3,3′-[1,2-Phenyl­enebis(methyl­ene)]bis­(1-ethyl­benzimidazolium) dibromide

Rosenani A Haque; Muhammad Adnan Iqbal; Srinivasa Budagumpi; Madhukar Hemamalini; Hoong-Kun Fun

doi:10.1107/S1600536812002802

. 2012 Feb 4;68(Pt 3):o573. doi: 10.1107/S1600536812002802

3,3′-[1,2-Phenylenebis(methylene)]bis(1-ethylbenzimidazolium) dibromide

Rosenani A Haque ^a, Muhammad Adnan Iqbal ^a, Srinivasa Budagumpi ^a, Madhukar Hemamalini ^b, Hoong-Kun Fun ^b,^*,^‡

PMCID: PMC3297300 PMID: 22412490

Abstract

In the title molecular salt, C₂₆H₂₈N₄ ²⁺·2Br⁻, the central benzene ring makes dihedral angles of 76.75 (11) and 82.40 (10)° with the pendant benzimidazole rings. The corresponding angle between the benzimidazole rings is 57.03 (9)°. In the crystal, the cations and anions are linked via C—H⋯Br hydrogen bonds, forming sheets lying parallel to the bc plane. The crystal structure also features weak C—H⋯π interactions.

Related literature

For background to the biological activities of benzimidazole compounds, see: Mohan et al. (2011 ▶).

Experimental

Crystal data

C₂₆H₂₈N₄ ²⁺·2Br⁻
M _r = 556.34
Monoclinic,
a = 9.7093 (7) Å
b = 35.796 (3) Å
c = 8.0340 (6) Å
β = 118.230 (1)°
V = 2460.1 (3) Å³
Z = 4
Mo Kα radiation
μ = 3.32 mm⁻¹
T = 296 K
0.45 × 0.32 × 0.23 mm

Data collection

Bruker APEXII DUO CCD diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.318, T _max = 0.516
16606 measured reflections
8158 independent reflections
6244 reflections with I > 2σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.033
wR(F ²) = 0.080
S = 1.02
8158 reflections
291 parameters
2 restraints
H-atom parameters constrained
Δρ_max = 0.71 e Å⁻³
Δρ_min = −0.28 e Å⁻³
Absolute structure: Flack (1983 ▶), 3727 Friedel pairs
Flack parameter: 0.009 (6)

Data collection: APEX2 (Bruker, 2009 ▶); cell refinement: SAINT (Bruker, 2009 ▶); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL and PLATON (Spek, 2009 ▶).

Supplementary Material

Crystal structure: contains datablock(s) global, I. DOI: 10.1107/S1600536812002802/hb6611sup1.cif

e-68-0o573-sup1.cif^{(32KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536812002802/hb6611Isup2.hkl

e-68-0o573-Isup2.hkl^{(391.1KB, hkl)}

Supplementary material file. DOI: 10.1107/S1600536812002802/hb6611Isup3.cml

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

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

Cg4 is the centroid of the C11–C16 ring.

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C9—H9A⋯Br2	0.93	2.76	3.610 (2)	152
C10—H10A⋯Br1ⁱ	0.97	2.92	3.884 (2)	171
C10—H10B⋯Br2	0.97	2.91	3.820 (2)	156
C15—H15A⋯Br2ⁱⁱ	0.93	2.80	3.700 (3)	163
C17—H17B⋯Br2	0.97	2.78	3.696 (3)	158
C24—H24A⋯Br1	0.93	2.73	3.579 (2)	152
C5—H5A⋯Cg4ⁱⁱⁱ	0.93	2.92	3.630 (3)	135

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

Acknowledgments

RAH thanks Universiti Sains Malaysia (USM) for the Research University grant Nos. 1001/PKIMIA/811157 and 1001/PKIMIA/823082. MAI is grateful to (IPS) USM for financial support [fellowship USM.IPS/JWT/1/19 (JLD 6)] and research attachment fund [P-KM0018/10(R)–308/AIPS/415401]. HKF and MH thank the Malaysian Government and Universiti Sains Malaysia for the Research University grant No. 1001/PFIZIK/811160. MH also thanks Universiti Sains Malaysia for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

Many benzimidazole containing compounds are biologically active (Mohan et al., 2011). As part of our studies in this area, we now describe the title compound, (I).

The central benzene ring (C11–C16) makes dihedral angles of 76.75 (11) and 82.40 (10)° with the adjacent benzimidazole rings (N1,N2/C3–C9) and (N3,N4/C18–C24). The dihedral angle between the benzimidazole rings (N1,N2/C3–C9) and (N1,N2/C3–C9) is 57.03 (9)°. The benzimidazole (N1,N2/C3–C9) and (N3,N4/C18–C24) rings are approximately planar [maximum deviations of 0.020 (3) Å for atom C3 and 0.014 (2) Å for atom N3, respectively].

In the crystal (Fig. 2), the cations and anions are linked via C—H···Br (Table 1) hydrogen bonds, forming two-dimensional networks lying parallel to the the bc-plane. The crystal structure also features weak C—H···π interactions involving the centroid of the phenyl (C11–C16) ring.

Experimental

A mixture of benzimidazole (2.36 g, 20 mmol) and finely ground potassium hydroxide (2.36 g, 30 mmol) in 30 ml of DMSO was stirred at room temperature (27–28 °C) for 30 min. 1-Bromoethane (1.50 ml, 20 mmol) was added drop wise in this consistently stirring mixture and further stirred for 2 h at same temperature, poured into water (300 ml) and was extracted by chloroform (5 × 20 ml). The extract was dried by magnesium sulphate and evaporated under reduced pressure to get N-ethylbenzimidazole as a thick yellowish fluid (2.52 g, 86.30%). Furthermore, a mixture of 1 (1.46 g, 10 mmol) and 1,2-bis(bromomethyl)benzene (1.32 g, 5 mmol) in dioxane (30 ml) was refluxed at 110 °C for 18 h. Desired compound (2.2Br) appeared as beige–colored precipitates in dark brown solution. The mixture was filtered and precipitates were washed by fresh dioxane (3 × 5 ml), dried at room temperature for 24 h, and soft lumps so obtained were ground to fine powder (2.40 g, 86.33%). Saturated solution of 2.2Br in methanol (0.5 ml) was exposed to diethyl ether vapours (vapour diffusion) at room temperature overnight to get colourless blocks of (I).