3,6,8-Tribromo­quinoline

Abstract

The title mol­ecule, C₉H₄Br₃N, is almost planar, the maximum deviation being 0.110 (1) Å. The crystal structure is stabilized by weak aromatic π–π inter­actions [centroid–centroid distance = 3.802 (4) Å] between the pyridine and benzene rings of the quinoline ring systems of adjacent mol­ecules.

Related literature

For background to the synthesis of natural biologically active quinoline derivatives and for the synthesis of the title compound, see: Şahin et al. (2008 ▶). For the structure of 6,8-dibromo­quinoline, see: Çelik et al. (2010 ▶).

Experimental

Crystal data

• C₉H₄Br₃N

• M _r = 365.83

• Monoclinic,

• a = 3.9810 (2) Å

• b = 12.4176 (4) Å

• c = 19.7419 (6) Å

• β = 92.827 (3)°

• V = 974.74 (7) ų

• Z = 4

• Cu Kα radiation

• μ = 14.93 mm⁻¹

• T = 296 K

• 0.51 × 0.06 × 0.03 mm

Data collection

• Oxford Diffraction Xcalibur diffractometer with a Ruby Gemini CCD detector

• Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010 ▶) T _min = 0.049, T _max = 0.663

• 3688 measured reflections

• 1816 independent reflections

• 1484 reflections with I > 2σ(I)

• R _int = 0.060

Refinement

• R[F ² > 2σ(F ²)] = 0.054

• wR(F ²) = 0.150

• S = 1.05

• 1816 reflections

• 118 parameters

• H-atom parameters constrained

• Δρ_max = 1.45 e Å⁻³

• Δρ_min = −0.80 e Å⁻³

Data collection: CrysAlis PRO (Oxford Diffraction, 2010 ▶); cell refinement: CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SIR97 (Altomare et al., 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: ORTEP-3 for Windows (Farrugia, 1999 ▶); software used to prepare material for publication: WinGX (Farrugia, 1997 ▶) and PLATON (Spek, 2009 ▶).

Supplementary Material

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

supplementary crystallographic information

Comment

The presence of quinoline skeleton in the framework of pharmacologically active compounds and natural products has spurred on the development of different strategies for their synthesis. The lithium–halogen exchange reaction of the title compound (I) may serve for the synthesis of natural biologically active quinoline derivatives, such as quinine, pentaquine, and plasmoquine (Şahin et al., 2008). In this paper we report a one pot synthesis of (I) with high yield (90%) and its crystal structure.

The title molecule is almost planar, with the maximum and minimum deviations from the mean plane being 0.110 (1) and -0.001 (6) Å for Br2 and C4, respectively. Its crystal structure is stabilized by weak π–π stacking interactions between the pyridine and benzene rings of the quinoline ring systems of the adjacent molecules [Cg1···Cg2ⁱ = 3.802 (4) Å; symmetry code: (i) 1 + x, y, z; Cg1 and Cg2 are centroids of the N1/C1/C6–C9 pyridine and C1–C6 benzene rings of the quinoline ring system, respectively].

The crystal structure of 6,8-dibromoquinoline has been reported recently Çelik et al. (2010).

Experimental

6,8-Dibromo-1,2,3,4-tetrahydroquinoline was synthesized according to the literature method (Şahin et al., 2008). To a solution of 6,8-dibromo-1,2,3,4-tetrahydroquinoline (0.5 g, 3.75 mmol, 1 eq) in CHCl₃ (20 ml) was dropped bromine (1.8 g, 11.25 mmol, 3 eq) in CHCl₃ (10 ml) over 5 min in the dark and at room temperature. After completion of the reaction (bromine consumed completely, 3 days), the solid was dissolved in CHCl₃ (35 ml) and the organic layer was washed with 5% NaHCO₃ solution (3x20 ml) and dried over Na₂SO₄. After evaporation of the solvent, the crude material (1.32 g) was passed through a short alumina column eluting with EtOAc–hexane (1:12, 75 ml) (hexane/ethyl acetate, 9:1, R_f= 0.65). Colourless solid residue was obtained. The mixture was recrystallized from the solvent (benzene) in a freezer (263 K) to give pure 3,6,8-tribromoquinoline in 90% yield (1.24 g) if the form of colourless neddle shaped crystals; m.p. 441–443 K.

Refinement

H atoms were included in geometric positions with C—H = 0.93 Å and refined by using a riding model [U_iso(H) = 1.2U_eq(C)]. The highest peak in the final difference map was located 0.92Å from Br2, while the deepest hole was located 1.05Å from Br3.

Figures

Fig. 1.

The title molecule with the atom numbering scheme. Displacement ellipsoids for have been drawn at the 50% probability level.

Crystal data

C9H4Br3N	F(000) = 680
Mr = 365.83	Dx = 2.493 Mg m−3
Monoclinic, P21/n	Cu Kα radiation, λ = 1.5418 Å
Hall symbol: -P 2yn	Cell parameters from 2025 reflections
a = 3.9810 (2) Å	θ = 3.6–70.4°
b = 12.4176 (4) Å	µ = 14.93 mm−1
c = 19.7419 (6) Å	T = 296 K
β = 92.827 (3)°	Needle, colourless
V = 974.74 (7) Å3	0.51 × 0.06 × 0.03 mm
Z = 4

Data collection

Oxford Diffraction Xcalibur diffractometer with a Ruby Gemini CCD detector	1816 independent reflections
Radiation source: Enhance (Cu) X-ray Source	1484 reflections with I > 2σ(I)
graphite	Rint = 0.060
Detector resolution: 10.2673 pixels mm-1	θmax = 70.6°, θmin = 5.7°
ω scans	h = −4→4
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2010)	k = −9→15
Tmin = 0.049, Tmax = 0.663	l = −22→24
3688 measured reflections

Refinement

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)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.150	H-atom parameters constrained
S = 1.05	w = 1/[σ2(Fo2) + (0.1066P)2] where P = (Fo2 + 2Fc2)/3
1816 reflections	(Δ/σ)max = 0.001
118 parameters	Δρmax = 1.45 e Å−3
0 restraints	Δρmin = −0.79 e Å−3

Special details

Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles

Refinement. Refinement on F2 for ALL reflections except those flagged by the user for potential systematic errors. Weighted R-factors wR and all goodnesses of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The observed criterion of F2 > σ(F2) is used only for calculating -R-factor-obs 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	0.6380 (2)	0.29099 (6)	0.90189 (4)	0.0568 (3)
Br2	0.11453 (19)	−0.12590 (6)	0.92944 (4)	0.0525 (3)
Br3	0.7497 (2)	0.08258 (7)	0.56672 (4)	0.0608 (3)
N1	0.7203 (14)	0.2168 (5)	0.7553 (3)	0.0440 (17)
C1	0.5666 (16)	0.1396 (5)	0.7921 (3)	0.0396 (17)
C2	0.5134 (15)	0.1576 (5)	0.8619 (3)	0.0404 (17)
C3	0.3758 (16)	0.0808 (5)	0.9010 (3)	0.0428 (17)
C4	0.2822 (16)	−0.0184 (5)	0.8725 (3)	0.0425 (17)
C5	0.3078 (15)	−0.0384 (5)	0.8042 (3)	0.0405 (17)
C6	0.4583 (15)	0.0399 (5)	0.7636 (3)	0.0387 (17)
C7	0.5126 (16)	0.0209 (5)	0.6946 (3)	0.0426 (17)
C8	0.6665 (16)	0.0996 (5)	0.6597 (3)	0.0429 (17)
C9	0.7713 (17)	0.1961 (6)	0.6919 (3)	0.0462 (17)
H3	0.34400	0.09420	0.94660	0.0520*
H5	0.22720	−0.10250	0.78520	0.0480*
H7	0.44560	−0.04330	0.67380	0.0510*
H9	0.88170	0.24730	0.66670	0.0550*

Atomic displacement parameters (Ų)

	U11	U22	U33	U12	U13	U23
Br1	0.0752 (6)	0.0456 (4)	0.0506 (5)	−0.0125 (3)	0.0119 (4)	−0.0120 (3)
Br2	0.0622 (5)	0.0498 (5)	0.0464 (4)	−0.0097 (3)	0.0107 (3)	0.0057 (3)
Br3	0.0798 (6)	0.0652 (5)	0.0385 (4)	0.0047 (4)	0.0132 (3)	−0.0003 (3)
N1	0.053 (3)	0.040 (3)	0.039 (3)	−0.003 (2)	0.003 (2)	0.002 (2)
C1	0.043 (3)	0.032 (3)	0.044 (3)	0.002 (2)	0.003 (2)	0.002 (2)
C2	0.044 (3)	0.037 (3)	0.040 (3)	0.002 (2)	0.000 (2)	−0.004 (2)
C3	0.042 (3)	0.050 (3)	0.037 (3)	−0.003 (3)	0.007 (2)	−0.006 (3)
C4	0.046 (3)	0.039 (3)	0.043 (3)	0.000 (3)	0.006 (2)	0.003 (2)
C5	0.045 (3)	0.038 (3)	0.038 (3)	0.000 (2)	−0.004 (2)	0.000 (2)
C6	0.039 (3)	0.038 (3)	0.039 (3)	0.006 (2)	0.000 (2)	0.003 (2)
C7	0.048 (3)	0.041 (3)	0.039 (3)	0.007 (3)	0.005 (2)	−0.003 (2)
C8	0.045 (3)	0.047 (3)	0.037 (3)	0.010 (3)	0.004 (2)	0.003 (2)
C9	0.053 (3)	0.047 (3)	0.039 (3)	−0.002 (3)	0.006 (3)	0.004 (2)

Geometric parameters (Å, °)

Br1—C2	1.891 (6)	C4—C5	1.380 (8)
Br2—C4	1.888 (6)	C5—C6	1.412 (9)
Br3—C8	1.893 (6)	C6—C7	1.410 (8)
N1—C1	1.366 (9)	C7—C8	1.359 (9)
N1—C9	1.303 (8)	C8—C9	1.410 (9)
C1—C2	1.422 (8)	C3—H3	0.9300
C1—C6	1.418 (9)	C5—H5	0.9300
C2—C3	1.359 (9)	C7—H7	0.9300
C3—C4	1.397 (9)	C9—H9	0.9300
Br1···N1	3.070 (6)	C7···C8ii	3.542 (9)
Br1···Br3i	3.6969 (12)	C7···Br1iv	3.738 (6)
Br1···C7i	3.738 (6)	C8···C7viii	3.542 (9)
Br2···C4ii	3.696 (6)	C9···Br2ix	3.553 (7)
Br2···C9iii	3.553 (7)	C9···C6viii	3.587 (9)
Br3···Br1iv	3.6969 (12)	C5···H9iv	2.9800
Br3···Br3v	3.8186 (12)	H3···Br2vii	3.1500
Br1···H7i	3.0800	H3···Br2vi	3.2000
Br2···H9iii	3.1000	H5···H7	2.5100
Br2···H3vi	3.2000	H5···H9iv	2.5800
Br2···H9iv	3.2400	H7···H5	2.5100
Br2···H3vii	3.1500	H7···Br1iv	3.0800
N1···Br1	3.070 (6)	H9···Br2ix	3.1000
C4···Br2viii	3.696 (6)	H9···Br2i	3.2400
C5···C6ii	3.572 (8)	H9···C5i	2.9800
C6···C5viii	3.572 (8)	H9···H5i	2.5800
C6···C9ii	3.587 (9)
C1—N1—C9	117.9 (6)	C5—C6—C7	121.5 (6)
N1—C1—C2	119.8 (6)	C6—C7—C8	117.7 (6)
N1—C1—C6	122.5 (6)	Br3—C8—C7	121.1 (5)
C2—C1—C6	117.7 (5)	Br3—C8—C9	118.0 (5)
Br1—C2—C1	119.6 (5)	C7—C8—C9	120.9 (6)
Br1—C2—C3	118.8 (5)	N1—C9—C8	123.0 (6)
C1—C2—C3	121.6 (6)	C2—C3—H3	120.00
C2—C3—C4	119.8 (6)	C4—C3—H3	120.00
Br2—C4—C3	118.6 (4)	C4—C5—H5	120.00
Br2—C4—C5	120.0 (5)	C6—C5—H5	121.00
C3—C4—C5	121.4 (6)	C6—C7—H7	121.00
C4—C5—C6	119.0 (6)	C8—C7—H7	121.00
C1—C6—C5	120.3 (5)	N1—C9—H9	119.00
C1—C6—C7	118.1 (5)	C8—C9—H9	118.00
C9—N1—C1—C2	178.4 (6)	C2—C3—C4—Br2	176.6 (5)
C9—N1—C1—C6	−0.9 (9)	C2—C3—C4—C5	−3.9 (10)
C1—N1—C9—C8	1.9 (10)	Br2—C4—C5—C6	−175.1 (5)
N1—C1—C2—Br1	2.9 (8)	C3—C4—C5—C6	5.4 (9)
N1—C1—C2—C3	−176.9 (6)	C4—C5—C6—C1	−3.0 (9)
C6—C1—C2—Br1	−177.8 (4)	C4—C5—C6—C7	175.5 (6)
C6—C1—C2—C3	2.5 (9)	C1—C6—C7—C8	0.1 (9)
N1—C1—C6—C5	178.5 (6)	C5—C6—C7—C8	−178.4 (6)
N1—C1—C6—C7	−0.1 (9)	C6—C7—C8—Br3	−179.7 (5)
C2—C1—C6—C5	−0.9 (9)	C6—C7—C8—C9	0.8 (9)
C2—C1—C6—C7	−179.5 (6)	Br3—C8—C9—N1	178.6 (5)
Br1—C2—C3—C4	−179.9 (5)	C7—C8—C9—N1	−1.9 (10)
C1—C2—C3—C4	−0.2 (9)

Symmetry codes: (i) −x+3/2, y+1/2, −z+3/2; (ii) x−1, y, z; (iii) −x+1/2, y−1/2, −z+3/2; (iv) −x+3/2, y−1/2, −z+3/2; (v) −x+1, −y, −z+1; (vi) −x+1, −y, −z+2; (vii) −x, −y, −z+2; (viii) x+1, y, z; (ix) −x+1/2, y+1/2, −z+3/2.

Table 1 π–π Stacking interactions in the title structure

Cg1 and Cg2 are centroids of the N1/C1/C6–C9 pyridine and C1–C6 benzene rings of the quinoline ring system, respectively.

Ring 1	Ring 2(sym)	(Ring 1)···(Ring 2) (Å)
Cg1	Cg2i	3.802 (4)

ⁱ: 1+x, y, z.