organic compounds
4-Bromo-2-(5-bromothiophen-2-yl)-1-[(5-bromothiophen-2-yl)methyl]-5,6-dimethyl-1H-benzimidazole
aDepartment of Chemistry, State University of New York-College at Geneseo, 1 College Circle, Geneseo, NY 14454, USA
*Correspondence e-mail: geiger@geneseo.edu
The title compound, C18H13Br3N2S2, was obtained via the reaction of N-bromosuccinamide with 5,6-dimethyl-2-(thiophen-2-yl)-1-[(thiophen-2-yl)methyl]-1H-benzimidazole. The compound exhibits rotational disorder of the 5-bromothiophen-2-yl substituent with a refined major:minor occupancy ratio of 0.876 (7):0.124 (7). The 5-bromothiophen-2-yl mean plane is canted to the benzimidazole plane by 20.0 (4) and 21 (4)° in the major and minor components, respectively. In the crystal, weak C—H⋯N interactions link the molecules into infinite C(7) chains along the 21 axes.
CCDC reference: 992876
Related literature
Bromination of thiophenes using N-bromosuccinamide has been reported by Arsenyan et al. (2010). For the structure of 5,6-dimethylbenzimidazole, see: Lee & Scheidt (1986). For the structure of 2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzimidazole, see: Geiger et al. (2012). For the 5-chloro derivative, see: Geiger & Nellist (2013a), for the 6-chloro derivative, see: Geiger & Nellist (2013b) and for the 6-bromo derivative, see: Geiger & Destefano (2012). For a discussion of the biological activity of benzimidazole derivatives, see: López-Rodríguez et al. (1999); Horton et al. (2003).
Experimental
Crystal data
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Data collection: APEX2 (Bruker, 2013); cell SAINT (Bruker, 2013); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2013); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).
Supporting information
CCDC reference: 992876
10.1107/S160053681400628X/rz5112sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: 10.1107/S160053681400628X/rz5112Isup2.hkl
Supporting information file. DOI: 10.1107/S160053681400628X/rz5112Isup3.mol
Supporting information file. DOI: 10.1107/S160053681400628X/rz5112Isup4.cml
The title compound was prepared by a photoinitiated reaction of N-bromosuccimide (1.10 g, 6.18 mmole) and 5,6-dimethyl-2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H-benzimidazole (0.864 g, 2.66 mmole) in refluxing carbon tetrachloride (20 mL). Based on GC—MS results, the material isolated was a mixture of a mono-, di- and tri-brominated components. Attempts to separate the components by
or recrystallization were unsuccessful. Based on a comparison of a 1H NMR spectrum of the product mixture and simulated spectra of mono-, di- and tri-brominated products, the reaction product mixture is approximately 50% tri-brominated species. Single crystals of the tribromo component (the title compound) were obtained by slow vapor diffusion of hexanes into a chloroform solution of the product mixture.During the later stages of
it became obvious that the molecule exhibited rotational disorder about the 5-bromothiophen-2-yl substituent. The disorder was successfully modeled using the metrics of the major component to define the minor component. Similarity restraints were used for the bond distances using SAME and anisotropic displacement parameters of the minor component atoms were constrained to those of the major component using EADP. The structure converged with a refined major:minor occupancy ratio of 0.876 (7):0.124 (7). All hydrogen atoms were observed in difference Fourier fourier maps. The H atoms were refined using a riding model with a C—H distance of 0.99 Å for the methylene carbon atoms, 0.98 Å for the methyl carbon atoms and 0.95 Å for the phenyl and thiophene carbon atoms. The methyl C—H hydrogen atom isotropic displacement parameters were set using the approximation Uiso(H) = 1.5Ueq(C). All other C—H hydrogen atom isotropic displacement parameters were set using the approximation Uiso(H) = 1.2Ueq(C).Data collection: APEX2 (Bruker, 2013); cell
SAINT (Bruker, 2013); data reduction: SAINT (Bruker, 2013); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2013 (Sheldrick, 2013); molecular graphics: PLATON (Spek, 2009) and Mercury (Macrae et al., 2008); software used to prepare material for publication: publCIF (Westrip, 2010).C18H13Br3N2S2 | F(000) = 1088 |
Mr = 561.15 | Dx = 1.934 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 4288 reflections |
a = 13.6796 (13) Å | θ = 2.5–25.0° |
b = 9.6144 (8) Å | µ = 6.50 mm−1 |
c = 14.8093 (15) Å | T = 200 K |
β = 98.305 (3)° | Plate, clear colourless |
V = 1927.3 (3) Å3 | 0.60 × 0.40 × 0.10 mm |
Z = 4 |
Bruker SMART X2S benchtop diffractometer | 3561 independent reflections |
Radiation source: sealed microfocus tube | 2810 reflections with I > 2σ(I) |
Doubly curved silicon crystal monochromator | Rint = 0.036 |
Detector resolution: 8.3330 pixels mm-1 | θmax = 25.5°, θmin = 1.9° |
ω scans | h = −16→16 |
Absorption correction: multi-scan (SADABS; Bruker, 2013) | k = −11→11 |
Tmin = 0.35, Tmax = 0.56 | l = −17→11 |
12301 measured reflections |
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)] = 0.056 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.179 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0876P)2 + 13.3538P] where P = (Fo2 + 2Fc2)/3 |
3561 reflections | (Δ/σ)max < 0.001 |
247 parameters | Δρmax = 0.87 e Å−3 |
16 restraints | Δρmin = −1.90 e Å−3 |
C18H13Br3N2S2 | V = 1927.3 (3) Å3 |
Mr = 561.15 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 13.6796 (13) Å | µ = 6.50 mm−1 |
b = 9.6144 (8) Å | T = 200 K |
c = 14.8093 (15) Å | 0.60 × 0.40 × 0.10 mm |
β = 98.305 (3)° |
Bruker SMART X2S benchtop diffractometer | 3561 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2013) | 2810 reflections with I > 2σ(I) |
Tmin = 0.35, Tmax = 0.56 | Rint = 0.036 |
12301 measured reflections |
R[F2 > 2σ(F2)] = 0.056 | 16 restraints |
wR(F2) = 0.179 | H-atom parameters constrained |
S = 1.06 | w = 1/[σ2(Fo2) + (0.0876P)2 + 13.3538P] where P = (Fo2 + 2Fc2)/3 |
3561 reflections | Δρmax = 0.87 e Å−3 |
247 parameters | Δρmin = −1.90 e Å−3 |
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. |
x | y | z | Uiso*/Ueq | Occ. (<1) | |
C1 | 0.6567 (5) | 0.4489 (7) | 0.0616 (5) | 0.0297 (15) | |
C2 | 0.5806 (5) | 0.3747 (7) | 0.0935 (5) | 0.0291 (15) | |
C3 | 0.5164 (5) | 0.2979 (7) | 0.0299 (5) | 0.0328 (16) | |
C4 | 0.5271 (6) | 0.2972 (7) | −0.0623 (5) | 0.0345 (17) | |
C5 | 0.6069 (6) | 0.3752 (9) | −0.0909 (5) | 0.0388 (18) | |
C6 | 0.6698 (6) | 0.4519 (8) | −0.0296 (5) | 0.0341 (16) | |
H6 | 0.7211 | 0.5058 | −0.0491 | 0.041* | |
C41 | 0.4614 (7) | 0.2091 (9) | −0.1300 (6) | 0.048 (2) | |
H41A | 0.4983 | 0.1275 | −0.146 | 0.071* | |
H41B | 0.4395 | 0.2637 | −0.185 | 0.071* | |
H41C | 0.4037 | 0.1787 | −0.1029 | 0.071* | |
C51 | 0.6220 (7) | 0.3744 (12) | −0.1887 (5) | 0.055 (2) | |
H51A | 0.6732 | 0.442 | −0.1979 | 0.083* | |
H51B | 0.56 | 0.3992 | −0.2271 | 0.083* | |
H51C | 0.6426 | 0.2813 | −0.2053 | 0.083* | |
Br3 | 0.41595 (6) | 0.19379 (9) | 0.07516 (6) | 0.0461 (3) | |
N1 | 0.7086 (4) | 0.5125 (6) | 0.1385 (4) | 0.0291 (13) | |
C7 | 0.6621 (5) | 0.4710 (7) | 0.2112 (5) | 0.0282 (15) | |
N2 | 0.5860 (4) | 0.3888 (6) | 0.1866 (4) | 0.0284 (13) | |
C8 | 0.6925 (12) | 0.5165 (15) | 0.3059 (6) | 0.0252 (18) | 0.876 (7) |
C9 | 0.7801 (11) | 0.5660 (14) | 0.3497 (7) | 0.031 (2) | 0.876 (7) |
H9 | 0.8365 | 0.5803 | 0.3203 | 0.037* | 0.876 (7) |
C10 | 0.7787 (8) | 0.5937 (9) | 0.4431 (6) | 0.030 (2) | 0.876 (7) |
H10 | 0.8334 | 0.6288 | 0.4835 | 0.036* | 0.876 (7) |
C11 | 0.6903 (8) | 0.5643 (9) | 0.4674 (5) | 0.032 (2) | 0.876 (7) |
S1 | 0.6069 (8) | 0.5018 (9) | 0.3795 (3) | 0.0336 (12) | 0.876 (7) |
Br1 | 0.65371 (11) | 0.5955 (3) | 0.58337 (8) | 0.0544 (5) | 0.876 (7) |
C80 | 0.685 (8) | 0.502 (10) | 0.302 (3) | 0.0252 (18) | 0.124 (7) |
C90 | 0.775 (7) | 0.543 (11) | 0.347 (4) | 0.031 (2) | 0.124 (7) |
H90 | 0.8304 | 0.5603 | 0.3166 | 0.037* | 0.124 (7) |
C100 | 0.777 (5) | 0.557 (9) | 0.442 (4) | 0.030 (2) | 0.124 (7) |
H100 | 0.8338 | 0.5836 | 0.4829 | 0.036* | 0.124 (7) |
C110 | 0.689 (4) | 0.529 (7) | 0.4662 (19) | 0.032 (2) | 0.124 (7) |
S10 | 0.602 (6) | 0.480 (8) | 0.377 (2) | 0.0336 (12) | 0.124 (7) |
Br10 | 0.6580 (9) | 0.530 (2) | 0.5862 (6) | 0.0544 (5) | 0.124 (7) |
C12 | 0.7869 (5) | 0.6148 (7) | 0.1354 (5) | 0.0312 (16) | |
H12A | 0.7851 | 0.6824 | 0.1856 | 0.037* | |
H12B | 0.7734 | 0.6666 | 0.0772 | 0.037* | |
C13 | 0.8884 (5) | 0.5541 (7) | 0.1435 (4) | 0.0267 (15) | |
C14 | 0.9740 (6) | 0.6115 (9) | 0.1828 (5) | 0.0399 (18) | |
H14 | 0.9773 | 0.6971 | 0.2151 | 0.048* | |
C15 | 1.0593 (6) | 0.5319 (9) | 0.1713 (6) | 0.0426 (19) | |
H15 | 1.1251 | 0.5573 | 0.195 | 0.051* | |
C16 | 1.0341 (6) | 0.4152 (8) | 0.1220 (5) | 0.0387 (18) | |
S2 | 0.90879 (16) | 0.3984 (2) | 0.09103 (14) | 0.0396 (5) | |
Br2 | 1.11809 (9) | 0.28087 (11) | 0.08705 (7) | 0.0637 (4) |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.036 (4) | 0.020 (3) | 0.032 (4) | 0.003 (3) | 0.005 (3) | 0.001 (3) |
C2 | 0.034 (4) | 0.021 (3) | 0.032 (4) | 0.009 (3) | 0.003 (3) | 0.003 (3) |
C3 | 0.033 (4) | 0.025 (4) | 0.037 (4) | 0.003 (3) | −0.005 (3) | 0.003 (3) |
C4 | 0.037 (4) | 0.029 (4) | 0.035 (4) | 0.015 (3) | −0.004 (3) | −0.001 (3) |
C5 | 0.040 (4) | 0.046 (5) | 0.029 (4) | 0.019 (4) | 0.002 (3) | 0.004 (3) |
C6 | 0.038 (4) | 0.035 (4) | 0.029 (4) | 0.005 (3) | 0.007 (3) | 0.002 (3) |
C41 | 0.049 (5) | 0.050 (5) | 0.039 (4) | 0.007 (4) | −0.010 (4) | −0.009 (4) |
C51 | 0.049 (5) | 0.086 (7) | 0.030 (4) | 0.023 (5) | 0.000 (4) | 0.001 (4) |
Br3 | 0.0447 (5) | 0.0381 (5) | 0.0518 (5) | −0.0119 (4) | −0.0055 (4) | 0.0037 (4) |
N1 | 0.034 (3) | 0.026 (3) | 0.027 (3) | −0.006 (3) | 0.004 (2) | −0.002 (2) |
C7 | 0.033 (4) | 0.021 (3) | 0.031 (4) | 0.002 (3) | 0.006 (3) | 0.001 (3) |
N2 | 0.031 (3) | 0.021 (3) | 0.032 (3) | −0.002 (2) | 0.002 (2) | 0.001 (2) |
C8 | 0.030 (5) | 0.017 (4) | 0.029 (3) | −0.003 (3) | 0.007 (3) | 0.002 (3) |
C9 | 0.030 (4) | 0.029 (6) | 0.033 (4) | −0.007 (4) | 0.005 (3) | −0.001 (3) |
C10 | 0.036 (4) | 0.023 (6) | 0.029 (4) | −0.006 (4) | 0.000 (3) | 0.001 (4) |
C11 | 0.050 (5) | 0.019 (5) | 0.027 (4) | −0.002 (4) | 0.006 (3) | 0.003 (3) |
S1 | 0.0328 (17) | 0.038 (4) | 0.0307 (10) | −0.0099 (19) | 0.0077 (9) | −0.0001 (11) |
Br1 | 0.0781 (7) | 0.0542 (15) | 0.0354 (5) | −0.0216 (8) | 0.0230 (5) | −0.0079 (6) |
C80 | 0.030 (5) | 0.017 (4) | 0.029 (3) | −0.003 (3) | 0.007 (3) | 0.002 (3) |
C90 | 0.030 (4) | 0.029 (6) | 0.033 (4) | −0.007 (4) | 0.005 (3) | −0.001 (3) |
C100 | 0.036 (4) | 0.023 (6) | 0.029 (4) | −0.006 (4) | 0.000 (3) | 0.001 (4) |
C110 | 0.050 (5) | 0.019 (5) | 0.027 (4) | −0.002 (4) | 0.006 (3) | 0.003 (3) |
S10 | 0.0328 (17) | 0.038 (4) | 0.0307 (10) | −0.0099 (19) | 0.0077 (9) | −0.0001 (11) |
Br10 | 0.0781 (7) | 0.0542 (15) | 0.0354 (5) | −0.0216 (8) | 0.0230 (5) | −0.0079 (6) |
C12 | 0.039 (4) | 0.025 (3) | 0.031 (4) | −0.006 (3) | 0.008 (3) | 0.003 (3) |
C13 | 0.035 (4) | 0.023 (3) | 0.024 (3) | 0.001 (3) | 0.009 (3) | 0.001 (3) |
C14 | 0.044 (5) | 0.037 (4) | 0.039 (4) | 0.000 (4) | 0.007 (4) | −0.006 (3) |
C15 | 0.032 (4) | 0.052 (5) | 0.046 (5) | 0.000 (4) | 0.011 (3) | −0.002 (4) |
C16 | 0.041 (5) | 0.042 (4) | 0.036 (4) | 0.009 (4) | 0.014 (3) | 0.005 (3) |
S2 | 0.0445 (11) | 0.0302 (10) | 0.0444 (11) | 0.0010 (9) | 0.0071 (9) | −0.0083 (8) |
Br2 | 0.0795 (7) | 0.0563 (6) | 0.0619 (6) | 0.0217 (5) | 0.0329 (5) | 0.0114 (5) |
C1—C6 | 1.389 (10) | C9—C10 | 1.410 (10) |
C1—N1 | 1.393 (9) | C9—H9 | 0.95 |
C1—C2 | 1.399 (10) | C10—C11 | 1.341 (11) |
C2—N2 | 1.376 (9) | C10—H10 | 0.95 |
C2—C3 | 1.402 (10) | C11—S1 | 1.711 (8) |
C3—C4 | 1.394 (11) | C11—Br1 | 1.882 (8) |
C3—Br3 | 1.899 (8) | C80—C90 | 1.36 (2) |
C4—C5 | 1.439 (12) | C80—S10 | 1.717 (19) |
C4—C41 | 1.506 (11) | C90—C100 | 1.41 (2) |
C5—C6 | 1.372 (11) | C90—H90 | 0.95 |
C5—C51 | 1.492 (11) | C100—C110 | 1.34 (2) |
C6—H6 | 0.95 | C100—H100 | 0.95 |
C41—H41A | 0.98 | C110—S10 | 1.710 (19) |
C41—H41B | 0.98 | C110—Br10 | 1.884 (18) |
C41—H41C | 0.98 | C12—C13 | 1.494 (10) |
C51—H51A | 0.98 | C12—H12A | 0.99 |
C51—H51B | 0.98 | C12—H12B | 0.99 |
C51—H51C | 0.98 | C13—C14 | 1.349 (11) |
N1—C7 | 1.387 (9) | C13—S2 | 1.728 (7) |
N1—C12 | 1.460 (9) | C14—C15 | 1.426 (11) |
C7—N2 | 1.317 (9) | C14—H14 | 0.95 |
C7—C80 | 1.37 (5) | C15—C16 | 1.356 (12) |
C7—C8 | 1.470 (11) | C15—H15 | 0.95 |
C8—C9 | 1.363 (10) | C16—S2 | 1.717 (8) |
C8—S1 | 1.717 (7) | C16—Br2 | 1.852 (8) |
C6—C1—N1 | 131.5 (7) | C8—C9—C10 | 113.4 (7) |
C6—C1—C2 | 123.1 (7) | C8—C9—H9 | 123.3 |
N1—C1—C2 | 105.3 (6) | C10—C9—H9 | 123.3 |
N2—C2—C1 | 110.7 (6) | C11—C10—C9 | 111.3 (7) |
N2—C2—C3 | 131.5 (7) | C11—C10—H10 | 124.4 |
C1—C2—C3 | 117.8 (7) | C9—C10—H10 | 124.4 |
C4—C3—C2 | 121.1 (7) | C10—C11—S1 | 113.5 (6) |
C4—C3—Br3 | 121.7 (6) | C10—C11—Br1 | 125.5 (6) |
C2—C3—Br3 | 117.1 (5) | S1—C11—Br1 | 120.9 (5) |
C3—C4—C5 | 118.5 (7) | C11—S1—C8 | 90.7 (4) |
C3—C4—C41 | 121.2 (8) | C90—C80—C7 | 127 (6) |
C5—C4—C41 | 120.2 (7) | C90—C80—S10 | 111.0 (17) |
C6—C5—C4 | 121.0 (7) | C7—C80—S10 | 122 (6) |
C6—C5—C51 | 118.9 (8) | C80—C90—C100 | 114 (2) |
C4—C5—C51 | 120.0 (8) | C80—C90—H90 | 123.2 |
C5—C6—C1 | 118.4 (7) | C100—C90—H90 | 123.2 |
C5—C6—H6 | 120.8 | C110—C100—C90 | 111 (2) |
C1—C6—H6 | 120.8 | C110—C100—H100 | 124.5 |
C4—C41—H41A | 109.5 | C90—C100—H100 | 124.5 |
C4—C41—H41B | 109.5 | C100—C110—S10 | 113.7 (16) |
H41A—C41—H41B | 109.5 | C100—C110—Br10 | 126 (2) |
C4—C41—H41C | 109.5 | S10—C110—Br10 | 120 (2) |
H41A—C41—H41C | 109.5 | C110—S10—C80 | 90.7 (13) |
H41B—C41—H41C | 109.5 | N1—C12—C13 | 114.3 (6) |
C5—C51—H51A | 109.5 | N1—C12—H12A | 108.7 |
C5—C51—H51B | 109.5 | C13—C12—H12A | 108.7 |
H51A—C51—H51B | 109.5 | N1—C12—H12B | 108.7 |
C5—C51—H51C | 109.5 | C13—C12—H12B | 108.7 |
H51A—C51—H51C | 109.5 | H12A—C12—H12B | 107.6 |
H51B—C51—H51C | 109.5 | C14—C13—C12 | 127.9 (7) |
C7—N1—C1 | 105.8 (6) | C14—C13—S2 | 111.2 (6) |
C7—N1—C12 | 129.7 (6) | C12—C13—S2 | 120.7 (5) |
C1—N1—C12 | 124.1 (6) | C13—C14—C15 | 113.8 (7) |
N2—C7—C80 | 118 (4) | C13—C14—H14 | 123.1 |
N2—C7—N1 | 113.0 (6) | C15—C14—H14 | 123.1 |
C80—C7—N1 | 129 (4) | C16—C15—C14 | 111.1 (7) |
N2—C7—C8 | 123.1 (7) | C16—C15—H15 | 124.5 |
N1—C7—C8 | 123.9 (7) | C14—C15—H15 | 124.5 |
C7—N2—C2 | 105.2 (6) | C15—C16—S2 | 112.9 (6) |
C9—C8—C7 | 131.8 (10) | C15—C16—Br2 | 127.4 (6) |
C9—C8—S1 | 111.1 (6) | S2—C16—Br2 | 119.7 (5) |
C7—C8—S1 | 117.1 (8) | C16—S2—C13 | 91.1 (4) |
D—H···A | D—H | H···A | D···A | D—H···A |
C14—H14···N2i | 0.95 | 2.57 | 3.461 (10) | 156 |
Symmetry code: (i) −x+3/2, y+1/2, −z+1/2. |
D—H···A | D—H | H···A | D···A | D—H···A |
C14—H14···N2i | 0.95 | 2.57 | 3.461 (10) | 155.5 |
Symmetry code: (i) −x+3/2, y+1/2, −z+1/2. |
Acknowledgements
This work was supported by a Congressionally directed grant from the US Department of Education (grant No. P116Z100020) for the X-ray diffractometer and a grant from the Geneseo Foundation.
References
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Benzimidazole derivatives have numerous pharmacological uses. Examples include inhibitors of serotonin activated neurotransmission drugs (López-Rodríguez et al., 1999) and antiarrhythmic, antihistamine, antiulcer, anticancer, fungicidal, and anthelmintical drugs (Horton et al., 2003). The title compound was prepared as part of our efforts to characterize benzimidazole analogues with thiophene substitutents (Geiger & Nellist, 2013a; Geiger & Nellist, 2013b; Geiger & Destefano, 2012; Geiger et al., 2012).
The title compound was prepared serendipitously during the attempted bromination of the methyl substituents of 5,6-dimethyl-2-(thiophen-2-yl)-1-(thiophen-2-ylmethyl)-1H- benzimidazole. Bromination of the positions adjacent to the sulfur atom in thiophene and thiophene derivatives with N-bromosuccinamide (NBS)using ultrasonic irradiation has been reported by Arsenyan et al. (2010). In all cases, bromination occurs at sites adjacent to the sulfur atom. Based on this observation, it is not surprising that the two thiophene groups are brominated in the title complex. However, bromination of the benzene ring using NBS is not expected, as free radical bromination is expected to occur at the benzylic positions.
Compound I crystallizes with one molecule in the asymmetric unit. A perspective view of the molecule with the atom-labeling scheme is shown in figure 1. The benzimidazole ring system is essentially planar. The largest deviation from planarity is 0.017 (6) Å for C5. The 2-(5-bromothiophen-2-yl) plane is canted 20.0 (4)o and 21 (4)o to the benzimidazole plane in the major and minor disorder components, respectively.
The extended structure exhibits chains along the 21 screw axes formed by weak intermolecular C—H···N hydrogen bonds (Table 1) involving one of the 5-bromothiophen-2-ylmethyl hydrogen atoms (H14) and the unsubstitued benzimidazole nitrogen atom (N2). The result is infinite C(7) chains. Figure 2 displays a packing diagram exhibiting the chains parallel to [0 1 0].
An additional close contact between bromine atoms on molecules related by the glide plane is observed. The Br2···Br10 distance is 3.041 (19) Å (Br10 is part of the minor component of the disordered 5-bromothiophen-2-yl substituent.) The Br2···Br1 (Br1 is the bromine of the major component) distance is 3.653 (3) Å.