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In the crystal structure of the title compound, C8H6N2·C6H2Cl2O4, there are two crystallographically independent chloranilic acid (systematic name: 2,5-dichloro-3,6-dihydr­oxy-1,4-benzoquinone) mol­ecules, each of which is located on an inversion center. The quinoxaline ring system makes dihedral angles of 6.09 (9) and 44.50 (9)° with the two chloranilic acid planes. The quinoxaline and the chloranilic acid are connected alternately by O—H...N hydrogen bonds, forming a zigzag chain running along the [20\overline{1}] direction. The chains are stacked along the a axis, forming a layer extending parallel to the (010) plane. The layers are further linked by C—H...O hydrogen bonds.

Supporting information

cif

Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807049483/pk2054sup1.cif
Contains datablocks global, I

hkl

Structure factor file (CIF format) https://doi.org/10.1107/S1600536807049483/pk2054Isup2.hkl
Contains datablock I

CCDC reference: 667339

Key indicators

  • Single-crystal X-ray study
  • T = 95 K
  • Mean [sigma](C-C) = 0.003 Å
  • R factor = 0.044
  • wR factor = 0.102
  • Data-to-parameter ratio = 14.4

checkCIF/PLATON results

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Alert level C PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 2.30 PLAT250_ALERT_2_C Large U3/U1 Ratio for Average U(i,j) Tensor .... 2.07 PLAT333_ALERT_2_C Large Average Benzene C-C Dist. C1 -C3_a 1.44 Ang. PLAT333_ALERT_2_C Large Average Benzene C-C Dist. C4 -C6_b 1.44 Ang. PLAT335_ALERT_2_C Large Benzene C-C Range ....... C4 -C6_b 0.16 Ang.
0 ALERT level A = In general: serious problem 0 ALERT level B = Potentially serious problem 5 ALERT level C = Check and explain 0 ALERT level G = General alerts; check 0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data 5 ALERT type 2 Indicator that the structure model may be wrong or deficient 0 ALERT type 3 Indicator that the structure quality may be low 0 ALERT type 4 Improvement, methodology, query or suggestion 0 ALERT type 5 Informative message, check

Comment top

The title compound was prepared in order to extend our study on D-H···A hydrogen bonding (D = N, O, or C; A = N, O or Cl) in amine–chloranilic acid 1:1 and 2:1 systems (Gotoh et al., 2006).

The asymmetric unit contains one quinoxaline molecule and two half chloranilic acid molecules. No acid-base interaction involving a proton transfer is observed between the quinoxaline and the chloranilic acid. In the crystal structure, the quinoxaline and the chloranilic acid are linked alternately through two kinds of O—H···N hydrogen bonds to form a zigzag chain running along the [201] direction (Fig. 1). Similar chain structures have been observed in the related compounds containing the pyrazine unit, i.e., pyrazine–chloranilic acid (1/1) (Ishida & Kashino, 1999), phenazine–chloranilic acid (1/1) (Horiuchi et al., 2005; Gotoh et al., 2007) and tetramethylpyrazine–chloranilic acid (1/1) (Prager et al., 2005, 2006). The chains are stacked along the a axis, forming a layer extending parallel to the (010) plane (Fig. 2). The layers are further linked by C—H···O hydrogen bonds.

Related literature top

For related literature, see: Gotoh et al. (2006, 2007); Horiuchi et al. (2005); Ishida & Kashino (1999); Prager et al. (2005, 2006).

Experimental top

Single crystals were obtained by slow evaporation from a methanol solution of chloranilic acid (99 mg) and quinoxaline (63 mg).

Refinement top

O-bound H atoms were found in a difference Fourier map and refined isotropically (refined distances given in Table 1). C-bound H atoms were positioned geometrically (C—H = 0.95 Å) and refined as riding, with Uiso(H) = 1.2Ueq(C).

Structure description top

The title compound was prepared in order to extend our study on D-H···A hydrogen bonding (D = N, O, or C; A = N, O or Cl) in amine–chloranilic acid 1:1 and 2:1 systems (Gotoh et al., 2006).

The asymmetric unit contains one quinoxaline molecule and two half chloranilic acid molecules. No acid-base interaction involving a proton transfer is observed between the quinoxaline and the chloranilic acid. In the crystal structure, the quinoxaline and the chloranilic acid are linked alternately through two kinds of O—H···N hydrogen bonds to form a zigzag chain running along the [201] direction (Fig. 1). Similar chain structures have been observed in the related compounds containing the pyrazine unit, i.e., pyrazine–chloranilic acid (1/1) (Ishida & Kashino, 1999), phenazine–chloranilic acid (1/1) (Horiuchi et al., 2005; Gotoh et al., 2007) and tetramethylpyrazine–chloranilic acid (1/1) (Prager et al., 2005, 2006). The chains are stacked along the a axis, forming a layer extending parallel to the (010) plane (Fig. 2). The layers are further linked by C—H···O hydrogen bonds.

For related literature, see: Gotoh et al. (2006, 2007); Horiuchi et al. (2005); Ishida & Kashino (1999); Prager et al. (2005, 2006).

Computing details top

Data collection: PROCESS-AUTO (Rigaku/MSC, 2004); cell refinement: PROCESS-AUTO (Rigaku/MSC, 2004); data reduction: CrystalStructure (Rigaku/MSC, 2004); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: CrystalStructure (Rigaku/MSC, 2004).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, with 70% probability displacement ellipsoids. The dashed lines indicate hydrogen bonds (symmetry codes as Table 1).
[Figure 2] Fig. 2. A partial packing diagram of the title compound, viewed down the a axis. The dashed lines indicate hydrogen bonds.
Quinoxaline–chloranilic acid (1/1) top
Crystal data top
C8H6N2·C6H2Cl2O4Z = 2
Mr = 339.13F(000) = 344.00
Triclinic, P1Dx = 1.707 Mg m3
Hall symbol: -P 1Mo Kα radiation, λ = 0.71075 Å
a = 3.7963 (3) ÅCell parameters from 6043 reflections
b = 7.7760 (7) Åθ = 3.1–27.5°
c = 22.4830 (14) ŵ = 0.51 mm1
α = 93.444 (3)°T = 95 K
β = 94.338 (3)°Plate, orange
γ = 92.322 (4)°0.48 × 0.43 × 0.10 mm
V = 659.92 (9) Å3
Data collection top
Rigaku R-AXIS RAPID
diffractometer
2314 reflections with I > 2σ(I)
Detector resolution: 10.00 pixels mm-1Rint = 0.066
ω scansθmax = 27.5°, θmin = 3.1°
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)
h = 44
Tmin = 0.776, Tmax = 0.950k = 1010
6457 measured reflectionsl = 2829
2974 independent reflections
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.044Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.102H atoms treated by a mixture of independent and constrained refinement
S = 1.00 w = 1/[σ2(Fo2) + (0.0337P)2]
where P = (Fo2 + 2Fc2)/3
2974 reflections(Δ/σ)max = 0.001
207 parametersΔρmax = 0.41 e Å3
0 restraintsΔρmin = 0.66 e Å3
Crystal data top
C8H6N2·C6H2Cl2O4γ = 92.322 (4)°
Mr = 339.13V = 659.92 (9) Å3
Triclinic, P1Z = 2
a = 3.7963 (3) ÅMo Kα radiation
b = 7.7760 (7) ŵ = 0.51 mm1
c = 22.4830 (14) ÅT = 95 K
α = 93.444 (3)°0.48 × 0.43 × 0.10 mm
β = 94.338 (3)°
Data collection top
Rigaku R-AXIS RAPID
diffractometer
2974 independent reflections
Absorption correction: multi-scan
(ABSCOR; Higashi, 1995)
2314 reflections with I > 2σ(I)
Tmin = 0.776, Tmax = 0.950Rint = 0.066
6457 measured reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0440 restraints
wR(F2) = 0.102H atoms treated by a mixture of independent and constrained refinement
S = 1.00Δρmax = 0.41 e Å3
2974 reflectionsΔρmin = 0.66 e Å3
207 parameters
Special details top

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top
xyzUiso*/Ueq
Cl10.71248 (15)0.13239 (7)0.05495 (2)0.01197 (14)
Cl20.30454 (15)0.15380 (7)0.54442 (2)0.01202 (14)
O11.0774 (4)0.4141 (2)0.11448 (6)0.0123 (3)
O20.6729 (4)0.2726 (2)0.06970 (6)0.0123 (4)
O30.0320 (4)0.4309 (2)0.61393 (6)0.0124 (4)
O40.3146 (4)0.2776 (2)0.42231 (6)0.0120 (4)
N10.6017 (5)0.3172 (2)0.18738 (7)0.0092 (4)
N20.4432 (5)0.3263 (2)0.30786 (7)0.0088 (4)
C11.0353 (6)0.4490 (3)0.06137 (8)0.0074 (4)
C20.8644 (6)0.3303 (3)0.02377 (8)0.0077 (4)
C30.8287 (6)0.3768 (3)0.03447 (8)0.0084 (4)
C40.0157 (6)0.4576 (3)0.56123 (8)0.0083 (4)
C50.1411 (6)0.3397 (3)0.51849 (8)0.0080 (4)
C60.1634 (6)0.3792 (3)0.46131 (8)0.0082 (4)
C70.4737 (6)0.4533 (3)0.21394 (9)0.0105 (4)
H70.43380.55200.19180.013*
C80.3932 (6)0.4577 (3)0.27438 (9)0.0100 (4)
H80.29970.55920.29140.012*
C90.5850 (6)0.1841 (3)0.28184 (8)0.0077 (4)
C100.6588 (6)0.0413 (3)0.31613 (9)0.0114 (4)
H100.61120.04460.35710.014*
C110.7991 (6)0.1021 (3)0.29023 (9)0.0129 (5)
H110.85000.19770.31330.015*
C120.8687 (6)0.1080 (3)0.22886 (9)0.0132 (5)
H120.96280.20850.21120.016*
C130.8022 (6)0.0286 (3)0.19491 (9)0.0111 (4)
H130.85010.02280.15400.013*
C140.6621 (6)0.1784 (3)0.22068 (8)0.0082 (4)
H20.669 (8)0.311 (4)0.1043 (12)0.018 (7)*
H40.338 (14)0.312 (7)0.388 (2)0.110 (19)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Cl10.0151 (3)0.0100 (3)0.0103 (3)0.0034 (2)0.00261 (18)0.00259 (17)
Cl20.0171 (3)0.0093 (3)0.0107 (3)0.0050 (2)0.00351 (18)0.00301 (17)
O10.0168 (9)0.0148 (9)0.0057 (7)0.0014 (7)0.0041 (6)0.0002 (5)
O20.0203 (10)0.0120 (9)0.0047 (7)0.0050 (7)0.0051 (6)0.0007 (5)
O30.0185 (9)0.0134 (9)0.0063 (7)0.0027 (7)0.0049 (6)0.0020 (5)
O40.0194 (9)0.0112 (9)0.0066 (7)0.0054 (7)0.0056 (6)0.0000 (5)
N10.0077 (10)0.0131 (10)0.0068 (8)0.0019 (8)0.0021 (6)0.0004 (6)
N20.0097 (10)0.0097 (10)0.0073 (8)0.0009 (7)0.0024 (6)0.0003 (6)
C10.0052 (11)0.0109 (11)0.0063 (9)0.0005 (8)0.0009 (7)0.0017 (7)
C20.0085 (11)0.0069 (11)0.0077 (9)0.0011 (8)0.0017 (7)0.0001 (7)
C30.0071 (11)0.0095 (11)0.0088 (10)0.0012 (9)0.0011 (7)0.0031 (7)
C40.0074 (11)0.0096 (11)0.0075 (9)0.0020 (8)0.0011 (7)0.0008 (7)
C50.0095 (11)0.0062 (11)0.0085 (10)0.0018 (8)0.0002 (7)0.0014 (7)
C60.0084 (11)0.0083 (11)0.0076 (10)0.0009 (8)0.0024 (7)0.0018 (7)
C70.0086 (11)0.0106 (11)0.0126 (10)0.0008 (9)0.0011 (8)0.0025 (7)
C80.0100 (11)0.0086 (11)0.0115 (10)0.0009 (9)0.0022 (8)0.0003 (7)
C90.0071 (11)0.0099 (11)0.0060 (9)0.0011 (8)0.0008 (7)0.0005 (7)
C100.0135 (12)0.0113 (12)0.0099 (10)0.0016 (9)0.0026 (7)0.0016 (7)
C110.0133 (12)0.0096 (12)0.0161 (11)0.0002 (9)0.0013 (8)0.0027 (8)
C120.0108 (12)0.0114 (12)0.0172 (11)0.0008 (9)0.0043 (8)0.0039 (8)
C130.0072 (11)0.0140 (12)0.0115 (10)0.0018 (9)0.0028 (7)0.0034 (7)
C140.0053 (11)0.0107 (12)0.0084 (10)0.0019 (8)0.0015 (7)0.0013 (7)
Geometric parameters (Å, º) top
Cl1—C21.711 (2)C4—C6ii1.508 (3)
Cl2—C51.713 (2)C5—C61.348 (3)
O1—C11.232 (2)C6—C4ii1.508 (3)
O2—C31.321 (2)C7—C81.414 (3)
O2—H20.82 (3)C7—H70.9500
O3—C41.221 (2)C8—H80.9500
O4—C61.324 (2)C9—C101.415 (3)
O4—H40.85 (5)C9—C141.426 (3)
N1—C71.313 (3)C10—C111.372 (3)
N1—C141.367 (3)C10—H100.9500
N2—C81.316 (3)C11—C121.423 (3)
N2—C91.368 (3)C11—H110.9500
C1—C21.455 (3)C12—C131.365 (3)
C1—C3i1.505 (3)C12—H120.9500
C2—C31.356 (3)C13—C141.411 (3)
C3—C1i1.505 (3)C13—H130.9500
C4—C51.464 (3)
C3—O2—H2114 (2)N1—C7—H7118.9
C6—O4—H4119 (4)C8—C7—H7118.9
C7—N1—C14117.54 (16)N2—C8—C7122.4 (2)
C8—N2—C9116.86 (17)N2—C8—H8118.8
O1—C1—C2123.3 (2)C7—C8—H8118.8
O1—C1—C3i117.76 (19)N2—C9—C10119.65 (17)
C2—C1—C3i118.89 (17)N2—C9—C14120.90 (18)
C3—C2—C1120.2 (2)C10—C9—C14119.45 (19)
C3—C2—Cl1121.46 (17)C11—C10—C9119.96 (18)
C1—C2—Cl1118.33 (15)C11—C10—H10120.0
O2—C3—C2121.7 (2)C9—C10—H10120.0
O2—C3—C1i117.37 (17)C10—C11—C12120.2 (2)
C2—C3—C1i120.91 (19)C10—C11—H11119.9
O3—C4—C5123.53 (19)C12—C11—H11119.9
O3—C4—C6ii118.54 (18)C13—C12—C11121.0 (2)
C5—C4—C6ii117.93 (17)C13—C12—H12119.5
C6—C5—C4120.83 (19)C11—C12—H12119.5
C6—C5—Cl2121.59 (17)C12—C13—C14119.89 (18)
C4—C5—Cl2117.55 (14)C12—C13—H13120.1
O4—C6—C5122.0 (2)C14—C13—H13120.1
O4—C6—C4ii116.79 (17)N1—C14—C13120.32 (17)
C5—C6—C4ii121.19 (18)N1—C14—C9120.20 (19)
N1—C7—C8122.10 (19)C13—C14—C9119.48 (19)
O1—C1—C2—C3179.6 (2)C9—N2—C8—C71.3 (3)
C3i—C1—C2—C30.1 (3)N1—C7—C8—N20.4 (4)
O1—C1—C2—Cl10.3 (3)C8—N2—C9—C10177.4 (2)
C3i—C1—C2—Cl1179.79 (16)C8—N2—C9—C142.1 (3)
C1—C2—C3—O2179.54 (18)N2—C9—C10—C11179.6 (2)
Cl1—C2—C3—O20.6 (3)C14—C9—C10—C110.8 (3)
C1—C2—C3—C1i0.1 (4)C9—C10—C11—C120.4 (4)
Cl1—C2—C3—C1i179.78 (16)C10—C11—C12—C130.9 (4)
O3—C4—C5—C6177.5 (2)C11—C12—C13—C140.0 (3)
C6ii—C4—C5—C62.3 (4)C7—N1—C14—C13179.5 (2)
O3—C4—C5—Cl20.8 (3)C7—N1—C14—C90.3 (3)
C6ii—C4—C5—Cl2179.44 (16)C12—C13—C14—N1178.6 (2)
C4—C5—C6—O4177.7 (2)C12—C13—C14—C91.2 (3)
Cl2—C5—C6—O40.5 (3)N2—C9—C14—N11.3 (3)
C4—C5—C6—C4ii2.3 (4)C10—C9—C14—N1178.2 (2)
Cl2—C5—C6—C4ii179.43 (17)N2—C9—C14—C13178.8 (2)
C14—N1—C7—C81.1 (3)C10—C9—C14—C131.6 (3)
Symmetry codes: (i) x+2, y+1, z; (ii) x, y+1, z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···N10.82 (3)1.90 (3)2.683 (2)159 (3)
O2—H2···O1i0.82 (3)2.30 (3)2.687 (2)110 (2)
O4—H4···N20.84 (5)1.89 (5)2.701 (2)163 (5)
O4—H4···O3ii0.84 (5)2.35 (5)2.691 (2)105 (4)
C7—H7···O1iii0.952.543.191 (3)126
C8—H8···O3ii0.952.433.048 (3)123
C10—H10···Cl2iv0.952.783.560 (2)140
C11—H11···O3iv0.952.593.538 (3)173
Symmetry codes: (i) x+2, y+1, z; (ii) x, y+1, z+1; (iii) x+1, y+1, z; (iv) x+1, y, z+1.

Experimental details

Crystal data
Chemical formulaC8H6N2·C6H2Cl2O4
Mr339.13
Crystal system, space groupTriclinic, P1
Temperature (K)95
a, b, c (Å)3.7963 (3), 7.7760 (7), 22.4830 (14)
α, β, γ (°)93.444 (3), 94.338 (3), 92.322 (4)
V3)659.92 (9)
Z2
Radiation typeMo Kα
µ (mm1)0.51
Crystal size (mm)0.48 × 0.43 × 0.10
Data collection
DiffractometerRigaku R-AXIS RAPID
Absorption correctionMulti-scan
(ABSCOR; Higashi, 1995)
Tmin, Tmax0.776, 0.950
No. of measured, independent and
observed [I > 2σ(I)] reflections
6457, 2974, 2314
Rint0.066
(sin θ/λ)max1)0.649
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.044, 0.102, 1.00
No. of reflections2974
No. of parameters207
H-atom treatmentH atoms treated by a mixture of independent and constrained refinement
Δρmax, Δρmin (e Å3)0.41, 0.66

Computer programs: PROCESS-AUTO (Rigaku/MSC, 2004), CrystalStructure (Rigaku/MSC, 2004), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), ORTEP-3 (Farrugia, 1997).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O2—H2···N10.82 (3)1.90 (3)2.683 (2)159 (3)
O2—H2···O1i0.82 (3)2.30 (3)2.687 (2)110 (2)
O4—H4···N20.84 (5)1.89 (5)2.701 (2)163 (5)
O4—H4···O3ii0.84 (5)2.35 (5)2.691 (2)105 (4)
C7—H7···O1iii0.952.543.191 (3)126
C8—H8···O3ii0.952.433.048 (3)123
C10—H10···Cl2iv0.952.783.560 (2)140
C11—H11···O3iv0.952.593.538 (3)173
Symmetry codes: (i) x+2, y+1, z; (ii) x, y+1, z+1; (iii) x+1, y+1, z; (iv) x+1, y, z+1.
 

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