2,3,4-Tribromo­thio­phene

Tony M Kuriger; Stephen C Moratti; Jim Simpson

doi:10.1107/S1600536808006600

. 2008 Mar 14;64(Pt 4):o709. doi: 10.1107/S1600536808006600

2,3,4-Tribromothiophene

Tony M Kuriger ^a, Stephen C Moratti ^a, Jim Simpson ^a,^*

PMCID: PMC2960970 PMID: 21202100

Abstract

In the title compound, C₄HBr₃S, there are two essentially planar molecules in the asymmetric unit. In the crystal structure, bifurcated C—H⋯Br hydrogen bonds link the molecules into chains. Weak Br⋯Br interactions [Br⋯Br = 3.634 (4)–3.691 (4) Å] then lead to undulating sheets in the bc plane.

Related literature

For related polybromothiophene structures, see: Helmholdt et al. (2007 ▶); Murakami et al. (2002 ▶); Xie et al. (1997 ▶, 1998 ▶). For information on halogen⋯halogen contacts, see: Pedireddi et al. (1994 ▶). For details of the Cambridge Structural Database, see: Allen (2002 ▶).

Experimental

Crystal data

C₄HBr₃S
M _r = 320.84
Orthorhombic,
a = 12.4529 (11) Å
b = 3.9724 (4) Å
c = 28.846 (3) Å
V = 1426.9 (2) Å³
Z = 8
Mo Kα radiation
μ = 17.14 mm⁻¹
T = 91 (2) K
0.17 × 0.06 × 0.02 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2006 ▶) T _min = 0.434, T _max = 0.710
12082 measured reflections
2163 independent reflections
1852 reflections with I > 2σ(I)
R _int = 0.092
θ_max = 23.7°

Refinement

R[F ² > 2σ(F ²)] = 0.061
wR(F ²) = 0.172
S = 0.86
2163 reflections
109 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 3.39 e Å⁻³
Δρ_min = −1.30 e Å⁻³
Absolute structure: Flack (1983 ▶), 1050 Friedel pairs
Flack parameter: 0.11 (6)

Data collection: APEX2 (Bruker 2006 ▶); cell refinement: APEX2 and SAINT (Bruker 2006 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶) and TITAN (Hunter & Simpson, 1999 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶) and TITAN; molecular graphics: ORTEP-3 (Farrugia, 1997 ▶) and Mercury (Macrae et al., 2006 ▶); software used to prepare material for publication: SHELXL97, enCIFer (Allen et al., 2004 ▶) and PLATON (Spek, 2003 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808006600/hb2706sup1.cif

e-64-0o709-sup1.cif^{(14KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808006600/hb2706Isup2.hkl

e-64-0o709-Isup2.hkl^{(106.4KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C1A—H1A⋯Br3Aⁱ	0.95	3.04	3.89 (3)	149
C1A—H1A⋯Br4Aⁱ	0.95	2.96	3.68 (3)	134
C1B—H1B⋯Br3Bⁱⁱ	0.95	2.93	3.79 (3)	151
C1B—H1B⋯Br4Bⁱⁱ	0.95	2.97	3.66 (2)	131

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Symmetry codes: (i) Inline graphic ; (ii) .

Acknowledgments

This work was supported by grant No UOO-X0404 from the New Economy Research Fund of the New Zealand Foundation for Research Science and Technology. We also thank the University of Otago for the purchase of the diffractometer.

supplementary crystallographic information

Comment

Brominated thiophenes are very important intermediates in the construction of thiophene oligomers and polymers for use in optoelectronics. In some cases, it is important to have one or two α-positions free for further oxidative coupling. The 2,3,4-tribromo derivative is not easy to access, as the 2- and 5-positions are normally substituted first, and so it is normally synthesized via debromination from tetrabromothiophene (Xie et al., 1998).

The asymmetric unit of the title compound, (I), C₈H₂Br₆S₂, consists of two discrete tribromothiophene molecules A & B (Fig. 1). Each molecule is essentially planar with r.m.s. deviations from the mean planes through all non-hydrogen atoms of 0.0194 and 0.0286 Å for A and B respectively. The dihedral angle between the A and B ring planes is 0.9 (4)° but they are well separated with a centroid to centroid distance of 6.3 Å.

In the crystal of (I) bifurcated C—H···Br hydrogen bonds (Table 1) form chains of like molecules that pack in an obverse fashion along a. The structure is further stabilized by an extensive network of weak Br···Br interactions with Br···Br distances in the range 3.634 (4)Å (Br3A···Br2Bⁱ, i = 1 - x, 1 - y, -1/2 + z; θ₁ = 156.7° and θ₂ = 117.5°) (Pedireddi et al., 1994) to 3.691 (4)Å (Br3A···Br2Aⁱⁱ ii = -1/2 + x, 1/2 - y, z; θ₁ = 161.8° and θ₂ = 84.7°). These contacts link the chains of molecules into undulating sheets in the bc plane (Fig. 2).

Experimental

2,3,4-Tribromothiophene, prepared by the method of Xie et al. (1998), was dissolved in methanol. Colourless plates of (I) were grown by slow diffusion of water into the solution.