Supporting information
Crystallographic Information File (CIF) https://doi.org/10.1107/S1600536807023288/at2290sup1.cif | |
Structure factor file (CIF format) https://doi.org/10.1107/S1600536807023288/at2290Isup2.hkl |
CCDC reference: 651511
A suspension of 1,2-bis(4-bromophenyl)ethane-1,2-dione (0.8 mmol) and benzene-1,2-diamine (1.0 mmol) in acetic acid (3 ml) was heated to reflux for 0.5 h. The mixture was then poured into ice water and a white precipitate was formed. The mixture was neutralized using saturated NaHCO3 solution. The resulting precipitate was filtered off, washed with water, dried and purified by recrystallization using a mixture of ethyl acetate and petroleum ether (1:5), giving the target product as white needle crystals in 93.3% yield. Crystals of (I) suitable for single-crystal X-ray analysis were grown by slow evaporation of a solution in chloroform/ethanol (1:1). Spectroscopic analysis: 1H NMR (CDCl3, δ, p.p.m.): 8.18–8.16 (m, 2H), 7.82–7.80 (m, 2H), 7.52–7.51 (m, 4H), 7.42–7.41 (m, 4H). EI—MS (m/z): 440.7 [M+1]+.
All H atoms were positioned geometrically and refined as riding (C—H = 0.93%A) and allowed to ride on their parent atoms, with Uiso(H) = 1.2Ueq(parent).
Functionalized quinoxalines represent an important class of nitrogen-containing heterocycle. While rarely described in nature, synthetic quinoxalines are well known in the pharmaceutical industry and have been shown to possess a broad spectrum of biological activities including antiviral, antibacterial and as kinase inhibitors (Loriga et al., 1997; Seitz et al., 2002; He et al., 2003). Recently, we have reported an analogic structure of quinoxaline derivative, namely, 2,3-bis(4-cholrophenyl)quinoxaline. Now we have synthesized a new quinoxaline derivative, 2,3-bis(4-bromophenyl)quinoxaline, (I). We present its crystal structure here.
In the molecular structure of (I) in Fig. 1, the two benzene rings attached to the quinoxaline ring are inclined at an angle of 58.7 (2)°. The quinoxaline ring is approximately planar, with an r. m. s. deviation of 0.033°. The two benzene rings make dihedral angles of 43.7 (2) and 53.9 (2)°, respectively, with the planar quinoxaline ring. The C10—C15 and C9—C173 bond lengths between the benzene rings and the quionxaline ring, [1.499 (5) and 1.480 (5) Å, respectively] are slightly shorter than the general C—C single bond length (Kennedy et al., 2004) as a consequence of the conjugate structure among the aromatic rings.
For related literature, see: He et al. (2003); Kennedy et al. (2004); Loriga et al. (1997); Seitz et al. (2002).
Data collection: SMART (Bruker, 1997); cell refinement: SMART; data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: SHELXTL (Bruker, 1997); software used to prepare material for publication: SHELXTL.
Fig. 1. View of the molecule of (I) showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 35% probability level. |
C20H12Br2N2 | Z = 4 |
Mr = 440.14 | F(000) = 864 |
Monoclinic, P21/n | Dx = 1.756 Mg m−3 |
Hall symbol: -P 2yn | Melting point: 461 K |
a = 13.5822 (17) Å | Mo Kα radiation, λ = 0.71073 Å |
b = 7.6918 (13) Å | µ = 4.87 mm−1 |
c = 16.482 (3) Å | T = 298 K |
β = 104.752 (9)° | Plate, colourless |
V = 1665.1 (5) Å3 | 0.35 × 0.26 × 0.18 mm |
Bruker SMART CCD area detector diffractometer | 2922 independent reflections |
Radiation source: fine-focus sealed tube | 2132 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.039 |
φ and ω scans | θmax = 25.0°, θmin = 2.3° |
Absorption correction: multi-scan SADABS (Bruker, 1997) | h = −16→16 |
Tmin = 0.281, Tmax = 0.474 | k = −9→7 |
9727 measured reflections | l = −19→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)] = 0.047 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.139 | H-atom parameters constrained |
S = 0.96 | w = 1/[σ2(Fo2) + (0.1P)2] where P = (Fo2 + 2Fc2)/3 |
2922 reflections | (Δ/σ)max < 0.001 |
217 parameters | Δρmax = 0.43 e Å−3 |
0 restraints | Δρmin = −1.15 e Å−3 |
C20H12Br2N2 | V = 1665.1 (5) Å3 |
Mr = 440.14 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 13.5822 (17) Å | µ = 4.87 mm−1 |
b = 7.6918 (13) Å | T = 298 K |
c = 16.482 (3) Å | 0.35 × 0.26 × 0.18 mm |
β = 104.752 (9)° |
Bruker SMART CCD area detector diffractometer | 2922 independent reflections |
Absorption correction: multi-scan SADABS (Bruker, 1997) | 2132 reflections with I > 2σ(I) |
Tmin = 0.281, Tmax = 0.474 | Rint = 0.039 |
9727 measured reflections |
R[F2 > 2σ(F2)] = 0.047 | 0 restraints |
wR(F2) = 0.139 | H-atom parameters constrained |
S = 0.96 | Δρmax = 0.43 e Å−3 |
2922 reflections | Δρmin = −1.15 e Å−3 |
217 parameters |
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 | ||
Br1 | 0.08495 (3) | 0.95152 (7) | 0.11599 (3) | 0.0555 (2) | |
Br2 | −0.18098 (4) | 1.54598 (9) | −0.17208 (3) | 0.0734 (3) | |
N2 | −0.3517 (2) | 1.0631 (4) | 0.1736 (2) | 0.0390 (8) | |
N1 | −0.4070 (2) | 1.2803 (5) | 0.0336 (2) | 0.0370 (8) | |
C20 | −0.4787 (3) | 1.1927 (5) | 0.0618 (3) | 0.0356 (9) | |
C19 | −0.0077 (3) | 1.0131 (5) | 0.1798 (3) | 0.0372 (10) | |
C18 | −0.0427 (3) | 1.0550 (6) | 0.3121 (3) | 0.0477 (12) | |
H18A | −0.0212 | 1.0561 | 0.3703 | 0.057* | |
C173 | −0.2364 (3) | 1.3751 (5) | 0.0492 (3) | 0.0345 (9) | |
C16 | −0.1655 (3) | 1.4680 (5) | 0.1092 (3) | 0.0410 (10) | |
H16A | −0.1620 | 1.4532 | 0.1659 | 0.049* | |
C15 | −0.1746 (3) | 1.0998 (5) | 0.1855 (3) | 0.0342 (9) | |
C14 | −0.1739 (3) | 1.5134 (6) | −0.0578 (3) | 0.0415 (10) | |
C13 | −0.4511 (3) | 1.0908 (5) | 0.1337 (3) | 0.0363 (10) | |
C12 | −0.1065 (3) | 1.0592 (5) | 0.1387 (3) | 0.0362 (10) | |
H12A | −0.1267 | 1.0629 | 0.0804 | 0.043* | |
C11 | −0.5826 (3) | 1.2121 (6) | 0.0204 (3) | 0.0473 (11) | |
H11A | −0.6017 | 1.2783 | −0.0283 | 0.057* | |
C10 | −0.2833 (3) | 1.1429 (5) | 0.1438 (2) | 0.0338 (9) | |
C9 | −0.3111 (3) | 1.2620 (5) | 0.0751 (2) | 0.0338 (9) | |
C8 | −0.6272 (3) | 1.0345 (6) | 0.1236 (3) | 0.0527 (13) | |
H8A | −0.6779 | 0.9822 | 0.1438 | 0.063* | |
C7 | −0.1039 (3) | 1.6059 (6) | 0.0012 (3) | 0.0479 (11) | |
H7A | −0.0598 | 1.6832 | −0.0150 | 0.058* | |
C6 | −0.5277 (3) | 1.0109 (6) | 0.1654 (3) | 0.0465 (11) | |
H6A | −0.5104 | 0.9435 | 0.2138 | 0.056* | |
C5 | −0.1415 (3) | 1.0988 (6) | 0.2727 (3) | 0.0424 (10) | |
H5A | −0.1866 | 1.1280 | 0.3046 | 0.051* | |
C4 | −0.6542 (3) | 1.1349 (7) | 0.0514 (3) | 0.0529 (12) | |
H4A | −0.7226 | 1.1492 | 0.0241 | 0.063* | |
C3 | 0.0247 (3) | 1.0097 (6) | 0.2658 (3) | 0.0437 (11) | |
H3A | 0.0910 | 0.9772 | 0.2924 | 0.052* | |
C2 | −0.2412 (3) | 1.4004 (6) | −0.0348 (3) | 0.0383 (10) | |
H2B | −0.2895 | 1.3415 | −0.0757 | 0.046* | |
C1 | −0.1001 (3) | 1.5823 (6) | 0.0844 (3) | 0.0444 (11) | |
H1B | −0.0528 | 1.6441 | 0.1249 | 0.053* |
U11 | U22 | U33 | U12 | U13 | U23 | |
Br1 | 0.0302 (3) | 0.0757 (4) | 0.0622 (4) | 0.0013 (2) | 0.0149 (2) | −0.0061 (3) |
Br2 | 0.0542 (4) | 0.1241 (6) | 0.0448 (4) | −0.0103 (3) | 0.0177 (3) | 0.0214 (3) |
N2 | 0.0288 (18) | 0.051 (2) | 0.037 (2) | −0.0007 (15) | 0.0093 (15) | 0.0031 (16) |
N1 | 0.0288 (16) | 0.048 (2) | 0.0335 (19) | 0.0014 (15) | 0.0074 (14) | 0.0005 (16) |
C20 | 0.0237 (18) | 0.043 (2) | 0.039 (2) | −0.0001 (17) | 0.0067 (17) | −0.0026 (19) |
C19 | 0.026 (2) | 0.035 (2) | 0.050 (3) | −0.0003 (16) | 0.0097 (19) | 0.0027 (19) |
C18 | 0.038 (2) | 0.068 (3) | 0.034 (2) | 0.005 (2) | 0.002 (2) | 0.008 (2) |
C173 | 0.0228 (18) | 0.044 (2) | 0.037 (2) | 0.0026 (17) | 0.0079 (17) | 0.0021 (19) |
C16 | 0.035 (2) | 0.048 (3) | 0.038 (2) | 0.0028 (19) | 0.006 (2) | 0.001 (2) |
C15 | 0.0252 (19) | 0.037 (2) | 0.038 (2) | −0.0039 (16) | 0.0042 (17) | 0.0057 (18) |
C14 | 0.029 (2) | 0.059 (3) | 0.039 (2) | 0.0045 (19) | 0.0119 (19) | 0.009 (2) |
C13 | 0.027 (2) | 0.043 (2) | 0.040 (2) | −0.0046 (17) | 0.0112 (18) | −0.0037 (19) |
C12 | 0.031 (2) | 0.044 (3) | 0.033 (2) | −0.0036 (17) | 0.0061 (18) | −0.0017 (18) |
C11 | 0.029 (2) | 0.060 (3) | 0.051 (3) | 0.006 (2) | 0.0047 (19) | 0.006 (2) |
C10 | 0.0263 (18) | 0.043 (2) | 0.031 (2) | 0.0009 (17) | 0.0067 (16) | 0.0005 (19) |
C9 | 0.0281 (19) | 0.042 (2) | 0.032 (2) | −0.0017 (17) | 0.0084 (16) | −0.0027 (18) |
C8 | 0.029 (2) | 0.074 (3) | 0.058 (3) | −0.009 (2) | 0.017 (2) | −0.006 (3) |
C7 | 0.030 (2) | 0.053 (3) | 0.060 (3) | −0.003 (2) | 0.012 (2) | 0.011 (2) |
C6 | 0.033 (2) | 0.062 (3) | 0.047 (3) | −0.013 (2) | 0.014 (2) | 0.005 (2) |
C5 | 0.033 (2) | 0.059 (3) | 0.036 (2) | −0.001 (2) | 0.0100 (19) | 0.006 (2) |
C4 | 0.022 (2) | 0.072 (3) | 0.061 (3) | −0.001 (2) | 0.005 (2) | −0.010 (3) |
C3 | 0.028 (2) | 0.048 (3) | 0.048 (3) | 0.0003 (18) | −0.002 (2) | 0.004 (2) |
C2 | 0.028 (2) | 0.051 (2) | 0.036 (2) | −0.0021 (18) | 0.0082 (17) | 0.002 (2) |
C1 | 0.031 (2) | 0.052 (3) | 0.047 (3) | −0.0066 (19) | 0.0054 (19) | 0.001 (2) |
Br1—C19 | 1.894 (4) | C15—C10 | 1.499 (5) |
Br2—C14 | 1.879 (4) | C14—C7 | 1.373 (6) |
N2—C10 | 1.309 (5) | C14—C2 | 1.382 (6) |
N2—C13 | 1.359 (5) | C13—C6 | 1.418 (6) |
N1—C9 | 1.316 (4) | C12—H12A | 0.9300 |
N1—C20 | 1.360 (5) | C11—C4 | 1.346 (6) |
C20—C13 | 1.391 (6) | C11—H11A | 0.9300 |
C20—C11 | 1.410 (5) | C10—C9 | 1.431 (5) |
C19—C3 | 1.374 (6) | C8—C6 | 1.363 (6) |
C19—C12 | 1.387 (6) | C8—C4 | 1.387 (7) |
C18—C5 | 1.376 (6) | C8—H8A | 0.9300 |
C18—C3 | 1.376 (7) | C7—C1 | 1.372 (6) |
C18—H18A | 0.9300 | C7—H7A | 0.9300 |
C173—C16 | 1.390 (6) | C6—H6A | 0.9300 |
C173—C2 | 1.383 (6) | C5—H5A | 0.9300 |
C173—C9 | 1.480 (5) | C4—H4A | 0.9300 |
C16—C1 | 1.383 (6) | C3—H3A | 0.9300 |
C16—H16A | 0.9300 | C2—H2B | 0.9300 |
C15—C12 | 1.384 (6) | C1—H1B | 0.9300 |
C15—C5 | 1.391 (6) | ||
C10—N2—C13 | 117.3 (3) | C20—C11—H11A | 120.0 |
C9—N1—C20 | 118.0 (3) | N2—C10—C9 | 121.8 (3) |
N1—C20—C13 | 120.6 (3) | N2—C10—C15 | 115.8 (3) |
N1—C20—C11 | 119.9 (4) | C9—C10—C15 | 122.4 (3) |
C13—C20—C11 | 119.4 (4) | N1—C9—C10 | 120.5 (3) |
C3—C19—C12 | 121.7 (4) | N1—C9—C173 | 116.6 (3) |
C3—C19—Br1 | 119.0 (3) | C10—C9—C173 | 122.9 (3) |
C12—C19—Br1 | 119.3 (3) | C6—C8—C4 | 121.3 (4) |
C5—C18—C3 | 120.5 (4) | C6—C8—H8A | 119.4 |
C5—C18—H18A | 119.8 | C4—C8—H8A | 119.4 |
C3—C18—H18A | 119.8 | C1—C7—C14 | 118.8 (4) |
C16—C173—C2 | 119.2 (4) | C1—C7—H7A | 120.6 |
C16—C173—C9 | 119.9 (4) | C14—C7—H7A | 120.6 |
C2—C173—C9 | 120.7 (3) | C8—C6—C13 | 118.8 (4) |
C173—C16—C1 | 119.8 (4) | C8—C6—H6A | 120.6 |
C173—C16—H16A | 120.1 | C13—C6—H6A | 120.6 |
C1—C16—H16A | 120.1 | C18—C5—C15 | 120.5 (4) |
C12—C15—C5 | 119.3 (4) | C18—C5—H5A | 119.7 |
C12—C15—C10 | 121.0 (4) | C15—C5—H5A | 119.7 |
C5—C15—C10 | 119.7 (4) | C11—C4—C8 | 120.8 (4) |
C7—C14—C2 | 121.3 (4) | C11—C4—H4A | 119.6 |
C7—C14—Br2 | 119.3 (3) | C8—C4—H4A | 119.6 |
C2—C14—Br2 | 119.3 (3) | C19—C3—C18 | 118.9 (4) |
N2—C13—C20 | 121.3 (3) | C19—C3—H3A | 120.5 |
N2—C13—C6 | 119.1 (4) | C18—C3—H3A | 120.5 |
C20—C13—C6 | 119.6 (4) | C14—C2—C173 | 119.8 (4) |
C19—C12—C15 | 119.1 (4) | C14—C2—H2B | 120.1 |
C19—C12—H12A | 120.5 | C173—C2—H2B | 120.1 |
C15—C12—H12A | 120.5 | C7—C1—C16 | 121.1 (4) |
C4—C11—C20 | 120.0 (4) | C7—C1—H1B | 119.5 |
C4—C11—H11A | 120.0 | C16—C1—H1B | 119.5 |
C9—N1—C20—C13 | 1.7 (6) | N2—C10—C9—C173 | 169.7 (4) |
C9—N1—C20—C11 | 178.4 (4) | C15—C10—C9—C173 | −11.1 (6) |
C2—C173—C16—C1 | −0.8 (6) | C16—C173—C9—N1 | 130.9 (4) |
C9—C173—C16—C1 | −175.8 (4) | C2—C173—C9—N1 | −44.1 (5) |
C10—N2—C13—C20 | 3.2 (6) | C16—C173—C9—C10 | −46.5 (6) |
C10—N2—C13—C6 | −178.2 (4) | C2—C173—C9—C10 | 138.5 (4) |
N1—C20—C13—N2 | −5.9 (6) | C2—C14—C7—C1 | 1.2 (7) |
C11—C20—C13—N2 | 177.4 (4) | Br2—C14—C7—C1 | 179.4 (3) |
N1—C20—C13—C6 | 175.4 (4) | C4—C8—C6—C13 | −0.2 (7) |
C11—C20—C13—C6 | −1.3 (6) | N2—C13—C6—C8 | −177.9 (4) |
C3—C19—C12—C15 | −1.2 (6) | C20—C13—C6—C8 | 0.8 (7) |
Br1—C19—C12—C15 | 178.4 (3) | C3—C18—C5—C15 | −0.7 (7) |
C5—C15—C12—C19 | 2.1 (6) | C12—C15—C5—C18 | −1.1 (6) |
C10—C15—C12—C19 | −177.3 (4) | C10—C15—C5—C18 | 178.3 (4) |
N1—C20—C11—C4 | −175.5 (4) | C20—C11—C4—C8 | −0.6 (7) |
C13—C20—C11—C4 | 1.2 (7) | C6—C8—C4—C11 | 0.1 (8) |
C13—N2—C10—C9 | 3.3 (6) | C12—C19—C3—C18 | −0.7 (6) |
C13—N2—C10—C15 | −175.9 (3) | Br1—C19—C3—C18 | 179.8 (3) |
C12—C15—C10—N2 | 132.3 (4) | C5—C18—C3—C19 | 1.6 (7) |
C5—C15—C10—N2 | −47.2 (5) | C7—C14—C2—C173 | −2.0 (6) |
C12—C15—C10—C9 | −47.0 (6) | Br2—C14—C2—C173 | 179.8 (3) |
C5—C15—C10—C9 | 133.6 (4) | C16—C173—C2—C14 | 1.8 (6) |
C20—N1—C9—C10 | 4.7 (6) | C9—C173—C2—C14 | 176.7 (4) |
C20—N1—C9—C173 | −172.8 (4) | C14—C7—C1—C16 | −0.2 (7) |
N2—C10—C9—N1 | −7.6 (6) | C173—C16—C1—C7 | 0.0 (7) |
C15—C10—C9—N1 | 171.6 (4) |
Experimental details
Crystal data | |
Chemical formula | C20H12Br2N2 |
Mr | 440.14 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 298 |
a, b, c (Å) | 13.5822 (17), 7.6918 (13), 16.482 (3) |
β (°) | 104.752 (9) |
V (Å3) | 1665.1 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 4.87 |
Crystal size (mm) | 0.35 × 0.26 × 0.18 |
Data collection | |
Diffractometer | Bruker SMART CCD area detector |
Absorption correction | Multi-scan SADABS (Bruker, 1997) |
Tmin, Tmax | 0.281, 0.474 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 9727, 2922, 2132 |
Rint | 0.039 |
(sin θ/λ)max (Å−1) | 0.594 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.047, 0.139, 0.96 |
No. of reflections | 2922 |
No. of parameters | 217 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.43, −1.15 |
Computer programs: SMART (Bruker, 1997), SMART, SAINT (Bruker, 1997), SHELXS97 (Sheldrick, 1997), SHELXL97 (Sheldrick, 1997), SHELXTL (Bruker, 1997), SHELXTL.
Br1—C19 | 1.894 (4) | N1—C9 | 1.316 (4) |
Br2—C14 | 1.879 (4) | N1—C20 | 1.360 (5) |
N2—C10 | 1.309 (5) | C173—C9 | 1.480 (5) |
N2—C13 | 1.359 (5) | C15—C10 | 1.499 (5) |
Functionalized quinoxalines represent an important class of nitrogen-containing heterocycle. While rarely described in nature, synthetic quinoxalines are well known in the pharmaceutical industry and have been shown to possess a broad spectrum of biological activities including antiviral, antibacterial and as kinase inhibitors (Loriga et al., 1997; Seitz et al., 2002; He et al., 2003). Recently, we have reported an analogic structure of quinoxaline derivative, namely, 2,3-bis(4-cholrophenyl)quinoxaline. Now we have synthesized a new quinoxaline derivative, 2,3-bis(4-bromophenyl)quinoxaline, (I). We present its crystal structure here.
In the molecular structure of (I) in Fig. 1, the two benzene rings attached to the quinoxaline ring are inclined at an angle of 58.7 (2)°. The quinoxaline ring is approximately planar, with an r. m. s. deviation of 0.033°. The two benzene rings make dihedral angles of 43.7 (2) and 53.9 (2)°, respectively, with the planar quinoxaline ring. The C10—C15 and C9—C173 bond lengths between the benzene rings and the quionxaline ring, [1.499 (5) and 1.480 (5) Å, respectively] are slightly shorter than the general C—C single bond length (Kennedy et al., 2004) as a consequence of the conjugate structure among the aromatic rings.