2,3-Bis(4-bromo­phen­yl)quinoxaline

Abstract

The title compound, C₂₀H₁₂Br₂N₂, was prepared by the reaction of 1-(3-bromo­phen­yl)-2-(4-bromo­phen­yl)ethane-1,2-dione with o-phenyl­enediamine in refluxing ethanol. In the mol­ecule, all bond lengths and angles are within normal ranges. The dihedral angle between the two benzene rings is 34.89 (1)°. The dihedral angles between the benzene rings and the quinoxaline system are 57.23 (1) and 36.75 (1)°. The crystal packing is stabilized by van der Waals forces.

Related literature

For related literature, see: Brock et al. (1999 ▶); Dailey et al. (2001 ▶); Guillon et al. (1998 ▶); Kim et al. (1993 ▶); Patel et al. (2000 ▶); Rong et al. (2006 ▶).

Experimental

Crystal data

• C₂₀H₁₂Br₂N₂

• M _r = 440.14

• Triclinic,

• a = 6.0830 (12) Å

• b = 12.018 (2) Å

• c = 12.323 (3) Å

• α = 105.47 (3)°

• β = 91.89 (3)°

• γ = 97.47 (3)°

• V = 858.7 (3) ų

• Z = 2

• Mo Kα radiation

• μ = 4.72 mm⁻¹

• T = 293 (2) K

• 0.20 × 0.18 × 0.15 mm

Data collection

• Enraf–Nonius CAD-4 diffractometer

• Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.404, T _max = 0.492

• 3338 measured reflections

• 2888 independent reflections

• 1824 reflections with I > 2σ(I)

• R _int = 0.027

• 3 standard reflections every 100 reflections intensity decay: none

Refinement

• R[F ² > 2σ(F ²)] = 0.046

• wR(F ²) = 0.128

• S = 1.06

• 2888 reflections

• 217 parameters

• H-atom parameters constrained

• Δρ_max = 0.56 e Å⁻³

• Δρ_min = −0.74 e Å⁻³

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 Software; data reduction: NRCVAX (Gabe et al., 1989 ▶); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997 ▶); molecular graphics: SHELXTL/PC (Sheldrick, 1990 ▶); software used to prepare material for publication: WinGX (Farrugia, 1999 ▶).

Supplementary Material

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

supplementary crystallographic information

Comment

Quinoxaline derivatives are an important class of nitrogen containing heterocycles and constitute useful intermediates in organic synthesis which have been reported for their applications in the fields of dyes (Brock et al., 1999) and have also been used as building blocks for the synthesis of organic semiconductors (Dailey et al., 2001). Tetrahydroquinoxaline derivatives are important from a therapeutic point of view since promising anti HIV agents (Patel et al., 2000), glucogen receptor antagonists (Guillon et al., 1998) and angiotens in receptor antagonists (Kim et al., 1993) possess this ring system. The title compound (I) was synthesized as part of our study of these ligands. Here we report the crystal structure of (I).

The structure of (I) is represented in Fig. 1. The bond lengths and angles are usual for this type of compound (Rong et al., 2006). The mean planes p1(C1 - C6) and p2 (N1,N2,C7 - C14) make a dihedral angle of 57.23 (1)°. The dihedral angles formed by phenyl ring(C8 –C13) and phenyl ring (C15 - C20) with p1 are 55.48 (1) and 64.80 (1)°, respectively. The dihedral angles between the benzene rings is 34.89 (1)°. The crystal packing (Fig. 2) is stabilized by van der Waals forces.

Experimental

A mixture of 1-(3-bromophenyl)-2-(4-bromophenyl)ethane-1,2-dione (5.77 g, 0.02 mol) and o-phenylene diamine (2.16 g, 0.02 mol) was stirred in refluxing ethanol (30 ml) for 5 h to afford the title compound (3.25 g, yield 74%). Single crystals suitable for X-ray measurements were obtained by recrystallization from THF at room temperature.

Refinement

H atoms were fixed geometrically and allowed to ride on their parent atoms, with N—H and C—H distances of 0.86 and 0.93–0.96 Å, respectively, and with U_iso=1.2–1.5U_eq of the parent atoms.

Figures

Fig. 1.

The molecular structure and atom-labeling scheme for (I), with displacement ellipsoids drawn at the 30% probability level.

Fig. 2.

The crystal packing of (I), viewed down the a axis.

Crystal data

C20H12Br2N2	Z = 2
Mr = 440.14	F000 = 432
Triclinic, P1	Dx = 1.702 Mg m−3
Hall symbol: -P 1	Mo Kα radiation λ = 0.71073 Å
a = 6.0830 (12) Å	Cell parameters from 25 reflections
b = 12.018 (2) Å	θ = 4–14º
c = 12.323 (3) Å	µ = 4.72 mm−1
α = 105.47 (3)º	T = 293 (2) K
β = 91.89 (3)º	Block, yellow
γ = 97.47 (3)º	0.20 × 0.18 × 0.15 mm
V = 858.7 (3) Å3

Data collection

Enraf–Nonius CAD-4 diffractometer	Rint = 0.027
Radiation source: fine-focus sealed tube	θmax = 25.0º
Monochromator: graphite	θmin = 1.7º
T = 293(2) K	h = 0→7
ω scans	k = −14→14
Absorption correction: ψ scan(North et al., 1968)	l = −14→14
Tmin = 0.404, Tmax = 0.492	3 standard reflections
3338 measured reflections	every 100 reflections
2888 independent reflections	intensity decay: none
1824 reflections with I > 2σ(I)

Refinement

Refinement on F2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.046	H-atom parameters constrained
wR(F2) = 0.128	w = 1/[σ2(Fo2) + (0.0589P)2 + 0.7939P] where P = (Fo2 + 2Fc2)/3
S = 1.06	(Δ/σ)max < 0.001
2888 reflections	Δρmax = 0.56 e Å−3
217 parameters	Δρmin = −0.74 e Å−3
Primary atom site location: structure-invariant direct methods	Extinction correction: none

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.47031 (12)	0.83130 (5)	0.45247 (6)	0.0741 (3)
Br2	−0.24223 (11)	0.30938 (6)	−0.14438 (6)	0.0753 (3)
N1	0.7857 (7)	0.2921 (4)	0.3229 (4)	0.0493 (11)
N2	0.4951 (8)	0.1176 (4)	0.1656 (4)	0.0542 (12)
C1	0.3718 (9)	0.4705 (5)	0.3533 (5)	0.0526 (14)
H1B	0.2564	0.4116	0.3532	0.063*
C2	0.3425 (9)	0.5854 (5)	0.3977 (5)	0.0529 (14)
H2B	0.2112	0.6041	0.4297	0.064*
C3	0.5130 (10)	0.6720 (5)	0.3936 (5)	0.0522 (14)
C4	0.7127 (10)	0.6469 (5)	0.3496 (5)	0.0589 (15)
H4A	0.8255	0.7065	0.3480	0.071*
C5	0.7412 (9)	0.5309 (5)	0.3078 (5)	0.0544 (14)
H5A	0.8755	0.5129	0.2789	0.065*
C6	0.5720 (9)	0.4407 (4)	0.3082 (4)	0.0461 (13)
C7	0.6106 (9)	0.3173 (4)	0.2700 (4)	0.0462 (13)
C8	0.8169 (9)	0.1783 (5)	0.2990 (5)	0.0493 (13)
C9	0.9999 (10)	0.1469 (6)	0.3534 (5)	0.0652 (17)
H9A	1.1007	0.2046	0.4025	0.078*
C10	1.0281 (12)	0.0335 (6)	0.3342 (6)	0.0709 (18)
H10A	1.1480	0.0130	0.3695	0.085*
C11	0.8729 (12)	−0.0534 (6)	0.2597 (6)	0.0735 (19)
H11A	0.8904	−0.1314	0.2479	0.088*
C12	0.7000 (11)	−0.0263 (5)	0.2052 (6)	0.0694 (18)
H12A	0.6031	−0.0852	0.1551	0.083*
C13	0.6657 (9)	0.0901 (5)	0.2238 (5)	0.0505 (13)
C14	0.4677 (8)	0.2285 (4)	0.1856 (5)	0.0472 (13)
C15	0.2918 (9)	0.2540 (5)	0.1121 (4)	0.0477 (13)
C16	0.3189 (10)	0.3520 (5)	0.0707 (5)	0.0584 (15)
H16A	0.4455	0.4071	0.0940	0.070*
C17	0.1619 (10)	0.3685 (5)	−0.0041 (5)	0.0611 (16)
H17A	0.1836	0.4330	−0.0326	0.073*
C18	−0.0301 (9)	0.2875 (5)	−0.0366 (5)	0.0545 (14)
C19	−0.0638 (10)	0.1897 (5)	0.0024 (5)	0.0576 (15)
H19A	−0.1927	0.1362	−0.0200	0.069*
C20	0.0981 (9)	0.1728 (5)	0.0755 (5)	0.0516 (14)
H20A	0.0783	0.1062	0.1010	0.062*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0889 (5)	0.0564 (4)	0.0746 (5)	0.0182 (3)	0.0012 (4)	0.0107 (3)
Br2	0.0645 (4)	0.0854 (5)	0.0725 (5)	0.0068 (3)	−0.0241 (3)	0.0212 (4)
N1	0.044 (3)	0.053 (3)	0.049 (3)	0.009 (2)	−0.002 (2)	0.009 (2)
N2	0.048 (3)	0.056 (3)	0.057 (3)	−0.001 (2)	0.002 (2)	0.016 (2)
C1	0.040 (3)	0.056 (3)	0.057 (4)	0.001 (3)	−0.004 (3)	0.011 (3)
C2	0.039 (3)	0.065 (4)	0.052 (3)	0.011 (3)	−0.002 (3)	0.010 (3)
C3	0.059 (4)	0.051 (3)	0.045 (3)	0.010 (3)	−0.006 (3)	0.012 (3)
C4	0.050 (4)	0.056 (3)	0.066 (4)	−0.004 (3)	−0.001 (3)	0.014 (3)
C5	0.039 (3)	0.061 (3)	0.061 (4)	0.007 (3)	0.002 (3)	0.013 (3)
C6	0.041 (3)	0.053 (3)	0.041 (3)	0.004 (2)	−0.008 (2)	0.010 (2)
C7	0.041 (3)	0.053 (3)	0.044 (3)	0.004 (2)	0.001 (2)	0.013 (2)
C8	0.044 (3)	0.058 (3)	0.047 (3)	0.009 (3)	0.007 (3)	0.014 (3)
C9	0.059 (4)	0.073 (4)	0.064 (4)	0.022 (3)	−0.010 (3)	0.016 (3)
C10	0.076 (5)	0.075 (4)	0.072 (4)	0.033 (4)	0.001 (4)	0.027 (4)
C11	0.084 (5)	0.059 (4)	0.087 (5)	0.027 (4)	0.018 (4)	0.027 (4)
C12	0.065 (4)	0.054 (3)	0.087 (5)	0.003 (3)	0.000 (4)	0.019 (3)
C13	0.047 (3)	0.052 (3)	0.054 (3)	0.007 (3)	0.010 (3)	0.017 (3)
C14	0.037 (3)	0.051 (3)	0.050 (3)	0.000 (2)	0.004 (2)	0.011 (3)
C15	0.042 (3)	0.058 (3)	0.041 (3)	0.005 (2)	0.001 (2)	0.011 (3)
C16	0.051 (4)	0.061 (4)	0.057 (4)	−0.008 (3)	−0.010 (3)	0.015 (3)
C17	0.063 (4)	0.059 (3)	0.061 (4)	−0.002 (3)	−0.009 (3)	0.021 (3)
C18	0.043 (3)	0.071 (4)	0.045 (3)	0.008 (3)	−0.011 (3)	0.011 (3)
C19	0.049 (3)	0.070 (4)	0.048 (3)	−0.002 (3)	−0.004 (3)	0.013 (3)
C20	0.047 (3)	0.057 (3)	0.049 (3)	0.002 (3)	−0.002 (3)	0.014 (3)

Geometric parameters (Å, °)

Br1—C3	1.913 (5)	C9—C10	1.355 (8)
Br2—C18	1.913 (5)	C9—H9A	0.9300
N1—C7	1.339 (6)	C10—C11	1.414 (9)
N1—C8	1.360 (7)	C10—H10A	0.9300
N2—C14	1.322 (7)	C11—C12	1.350 (9)
N2—C13	1.367 (7)	C11—H11A	0.9300
C1—C2	1.380 (8)	C12—C13	1.400 (8)
C1—C6	1.404 (8)	C12—H12A	0.9300
C1—H1B	0.9300	C14—C15	1.493 (7)
C2—C3	1.383 (8)	C15—C16	1.397 (8)
C2—H2B	0.9300	C15—C20	1.405 (7)
C3—C4	1.383 (8)	C16—C17	1.374 (8)
C4—C5	1.388 (8)	C16—H16A	0.9300
C4—H4A	0.9300	C17—C18	1.392 (8)
C5—C6	1.395 (7)	C17—H17A	0.9300
C5—H5A	0.9300	C18—C19	1.378 (8)
C6—C7	1.484 (7)	C19—C20	1.384 (7)
C7—C14	1.443 (7)	C19—H19A	0.9300
C8—C13	1.412 (7)	C20—H20A	0.9300
C8—C9	1.424 (7)
C7—N1—C8	117.5 (4)	C11—C10—H10A	120.4
C14—N2—C13	118.5 (4)	C12—C11—C10	121.8 (6)
C2—C1—C6	121.4 (5)	C12—C11—H11A	119.1
C2—C1—H1B	119.3	C10—C11—H11A	119.1
C6—C1—H1B	119.3	C11—C12—C13	120.4 (6)
C1—C2—C3	118.5 (5)	C11—C12—H12A	119.8
C1—C2—H2B	120.8	C13—C12—H12A	119.8
C3—C2—H2B	120.8	N2—C13—C12	120.2 (5)
C2—C3—C4	122.1 (5)	N2—C13—C8	120.9 (5)
C2—C3—Br1	118.5 (4)	C12—C13—C8	118.8 (5)
C4—C3—Br1	119.3 (4)	N2—C14—C7	120.4 (5)
C3—C4—C5	118.6 (5)	N2—C14—C15	115.8 (4)
C3—C4—H4A	120.7	C7—C14—C15	123.7 (5)
C5—C4—H4A	120.7	C16—C15—C20	118.0 (5)
C4—C5—C6	121.2 (5)	C16—C15—C14	122.4 (5)
C4—C5—H5A	119.4	C20—C15—C14	119.4 (5)
C6—C5—H5A	119.4	C17—C16—C15	121.2 (5)
C5—C6—C1	118.1 (5)	C17—C16—H16A	119.4
C5—C6—C7	120.4 (5)	C15—C16—H16A	119.4
C1—C6—C7	121.3 (5)	C16—C17—C18	119.2 (5)
N1—C7—C14	121.5 (5)	C16—C17—H17A	120.4
N1—C7—C6	114.9 (4)	C18—C17—H17A	120.4
C14—C7—C6	123.5 (5)	C19—C18—C17	121.5 (5)
N1—C8—C13	120.9 (5)	C19—C18—Br2	119.8 (4)
N1—C8—C9	119.7 (5)	C17—C18—Br2	118.6 (5)
C13—C8—C9	119.4 (5)	C18—C19—C20	118.6 (5)
C10—C9—C8	120.4 (6)	C18—C19—H19A	120.7
C10—C9—H9A	119.8	C20—C19—H19A	120.7
C8—C9—H9A	119.8	C19—C20—C15	121.5 (5)
C9—C10—C11	119.1 (6)	C19—C20—H20A	119.3
C9—C10—H10A	120.4	C15—C20—H20A	119.3
C6—C1—C2—C3	2.2 (8)	C11—C12—C13—C8	1.0 (9)
C1—C2—C3—C4	−1.9 (8)	N1—C8—C13—N2	5.8 (8)
C1—C2—C3—Br1	178.8 (4)	C9—C8—C13—N2	−176.5 (5)
C2—C3—C4—C5	0.4 (9)	N1—C8—C13—C12	−177.5 (5)
Br1—C3—C4—C5	179.7 (4)	C9—C8—C13—C12	0.2 (8)
C3—C4—C5—C6	0.9 (9)	C13—N2—C14—C7	−2.2 (8)
C4—C5—C6—C1	−0.6 (8)	C13—N2—C14—C15	174.7 (5)
C4—C5—C6—C7	−176.0 (5)	N1—C7—C14—N2	6.1 (8)
C2—C1—C6—C5	−1.0 (8)	C6—C7—C14—N2	−171.5 (5)
C2—C1—C6—C7	174.4 (5)	N1—C7—C14—C15	−170.5 (5)
C8—N1—C7—C14	−3.8 (8)	C6—C7—C14—C15	11.9 (8)
C8—N1—C7—C6	174.0 (5)	N2—C14—C15—C16	−140.4 (6)
C5—C6—C7—N1	54.7 (7)	C7—C14—C15—C16	36.3 (8)
C1—C6—C7—N1	−120.5 (6)	N2—C14—C15—C20	34.6 (7)
C5—C6—C7—C14	−127.6 (6)	C7—C14—C15—C20	−148.6 (6)
C1—C6—C7—C14	57.2 (7)	C20—C15—C16—C17	−0.3 (9)
C7—N1—C8—C13	−1.9 (8)	C14—C15—C16—C17	174.8 (5)
C7—N1—C8—C9	−179.6 (5)	C15—C16—C17—C18	1.7 (9)
N1—C8—C9—C10	177.2 (6)	C16—C17—C18—C19	−1.6 (9)
C13—C8—C9—C10	−0.5 (9)	C16—C17—C18—Br2	−178.0 (5)
C8—C9—C10—C11	−0.3 (10)	C17—C18—C19—C20	0.1 (9)
C9—C10—C11—C12	1.5 (11)	Br2—C18—C19—C20	176.5 (4)
C10—C11—C12—C13	−1.9 (11)	C18—C19—C20—C15	1.3 (9)
C14—N2—C13—C12	179.9 (6)	C16—C15—C20—C19	−1.2 (8)
C14—N2—C13—C8	−3.5 (8)	C14—C15—C20—C19	−176.5 (5)
C11—C12—C13—N2	177.7 (6)