5) |
C4—C5—H5 | 120.6 | C14—C13—Cl4 | 119.6 (4) |
C5—C6—C7 | 120.7 (4) | C12—C13—Cl4 | 119.4 (5) |
C5—C6—Cl1 | 118.8 (3) | C13—C14—C15 | 120.3 (5) |
C7—C6—Cl1 | 120.4 (3) | C13—C14—H14 | 119.8 |
C8—C7—C6 | 119.9 (4) | C15—C14—H14 | 119.8 |
C8—C7—Cl2 | 120.2 (3) | C14—C15—C10 | 121.0 (5) |
C6—C7—Cl2 | 119.9 (3) | C14—C15—H15 | 119.5 |
C7—C8—C3 | 120.5 (4) | C10—C15—H15 | 119.5 |
C4—N1—C1—O1 | 175.5 (4) | Cl1—C6—C7—Cl2 | 1.9 (5) |
C4—N1—C1—C2 | −4.0 (6) | C6—C7—C8—C3 | 0.1 (7) |
C3—N2—C2—C1 | −2.8 (7) | Cl2—C7—C8—C3 | −179.2 (3) |
C3—N2—C2—C9 | 178.4 (4) | N2—C3—C8—C7 | 176.5 (4) |
O1—C1—C2—N2 | −173.8 (5) | C4—C3—C8—C7 | −2.8 (7) |
N1—C1—C2—N2 | 5.7 (7) | N2—C2—C9—C10 | −39.4 (6) |
O1—C1—C2—C9 | 5.1 (7) | C1—C2—C9—C10 | 141.7 (4) |
N1—C1—C2—C9 | −175.4 (4) | C2—C9—C10—C11 | −70.7 (6) |
C2—N2—C3—C8 | 178.8 (4) | C2—C9—C10—C15 | 109.5 (5) |
C2—N2—C3—C4 | −2.0 (6) | C15—C10—C11—C12 | −1.5 (7) |
C1—N1—C4—C5 | 179.2 (4) | C9—C10—C11—C12 | 178.8 (4) |
C1—N1—C4—C3 | −0.2 (7) | C15—C10—C11—Cl3 | 179.1 (3) |
C8—C3—C4—N1 | −177.2 (4) | C9—C10—C11—Cl3 | −0.7 (6) |
N2—C3—C4—N1 | 3.5 (6) | C10—C11—C12—C13 | 0.3 (7) |
C8—C3—C4—C5 | 3.4 (7) | Cl3—C11—C12—C13 | 179.8 (3) |
N2—C3—C4—C5 | −175.9 (4) | C11—C12—C13—C14 | 1.2 (7) |
N1—C4—C5—C6 | 179.4 (4) | C11—C12—C13—Cl4 | −179.1 (3) |
C3—C4—C5—C6 | −1.2 (7) | C12—C13—C14—C15 | −1.6 (8) |
C4—C5—C6—C7 | −1.5 (7) | Cl4—C13—C14—C15 | 178.7 (3) |
C4—C5—C6—Cl1 | 178.0 (3) | C13—C14—C15—C10 | 0.3 (7) |
C5—C6—C7—C8 | 2.1 (7) | C11—C10—C15—C14 | 1.1 (6) |
Cl1—C6—C7—C8 | −177.4 (3) | C9—C10—C15—C14 | −179.1 (4) |
C5—C6—C7—Cl2 | −178.6 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.86 | 1.93 | 2.789 (4) | 173 |
Symmetry code: (i) −x+2, −y+2, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C15H8Cl4N2O |
Mr | 374.03 |
Crystal system, space group | Triclinic, P1 |
Temperature (K) | 298 |
a, b, c (Å) | 7.7150 (7), 8.2058 (8), 11.9722 (12) |
α, β, γ (°) | 83.771 (1), 84.362 (1), 84.298 (2) |
V (Å3) | 746.79 (12) |
Z | 2 |
Radiation type | Mo Kα |
µ (mm−1) | 0.79 |
Crystal size (mm) | 0.16 × 0.09 × 0.05 |
Data collection | |
Diffractometer | Bruker SMART CCD area-detector |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.884, 0.961 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 3811, 2590, 1364 |
Rint | 0.036 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.055, 0.103, 1.01 |
No. of reflections | 2590 |
No. of parameters | 199 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.27, −0.26 |
Computer programs: SMART (Bruker, 1998), SAINT (Bruker, 1999), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O1i | 0.86 | 1.93 | 2.789 (4) | 173.1 |
Symmetry code: (i) −x+2, −y+2, −z+1. |
Acknowledgements
We thank the Foundation of Xuzhou Medical College (grant No. 201120), a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD), for financial support.
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Quinoxalin-2(1H)-one derivatives have attracted much attention in the pharmaceutical field due to their diverse bioactivities. These include use as a glutamate blocker (Perez et al. 2002), in the treatment of sensorineural smell disorders (Quint et al. 2002) and as a DNA topoisomerase (Topo) II beta-inhibitor (Mensah-Osman et al. 2002). They also exhibit antimycobacterial activity (Seitz et al. 2002). These reports inspired us to study the relationship between their structures and activities. During the synthesis of some quinoxalin derivatives, the title compound, (I) was isolated and its structure was confirmed by X-ray diffraction. Herein we report this structure.
In the molecular structure (Fig. 1), the quinoxaline ring system is nearly planar with a dihedral angle between the phenyl and pyrazine rings of 3.12(0.22) ° and rms deviations of 0.0135 Å and 0.0210 Å, respectively. The largest deviations from the planes of the two rings are 0.020 (3) Å for C3 and 0.031 (3) Å for C1. The 2,4-dichlorophenyl and pyrazine rings are approximately orthogonal with a dihedral angle of 86.47 (13) ° between them.
The crystal packing is stabilized by intermolecular N—H···O hydrogen bonds that form inversion dimers. In addition π–π stacking interactions are also found involving the C3–C8 and C10–C15 phenyl rings (Fig. 2). The centroid-to-centroid distances, plane-plane distances and displacement distances are as follows: 4.054 (3), 3.404 (2) and 2.201 Å (C3–C8 to C3–C8; symmetry code: 1-X,1-Y,1-Z); 3.699 (3), 3.415 (2) and 1.421 Å (C3–C8 to C3–C8; symmetry code: 2-X,1-Y,1-Z); 3.964 (3), 3.615 (2) and 1.626 Å (C10–C15 to C10–C15; symmetry code: 1-X,2-Y, 2-Z).