3,6,8-Tribromo­quinoline

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.

Key indicators

• Single-crystal X-ray study
• T = 296 K
• Mean [sigma](C-C) = 0.009 Å
• R factor = 0.054
• wR factor = 0.150
• Data-to-parameter ratio = 15.4

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT029_ALERT_3_C _diffrn_measured_fraction_theta_full Low .......       0.98
PLAT341_ALERT_3_C Low Bond Precision on  C-C Bonds (x 1000) Ang ..          9
PLAT910_ALERT_3_C Missing # of FCF Reflections Below Th(Min) .....          2
PLAT911_ALERT_3_C Missing # FCF Refl Between THmin & STh/L=  0.600         20
PLAT912_ALERT_4_C Missing # of FCF Reflections Above STh/L=  0.600         20

Alert level G
PLAT072_ALERT_2_G SHELXL First  Parameter in WGHT Unusually Large.       0.11
PLAT128_ALERT_4_G Alternate Setting of Space-group P21/c   .......      P21/n

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   5 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   0 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   4 ALERT type 3 Indicator that the structure quality may be low
   2 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. 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).

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).

S2. 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.

S3. 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.

Computing details

Data collection: CrysAlis PRO (Oxford Diffraction, 2010); cell refinement: CrysAlis PRO (Oxford Diffraction, 2010); data reduction: CrysAlis PRO (Oxford Diffraction, 2010); 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).

Figures

Fig. 1. The title molecule with the atom numbering scheme. Displacement ellipsoids for have been drawn at the 50% probability level.

3,6,8-Tribromoquinoline

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) Å^3	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 monochromator	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 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)] = 0.054	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.150	H-atom parameters constrained
S = 1.05	w = 1/[σ^2(Fo^2) + (0.1066P)^2] where P = (Fo^2 + 2Fc^2)/3
1816 reflections	(Δ/σ)max = 0.001
118 parameters	Δρmax = 1.45 e Å^−3
0 restraints	Δρmin = −0.80 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)

	U^11	U^22	U^33	U^12	U^13	U^23
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, º)

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···C8^ii	3.542 (9)
Br1···Br3^i	3.6969 (12)	C7···Br1^iv	3.738 (6)
Br1···C7^i	3.738 (6)	C8···C7^viii	3.542 (9)
Br2···C4^ii	3.696 (6)	C9···Br2^ix	3.553 (7)
Br2···C9^iii	3.553 (7)	C9···C6^viii	3.587 (9)
Br3···Br1^iv	3.6969 (12)	C5···H9^iv	2.9800
Br3···Br3^v	3.8186 (12)	H3···Br2^vii	3.1500
Br1···H7^i	3.0800	H3···Br2^vi	3.2000
Br2···H9^iii	3.1000	H5···H7	2.5100
Br2···H3^vi	3.2000	H5···H9^iv	2.5800
Br2···H9^iv	3.2400	H7···H5	2.5100
Br2···H3^vii	3.1500	H7···Br1^iv	3.0800
N1···Br1	3.070 (6)	H9···Br2^ix	3.1000
C4···Br2^viii	3.696 (6)	H9···Br2^i	3.2400
C5···C6^ii	3.572 (8)	H9···C5^i	2.9800
C6···C5^viii	3.572 (8)	H9···H5^i	2.5800
C6···C9^ii	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.