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

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

doi:10.1107/S1600536811023476

. 2011 Jun 25;67(Pt 7):o1814–o1815. doi: 10.1107/S1600536811023476

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

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

PMCID: PMC3152130 PMID: 21837184

Abstract

In the title salt, C₃₆H₄₈N₄ ²⁺·2Br⁻·H₂O, the central benzene ring makes dihedral angles of 84.77 (9) and 69.92 (7)° with the adjacent imidazole rings. In the crystal, one of the heptyl groups is disordered over two sets of sites with an occupancy ratio of 0.474 (5):0.526 (5). In the crystal, the cations, anions and water molecules are connected via intermolecular O—H⋯Br, C—H⋯Br and C—H⋯O hydrogen bonds, forming a three-dimensional network.

Related literature

For details and applications of N-heterocyclic carbenes (NHCs), see: Winkelmann & Navarro (2010 ▶); Kascatan-Nebioglu et al. (2007 ▶); Teyssot et al. (2009 ▶); Herrmann et al. (1995 ▶); Choi et al. (2001 ▶); Kumar & Kumar (2009 ▶). For the stability of the temperature controller used in the data collection, see: Cosier & Glazer (1986 ▶).

Experimental

Crystal data

C₃₆H₄₈N₄ ²⁺·2Br⁻·H₂O
M _r = 714.62
Triclinic,
a = 8.8494 (1) Å
b = 14.7170 (3) Å
c = 16.0838 (2) Å
α = 115.705 (1)°
β = 105.380 (1)°
γ = 91.946 (1)°
V = 1792.83 (5) Å³
Z = 2
Mo Kα radiation
μ = 2.29 mm⁻¹
T = 100 K
0.39 × 0.18 × 0.16 mm

Data collection

Bruker SMART APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2009 ▶) T _min = 0.469, T _max = 0.715
50860 measured reflections
12945 independent reflections
10091 reflections with I > 2σ(I)
R _int = 0.027

Refinement

R[F ² > 2σ(F ²)] = 0.032
wR(F ²) = 0.077
S = 1.02
12945 reflections
442 parameters
9 restraints
H atoms treated by a mixture of independent and constrained refinement
Δρ_max = 0.84 e Å⁻³
Δρ_min = −0.75 e Å⁻³

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/S1600536811023476/is2732sup1.cif

e-67-o1814-sup1.cif^{(34.2KB, cif)}

Structure factors: contains datablock(s) I. DOI: 10.1107/S1600536811023476/is2732Isup2.hkl

e-67-o1814-Isup2.hkl^{(620.1KB, 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
O1W—H1W1⋯Br1	0.84 (3)	2.50 (3)	3.3271 (17)	169 (2)
O1W—H2W1⋯Br2	0.79 (3)	2.54 (3)	3.3280 (14)	177 (3)
C1—H1A⋯Br1ⁱ	0.95	2.80	3.6093 (15)	144
C3—H3A⋯Br2ⁱⁱ	0.95	2.92	3.7866 (16)	153
C5—H5A⋯Br2ⁱⁱⁱ	0.95	2.89	3.8162 (17)	167
C8—H8A⋯Br2^iv	0.99	2.93	3.9117 (16)	172
C15—H15A⋯Br2^iv	0.99	2.72	3.6809 (19)	165
C15—H15B⋯Br1^iv	0.99	2.80	3.7842 (15)	170
C18—H18A⋯O1W^v	0.95	2.46	3.187 (2)	133
C20—H20A⋯Br2	0.95	2.76	3.6602 (16)	158
C22—H22A⋯Br1ⁱ	0.95	2.70	3.5577 (15)	150
C23—H23A⋯Br2ⁱ	0.99	2.89	3.7836 (14)	151
C23—H23B⋯Br2ⁱⁱ	0.99	2.81	3.7285 (17)	154

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

Acknowledgments

RAH thanks Universiti Sains Malaysia (USM) for the FRGS fund (203/PKIMIA/671115), short term grant (304/PKIMIA639001), and RU grants (1001/PKIMIA/811157) and (1001/PKIMIA/823082). MAI is grateful to (IPS) USM for financial support [fellowship: USM.IPS/JWT/1/19 (JLD 6)]. HKF and MH thank the Malaysian Government and UUSM for the Research University Grant No. 1001/PFIZIK/811160. MH thanks USM for a post-doctoral research fellowship.

supplementary crystallographic information

Comment

N-Heterocyclic Carbenes (NHCs) is a versatile class of ligands, which have widespread applications in organometallic chemistry (Winkelmann & Navarro, 2010). Metal complexes of NHCs have proven to be potential antimicrobial (Kascatan-Nebioglu et al., 2007) and anticancer (Teyssot et al., 2009) agents. Notably, NHCs also exhibit excellent catalytical activity for Heck and Suzuki coupling reactions (Herrmann et al., 1995) and Metathesis Cross-Coupling reactions (Choi et al., 2001). Benzimidazole-based NHCs of similar structures and their metal complexes are now known to be effective catalysts for the cross coupling reactions of different alcohols and ratiometric sensing (Kumar & Kumar, 2009).

The asymmetric unit of the title compound, (Fig. 1), consists of a 3,3'-[1,2-phenylenebis(methylene)]bis(1-heptylbenzimidazolium) cation, two bromine anions and one water molecule. One of the heptyl group is disordered over two sets of sites, with an occupancy ratio of 0.474 (5):0.526 (5). The central benzene (C9–C14) ring makes dihedral angles of 84.77 (9) and 69.92 (7)° with the adjacent imidazole (N1/N2/C1/C2/C7) and (N3/N4/C16/C21/C22) rings, respectively.

In the crystal structure (Fig. 2), the cations, anions and water molecules are linked together via intermolecular O1W—H1W1···Br1, O1W—H2W1···Br2, C1—H1A···Br1, C3—H3A···Br2, C5—H5A···Br2, C8—H8A···Br2, C15—H15A···Br2, C15—H15B···Br1, C18—H18A···O1W, C20—H20A···Br2, C22—H22A···Br1, C23—H23A···Br2 and C23—H23B···Br2 (Table 1) hydrogen bonds, forming a three-dimensional network.

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 minutes. 1-bromoheptane (3.14 ml, 20 mmol) was added drop-wise in this consistently stirred mixture with further stirring for 2 h at the 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 afford N-heptylbenzimidazole (1) as a thick yellowish fluid (3.87 g, 89.6%). Furthermore, a mixture of 1 (2.16 g, 10 mmol) and 1,2-bis(bromomethyl)benzene (1.32 g, 5 mmol) in dioxane (30 ml) was refluxed at 90 °C for 12 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 (1.72 g, 49.4%). Hot (saturated) solution of 2.2Br in deuterated DMSO (0.5 ml) was cooled to room temperature in NMR tube overnight to get single (prismatic) crystals suitable for X-ray diffraction study.