3,3′,5,5′-Tetra­bromo-2,2′-bi­thio­phene

The title compound, C₈H₂Br₄S₂, was prepared by bromination of 2,2′-bithio­phene with bromine. The mol­ecule is located on a crystallographic twofold rotation axis, thereby imposing equal geometry of the two thio­phene rings. Each five-membered ring is planar [maximum deviation 0.011 (9) Å] and the dihedral angle between the planes through the rings is 47.2 (4)°. The mol­ecules are arranged to minimize intramolecular contacts between the 3-3′ and 5-5′-bromine atoms.

Related literature

For use of the title compound as an intermediate in the synthesis of oligothiophenes and polythiophenes, see: Roncali (1997); Funahashi et al. (2005). For synthetic methods, see: Takahashi et al. (2006); Lin et al. (2005).

Experimental

Crystal data

• C₈H₂Br₄S₂

• M_r = 481.86

• Monoclinic, C 2/c

• a = 17.164 (3) Å

• b = 4.0153 (7) Å

• c = 18.655 (3) Å

• β = 115.395 (3)°

• V = 1161.4 (4) ų

• Z = 4

• Mo Kα radiation

• μ = 14.18 mm⁻¹

• T = 293 K

• 0.40 × 0.17 × 0.05 mm

Data collection

• Bruker SMART CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 2004) T_min = 0.258, T_max = 1.000 (expected range = 0.122–0.472)

• 2792 measured reflections

• 1077 independent reflections

• 886 reflections with I > 2σ(I)

• R_int = 0.146

Refinement

• R[F² > 2σ(F²)] = 0.078

• wR(F²) = 0.208

• S = 1.00

• 1077 reflections

• 64 parameters

• H-atom parameters constrained

• Δρ_max = 1.15 e Å⁻³

• Δρ_min = −1.06 e Å⁻³

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL.

Supporting information

S1. Comment

3,3',5,5'-Tetrabromo-2,2'-bithiophene is an important intermediate compound in the synthesis of oligothiophenes and polythiophenes which have recently attracted attention as materials showing conductive, semiconductive, nonlinear optical (NLO), and liquid crystalline characteristics (Roncali, 1997; Funahashi et al., 2005). While synthesis of 3,3',5,5'-tetrabromo-2,2'-bithiophene could be achieved by coupling of 2,3-dibromothiophene (Takahashi et al., 2006) or bromination of 2,2'-bithiophene (Lin et al., 2005), its single crystal structure has not been reported. Herein we present the single crystal structure of the title compound. A molecule of the title compound is located on a crystallographic two-fold rotation axis, thereby imposing equal geometry of the two rings. Each 5-membered ring is planar and the dihedral angle between the planes thorugh the rings is 47.2 (4)°. The molecules arrange in such a fashion that both pairs of bromine atoms (3- and 3'-bromine and 5- and 5'-bromine) lie far away to each other.

Related literature

For general background, see: Roncali (1997); Funahashi et al. (2005). For synthetic methods, see: Takahashi et al. (2006); Lin et al. (2005).

S2. Experimental

The title compound was prepared as reported in the literature (Lin et al., 2005). Single crystals suitable for X-ray diffraction measurement were obtained by slow evaporation of a solution in ethanol (m.p. 413 K; literature value: 413–414 K (Takahashi et al., 2006)).

S3. Refinement

All H atoms were placed at calculated positions and refined using a riding model approximation, with C—H = 0.93 Å and with U_iso(H) = 1.2U_eq(C).

Computing details

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

Fig. 1. A view of the molecule of the title compound. Displacement ellipsoids are drawn at the 30% probability level.

3,3',5,5'-Tetrabromo-2,2'-bithiophene

Crystal data

C8H2Br4S2	Dx = 2.756 Mg m^−3
Mr = 481.86	Melting point = 413–414 K
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
a = 17.164 (3) Å	Cell parameters from 1249 reflections
b = 4.0153 (7) Å	θ = 4.8–55.3°
c = 18.655 (3) Å	µ = 14.18 mm^−1
β = 115.395 (3)°	T = 293 K
V = 1161.4 (4) Å^3	Prismatic, yellow
Z = 4	0.40 × 0.17 × 0.05 mm
F(000) = 888

Data collection

Bruker SMART CCD area-detector diffractometer	1077 independent reflections
Radiation source: fine-focus sealed tube	886 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.146
ϕ and ω scans	θmax = 25.5°, θmin = 2.4°
Absorption correction: multi-scan (SADABS; Sheldrick, 2004)	h = −20→18
Tmin = 0.258, Tmax = 1.000	k = −4→4
2792 measured reflections	l = −22→21

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)] = 0.078	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.208	H-atom parameters constrained
S = 1.00	w = 1/[σ^2(Fo^2) + (0.1428P)^2] where P = (Fo^2 + 2Fc^2)/3
1077 reflections	(Δ/σ)max < 0.001
64 parameters	Δρmax = 1.15 e Å^−3
0 restraints	Δρmin = −1.06 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
Br1	0.17755 (6)	0.2991 (3)	0.27753 (6)	0.0443 (5)
Br2	0.11718 (8)	0.7463 (3)	0.54198 (6)	0.0562 (5)
S1	−0.00225 (17)	0.7354 (6)	0.36201 (13)	0.0393 (7)
C1	0.0301 (5)	0.581 (2)	0.2918 (4)	0.0331 (17)
C2	0.1140 (5)	0.480 (2)	0.3291 (4)	0.0354 (17)
C4	0.0973 (6)	0.650 (2)	0.4373 (5)	0.041 (2)
C3	0.1540 (5)	0.521 (2)	0.4129 (4)	0.0411 (19)
H3	0.2109	0.4669	0.4459	0.049*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0524 (7)	0.0457 (7)	0.0483 (7)	0.0023 (4)	0.0344 (6)	−0.0050 (4)
Br2	0.0735 (9)	0.0718 (9)	0.0312 (7)	−0.0072 (5)	0.0298 (6)	−0.0063 (4)
S1	0.0508 (15)	0.0482 (13)	0.0306 (12)	0.0043 (9)	0.0286 (11)	−0.0007 (8)
C1	0.050 (5)	0.030 (4)	0.034 (4)	0.000 (4)	0.032 (4)	0.000 (3)
C2	0.052 (5)	0.030 (4)	0.034 (4)	−0.006 (3)	0.028 (4)	0.001 (3)
C4	0.059 (6)	0.042 (5)	0.028 (4)	0.003 (4)	0.025 (4)	0.006 (3)
C3	0.050 (5)	0.046 (5)	0.035 (4)	−0.003 (4)	0.025 (4)	0.005 (4)

Geometric parameters (Å, º)

Br1—C2	1.882 (8)	C1—C1^i	1.455 (15)
Br2—C4	1.873 (8)	C2—C3	1.422 (11)
S1—C4	1.719 (9)	C4—C3	1.342 (11)
S1—C1	1.741 (7)	C3—H3	0.9300
C1—C2	1.365 (11)
C4—S1—C1	91.0 (4)	C3—C4—S1	114.3 (6)
C2—C1—C1^i	131.0 (8)	C3—C4—Br2	126.8 (7)
C2—C1—S1	109.2 (6)	S1—C4—Br2	118.9 (5)
C1^i—C1—S1	119.8 (7)	C4—C3—C2	109.8 (8)
C1—C2—C3	115.6 (7)	C4—C3—H3	125.1
C1—C2—Br1	124.7 (6)	C2—C3—H3	125.1
C3—C2—Br1	119.6 (6)
C4—S1—C1—C2	−0.9 (6)	C1—S1—C4—C3	1.7 (7)
C4—S1—C1—C1^i	179.8 (5)	C1—S1—C4—Br2	−179.2 (5)
C1^i—C1—C2—C3	179.2 (5)	S1—C4—C3—C2	−1.9 (10)
S1—C1—C2—C3	0.1 (9)	Br2—C4—C3—C2	179.1 (6)
C1^i—C1—C2—Br1	−0.2 (11)	C1—C2—C3—C4	1.2 (11)
S1—C1—C2—Br1	−179.4 (4)	Br1—C2—C3—C4	−179.4 (6)

Symmetry code: (i) −x, y, −z+1/2.