7,8-Dichloro-2,3-diphenyl­quinoxaline

The title compound, C₂₀H₁₂Cl₂N₂, was synthesized from the reaction of equimolar amounts of 4,5-dichloro­benzene-1,2-diamine and benzil in acetonitrile, utilizing mol­ecular iodine as the catalyst. The crystal structure was determined at 110 K. The dihedral angle between the two phenyl rings is 57.0 (1)°.

Key indicators

• Single-crystal X-ray study
• T = 110 K
• Mean [sigma](C-C)= 0.002 Å
• R factor = 0.045
• wR factor = 0.108
• Data-to-parameter ratio = 33.6

checkCIF/PLATON results

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Computing details

Data collection: COLLECT (Nonius, 2000); cell refinement: DENZO and SCALEPACK (Otwinowski & Minor, 1997); data reduction: DENZO and SCALEPACK; program(s) used to solve structure: SIR97 (Altomare et al., 1999); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 (Farrugia, 1997); software used to prepare material for publication: SHELXL97.

7,8-dichloro-2,3-diphenylquinoxaline

Crystal data

C20H12Cl2N2	F(000) = 1440
Mr = 351.22	Dx = 1.465 Mg m^−3
Monoclinic, C2/c	Melting point: 157 K
Hall symbol: -C 2yc	Mo Kα radiation, λ = 0.71073 Å
a = 25.158 (3) Å	Cell parameters from 7159 reflections
b = 7.8022 (10) Å	θ = 2.5–35.6°
c = 18.678 (2) Å	µ = 0.41 mm^−1
β = 119.697 (6)°	T = 110 K
V = 3184.7 (7) Å^3	Fragment cut from a needle, light yellow
Z = 8	0.23 × 0.20 × 0.15 mm

Data collection

Nonius KappaCCD (with an Oxford Cryosystems Cryostream cooler) diffractometer	7301 independent reflections
Radiation source: fine-focus sealed tube	5571 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.034
ω scans with κ offsets	θmax = 35.6°, θmin = 2.8°
Absorption correction: multi-scan (DENZO and SCALEPACK; Otwinowski & Minor, 1997)	h = −41→41
Tmin = 0.912, Tmax = 0.941	k = −12→12
33023 measured reflections	l = −30→30

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.045	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.108	H-atom parameters constrained
S = 1.03	w = 1/[σ^2(Fo^2) + (0.0445P)^2 + 2.2948P] where P = (Fo^2 + 2Fc^2)/3
7301 reflections	(Δ/σ)max = 0.001
217 parameters	Δρmax = 0.41 e Å^−3
0 restraints	Δρmin = −0.46 e Å^−3

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
Cl1	0.429837 (15)	0.96081 (4)	0.63592 (2)	0.02640 (7)
Cl2	0.348183 (14)	0.93454 (4)	0.44249 (2)	0.02585 (7)
N1	0.60166 (4)	0.68277 (12)	0.60995 (6)	0.01694 (17)
N2	0.52864 (4)	0.65593 (12)	0.43782 (5)	0.01642 (16)
C1	0.62480 (5)	0.62797 (14)	0.56404 (6)	0.01553 (18)
C2	0.58689 (5)	0.60849 (13)	0.47537 (6)	0.01490 (17)
C3	0.50576 (5)	0.72248 (14)	0.48441 (6)	0.01569 (18)
C4	0.44483 (5)	0.78390 (15)	0.44513 (7)	0.0189 (2)
H4	0.4199	0.7760	0.3870	0.023*
C5	0.42193 (5)	0.85499 (14)	0.49149 (7)	0.0190 (2)
C6	0.45863 (5)	0.86539 (14)	0.57886 (7)	0.0189 (2)
C7	0.51715 (5)	0.80280 (15)	0.61807 (7)	0.01835 (19)
H7	0.5410	0.8066	0.6765	0.022*
C8	0.54193 (5)	0.73240 (14)	0.57108 (6)	0.01614 (18)
C9	0.69186 (5)	0.59604 (14)	0.61074 (6)	0.01624 (18)
C10	0.73134 (5)	0.68176 (15)	0.59049 (7)	0.0188 (2)
H10	0.7152	0.7564	0.5442	0.023*
C11	0.79426 (5)	0.65820 (17)	0.63782 (8)	0.0241 (2)
H11	0.8211	0.7177	0.6243	0.029*
C12	0.81791 (6)	0.54735 (18)	0.70495 (8)	0.0279 (3)
H12	0.8609	0.5308	0.7370	0.033*
C13	0.77900 (6)	0.46080 (17)	0.72540 (7)	0.0259 (2)
H13	0.7953	0.3845	0.7710	0.031*
C14	0.71607 (6)	0.48614 (16)	0.67888 (7)	0.0208 (2)
H14	0.6895	0.4287	0.6934	0.025*
C15	0.60876 (5)	0.53687 (13)	0.42053 (6)	0.01525 (18)
C16	0.65841 (5)	0.42416 (14)	0.44777 (7)	0.0183 (2)
H16	0.6803	0.3914	0.5041	0.022*
C17	0.67590 (6)	0.35980 (15)	0.39308 (7)	0.0209 (2)
H17	0.7100	0.2846	0.4125	0.025*
C18	0.64379 (6)	0.40483 (15)	0.31012 (7)	0.0211 (2)
H18	0.6560	0.3614	0.2730	0.025*
C19	0.59364 (6)	0.51383 (15)	0.28197 (7)	0.0200 (2)
H19	0.5711	0.5433	0.2252	0.024*
C20	0.57628 (5)	0.57984 (15)	0.33652 (6)	0.01752 (19)
H20	0.5421	0.6547	0.3167	0.021*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.03114 (16)	0.02596 (14)	0.03237 (15)	0.00166 (11)	0.02356 (13)	−0.00405 (11)
Cl2	0.02373 (14)	0.02590 (14)	0.03141 (15)	0.00897 (11)	0.01630 (12)	0.00952 (11)
N1	0.0183 (4)	0.0197 (4)	0.0147 (4)	−0.0017 (3)	0.0096 (3)	−0.0009 (3)
N2	0.0181 (4)	0.0181 (4)	0.0146 (4)	−0.0010 (3)	0.0093 (3)	0.0000 (3)
C1	0.0177 (4)	0.0163 (4)	0.0136 (4)	−0.0020 (4)	0.0085 (4)	−0.0003 (3)
C2	0.0179 (4)	0.0151 (4)	0.0136 (4)	−0.0010 (3)	0.0092 (4)	0.0001 (3)
C3	0.0175 (4)	0.0160 (4)	0.0156 (4)	−0.0012 (3)	0.0098 (4)	0.0013 (3)
C4	0.0194 (5)	0.0198 (5)	0.0184 (5)	0.0011 (4)	0.0101 (4)	0.0030 (4)
C5	0.0195 (5)	0.0161 (4)	0.0247 (5)	0.0022 (4)	0.0135 (4)	0.0044 (4)
C6	0.0248 (5)	0.0155 (4)	0.0239 (5)	−0.0007 (4)	0.0179 (4)	−0.0007 (4)
C7	0.0216 (5)	0.0202 (5)	0.0170 (4)	−0.0023 (4)	0.0124 (4)	−0.0015 (4)
C8	0.0181 (4)	0.0163 (4)	0.0162 (4)	−0.0019 (4)	0.0102 (4)	−0.0006 (4)
C9	0.0169 (4)	0.0182 (4)	0.0133 (4)	0.0002 (4)	0.0072 (4)	−0.0027 (3)
C10	0.0185 (5)	0.0190 (5)	0.0194 (5)	−0.0006 (4)	0.0098 (4)	−0.0026 (4)
C11	0.0183 (5)	0.0266 (6)	0.0277 (6)	−0.0020 (4)	0.0116 (5)	−0.0071 (5)
C12	0.0190 (5)	0.0343 (7)	0.0231 (5)	0.0059 (5)	0.0050 (4)	−0.0076 (5)
C13	0.0279 (6)	0.0294 (6)	0.0149 (5)	0.0106 (5)	0.0066 (4)	0.0002 (4)
C14	0.0246 (5)	0.0227 (5)	0.0155 (4)	0.0029 (4)	0.0101 (4)	0.0001 (4)
C15	0.0176 (4)	0.0164 (4)	0.0130 (4)	−0.0027 (4)	0.0086 (4)	−0.0016 (3)
C16	0.0228 (5)	0.0177 (5)	0.0156 (4)	−0.0001 (4)	0.0105 (4)	−0.0005 (4)
C17	0.0247 (5)	0.0203 (5)	0.0204 (5)	0.0014 (4)	0.0133 (4)	−0.0024 (4)
C18	0.0282 (6)	0.0218 (5)	0.0180 (5)	−0.0025 (4)	0.0150 (4)	−0.0037 (4)
C19	0.0255 (5)	0.0227 (5)	0.0135 (4)	−0.0028 (4)	0.0108 (4)	−0.0014 (4)
C20	0.0185 (5)	0.0206 (5)	0.0137 (4)	−0.0022 (4)	0.0082 (4)	−0.0011 (4)

Geometric parameters (Å, º)

Cl1—C6	1.7264 (11)	C10—H10	0.9500
Cl2—C5	1.7270 (12)	C11—C12	1.3911 (19)
N1—C1	1.3236 (13)	C11—H11	0.9500
N1—C8	1.3616 (14)	C12—C13	1.389 (2)
N2—C2	1.3259 (14)	C12—H12	0.9500
N2—C3	1.3619 (13)	C13—C14	1.3920 (18)
C1—C2	1.4527 (14)	C13—H13	0.9500
C1—C9	1.4871 (15)	C14—H14	0.9500
C2—C15	1.4908 (14)	C15—C16	1.4011 (16)
C3—C8	1.4125 (15)	C15—C20	1.4042 (15)
C3—C4	1.4153 (16)	C16—C17	1.3908 (15)
C4—C5	1.3726 (16)	C16—H16	0.9500
C4—H4	0.9500	C17—C18	1.3917 (16)
C5—C6	1.4245 (17)	C17—H17	0.9500
C6—C7	1.3688 (16)	C18—C19	1.3908 (18)
C7—C8	1.4153 (15)	C18—H18	0.9500
C7—H7	0.9500	C19—C20	1.3910 (15)
C9—C10	1.3962 (15)	C19—H19	0.9500
C9—C14	1.3993 (16)	C20—H20	0.9500
C10—C11	1.3907 (16)
C1—N1—C8	118.02 (9)	C9—C10—H10	119.9
C2—N2—C3	118.34 (9)	C10—C11—C12	119.94 (12)
N1—C1—C2	121.43 (10)	C10—C11—H11	120.0
N1—C1—C9	114.17 (9)	C12—C11—H11	120.0
C2—C1—C9	124.36 (9)	C13—C12—C11	120.32 (12)
N2—C2—C1	120.20 (9)	C13—C12—H12	119.8
N2—C2—C15	115.37 (9)	C11—C12—H12	119.8
C1—C2—C15	124.43 (9)	C12—C13—C14	119.86 (12)
N2—C3—C8	121.12 (10)	C12—C13—H13	120.1
N2—C3—C4	119.34 (10)	C14—C13—H13	120.1
C8—C3—C4	119.54 (10)	C13—C14—C9	120.18 (11)
C5—C4—C3	119.67 (10)	C13—C14—H14	119.9
C5—C4—H4	120.2	C9—C14—H14	119.9
C3—C4—H4	120.2	C16—C15—C20	118.43 (10)
C4—C5—C6	120.62 (10)	C16—C15—C2	123.49 (9)
C4—C5—Cl2	119.17 (9)	C20—C15—C2	118.03 (10)
C6—C5—Cl2	120.21 (9)	C17—C16—C15	120.63 (10)
C7—C6—C5	120.50 (10)	C17—C16—H16	119.7
C7—C6—Cl1	119.51 (9)	C15—C16—H16	119.7
C5—C6—Cl1	119.98 (9)	C16—C17—C18	120.41 (11)
C6—C7—C8	119.61 (10)	C16—C17—H17	119.8
C6—C7—H7	120.2	C18—C17—H17	119.8
C8—C7—H7	120.2	C19—C18—C17	119.52 (10)
N1—C8—C3	120.65 (9)	C19—C18—H18	120.2
N1—C8—C7	119.24 (10)	C17—C18—H18	120.2
C3—C8—C7	120.03 (10)	C18—C19—C20	120.31 (10)
C10—C9—C14	119.50 (10)	C18—C19—H19	119.8
C10—C9—C1	120.90 (10)	C20—C19—H19	119.8
C14—C9—C1	119.49 (10)	C19—C20—C15	120.67 (11)
C11—C10—C9	120.19 (11)	C19—C20—H20	119.7
C11—C10—H10	119.9	C15—C20—H20	119.7
C8—N1—C1—C2	−4.61 (16)	C6—C7—C8—N1	174.89 (10)
C8—N1—C1—C9	173.20 (9)	C6—C7—C8—C3	−1.82 (16)
C3—N2—C2—C1	−0.06 (15)	N1—C1—C9—C10	−121.65 (11)
C3—N2—C2—C15	−179.99 (9)	C2—C1—C9—C10	56.09 (15)
N1—C1—C2—N2	4.27 (16)	N1—C1—C9—C14	54.59 (14)
C9—C1—C2—N2	−173.31 (10)	C2—C1—C9—C14	−127.67 (11)
N1—C1—C2—C15	−175.81 (10)	C14—C9—C10—C11	−0.10 (16)
C9—C1—C2—C15	6.60 (17)	C1—C9—C10—C11	176.15 (10)
C2—N2—C3—C8	−3.43 (15)	C9—C10—C11—C12	0.77 (17)
C2—N2—C3—C4	176.07 (10)	C10—C11—C12—C13	−0.46 (18)
N2—C3—C4—C5	−178.41 (10)	C11—C12—C13—C14	−0.51 (19)
C8—C3—C4—C5	1.10 (16)	C12—C13—C14—C9	1.19 (18)
C3—C4—C5—C6	−0.86 (17)	C10—C9—C14—C13	−0.88 (16)
C3—C4—C5—Cl2	178.31 (8)	C1—C9—C14—C13	−177.18 (10)
C4—C5—C6—C7	−0.75 (17)	N2—C2—C15—C16	−155.16 (10)
Cl2—C5—C6—C7	−179.91 (9)	C1—C2—C15—C16	24.92 (16)
C4—C5—C6—Cl1	178.12 (9)	N2—C2—C15—C20	22.32 (14)
Cl2—C5—C6—Cl1	−1.03 (13)	C1—C2—C15—C20	−157.60 (10)
C5—C6—C7—C8	2.08 (17)	C20—C15—C16—C17	1.51 (16)
Cl1—C6—C7—C8	−176.80 (8)	C2—C15—C16—C17	178.98 (10)
C1—N1—C8—C3	1.09 (15)	C15—C16—C17—C18	−0.81 (18)
C1—N1—C8—C7	−175.60 (10)	C16—C17—C18—C19	−0.51 (18)
N2—C3—C8—N1	3.07 (16)	C17—C18—C19—C20	1.11 (18)
C4—C3—C8—N1	−176.44 (10)	C18—C19—C20—C15	−0.38 (17)
N2—C3—C8—C7	179.73 (10)	C16—C15—C20—C19	−0.92 (16)
C4—C3—C8—C7	0.23 (16)	C2—C15—C20—C19	−178.53 (10)