supplementary materials


HTML versionpdf versioncif file3d viewstructure factorssupplementary materialsCIF check reportsimilar papers Open access

Acta Cryst. (2008). E64, o2086    [ doi:10.1107/S1600536808031863 ]

3,3'-Bis(3-methoxybenzyl)-1,1'-ethylenediimidazolium dibromide

H. M. Lee and C.-Y. Lu

Abstract top

In the title compound, C24H28N4O22+·2Br-, the imidazolium cation is located on an inversion centre. The two imidazole rings are parallel to each other, whereas the imidazole and benzene rings make a dihedral angle of 77.25 (16)°. Nonclassical intermolecular C-H...Br hydrogen bonds link the imidazolium cations and the bromide anions into a three-dimensional network.

Comment top

In the past decade, N-heterocyclic carbenes (NHCs) and their palladium complexes have attracted much interest due to their catalytic activities in C—C coupling reactions (Hillier et al., 2002). The structure of 1,1'-bis(3-methoxybenzyl)-3,3'-methylenediimidazolium dibromide has already been reported (Lee & Chiu, 2004). The structures of other related bis(imidazolium) salts have also been reported (Cheng et al., 2006; Lee et al., 2007).

One of the common methods for the preparation of palladium NHC complexes is a one-pot reaction between an imidazolium salt and a palladium precursor in the presence of base (Lee et al., 2004). By this method, we prepared a palladium bis(NHC) complex from the title compound. Here, we report the crystal structure of the title compound.

The structure of the title compound is shown in Fig. 1. The bis(imidazolium) dication is located on an inversion center, with the two imidazole rings parallel to each other. The imidazole and benzene rings make a dihedral angle of 77.25 (16)°. The bromide anions are involved in intermolecular hydrogen bonds of the type C—H···Br with the imidazolium cations, forming a three-dimensional hydrogen-bonded network (Fig. 2 and Table 1).

Related literature top

For the structure of 1,1'-bis(3-methoxybenzyl)-3,3'-methylenediimidazolium dibromide see: Lee & Chiu (2004). For the structures of other related bis(imidazolium) salts, see: Cheng et al. (2006); Lee et al. (2004); Lee et al. (2007). For a review of N-heterocyclic carbenes, see: Hillier et al. (2002)

Experimental top

The compound was prepared according to the literature procedure (Lee et al., 2004). Suitable crystals were obtained by slow diffusion of diethyl ether into a DMF solution of the compound at room temperature. The average dimensions of the colorless, rod-like crystals are about 0.35 x 0.20 x 0.20 mm.

Refinement top

All hydrogen atoms could have been located in the difference Fourier map; nevertheless, they were all positioned geometrically and refined as riding atoms, with Caryl—H = 0.93, Cmethyl —H = 0.96, Cmethylene—H = 0.97 Å; Uiso(H) = 1.5Ueq(C) for the methyl H atoms and Uiso(H) = 1.2Ueq(C) for all the other H atoms.

Computing details top

Data collection: APEX2 (Bruker, 2004); cell refinement: APEX2 (Bruker, 2004); data reduction: APEX2 (Bruker, 2004); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The structure of the title compound, showing 50% probability displacement ellipsoids for the non-hydrogen atoms. The H atoms are depicted as circles of arbitrary radius. The unlabelled atoms of the imidazolium cation are related to the labelled ones by 3/2 - x, 3/2 - y, -z; for the anion, the symmetry operation for Br1 is 1 - x + 1, y, 1/2 - z.
[Figure 2] Fig. 2. A view of the crystal packing along the b axis. Hydrogen bonds are shown as dashed lines.
3,3'-Bis(3-methoxybenzyl)-1,1'-ethylenediimidazolium dibromide top
Crystal data top
C24H28N4O22+·2Br−F(000) = 572
Mr = 564.32Dx = 1.546 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 1952 reflections
a = 18.340 (6) Åθ = 3.3–26.3°
b = 5.3566 (17) ŵ = 3.37 mm−1
c = 12.340 (4) ÅT = 298 K
β = 91.491 (9)°Rod, white
V = 1211.9 (7) Å30.35 × 0.20 × 0.15 mm
Z = 2
Data collection top
Bruker SMART APEXII
diffractometer		2609 independent reflections
Radiation source: fine-focus sealed tube1838 reflections with I > 2σ
graphiteRint = 0.050
ω scansθmax = 27.0°, θmin = 3.3°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)		h = −14→23
Tmin = 0.366, Tmax = 0.600k = −6→6
6855 measured reflectionsl = −14→15
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.052Hydrogen site location: difference Fourier map
wR(F2) = 0.143H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.0825P)2 + 0.0975P]
where P = (Fo2 + 2Fc2)/3
2609 reflections(Δ/σ)max = 0.001
145 parametersΔρmax = 0.71 e Å−3
0 restraintsΔρmin = −1.24 e Å−3
Crystal data top
C24H28N4O22+·2Br−V = 1211.9 (7) Å3
Mr = 564.32Z = 2
Monoclinic, P21/cMo Kα radiation
a = 18.340 (6) ŵ = 3.37 mm−1
b = 5.3566 (17) ÅT = 298 K
c = 12.340 (4) Å0.35 × 0.20 × 0.15 mm
β = 91.491 (9)°
Data collection top
Bruker SMART APEXII
diffractometer		2609 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2003)		1838 reflections with I > 2σ
Tmin = 0.366, Tmax = 0.600Rint = 0.050
6855 measured reflectionsθmax = 27.0°
Refinement top
R[F2 > 2σ(F2)] = 0.052H-atom parameters constrained
wR(F2) = 0.143Δρmax = 0.71 e Å−3
S = 1.00Δρmin = −1.24 e Å−3
2609 reflectionsAbsolute structure: ?
145 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

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 (Å2) top
xyzUiso*/Ueq
N10.43660 (17)0.3916 (6)0.1046 (3)0.0292 (7)
N20.33797 (15)0.2134 (6)0.1563 (2)0.0272 (7)
O10.09061 (18)0.8336 (7)0.1978 (3)0.0551 (9)
Br10.34564 (2)0.59558 (9)0.39315 (4)0.0443 (2)
C10.3639 (2)0.4034 (7)0.1010 (3)0.0318 (9)
H1A0.33610.52520.06550.038*
C20.3950 (2)0.0735 (7)0.1966 (3)0.0305 (9)
H2A0.3917−0.07020.23850.037*
C30.4573 (2)0.1845 (8)0.1637 (3)0.0331 (9)
H3A0.50480.13090.17830.040*
C40.4858 (2)0.5616 (7)0.0499 (3)0.0301 (9)
H4A0.52620.60560.09840.036*
H4B0.46000.71360.02990.036*
C50.2612 (2)0.1516 (9)0.1779 (4)0.0478 (13)
H5A0.25380.15730.25540.057*
H5B0.2511−0.01730.15340.057*
C60.2085 (2)0.3286 (8)0.1218 (4)0.0353 (10)
C70.1942 (2)0.3068 (10)0.0106 (4)0.0504 (12)
H7A0.21720.1854−0.03000.060*
C80.1452 (3)0.4690 (11)−0.0375 (4)0.0549 (13)
H8A0.13600.4578−0.11190.066*
C90.1094 (2)0.6460 (9)0.0203 (4)0.0470 (12)
H9A0.07630.7530−0.01420.056*
C100.1230 (2)0.6648 (8)0.1315 (4)0.0375 (10)
C110.1735 (2)0.5067 (9)0.1817 (4)0.0361 (9)
H11A0.18350.52110.25570.043*
C120.0360 (3)0.9930 (12)0.1522 (5)0.0641 (15)
H12A0.01821.10190.20730.096*
H12B−0.00350.89400.12310.096*
H12C0.05641.09090.09530.096*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0268 (16)0.0313 (18)0.0295 (17)−0.0003 (13)0.0001 (13)0.0021 (14)
N20.0241 (16)0.0276 (18)0.0298 (17)0.0021 (13)−0.0011 (13)0.0040 (14)
O10.053 (2)0.053 (2)0.060 (2)0.0171 (16)−0.0040 (16)−0.0099 (17)
Br10.0467 (3)0.0480 (3)0.0380 (3)−0.0161 (2)−0.00102 (19)0.0012 (2)
C10.030 (2)0.030 (2)0.036 (2)0.0073 (16)−0.0012 (16)0.0039 (17)
C20.029 (2)0.030 (2)0.032 (2)−0.0002 (16)−0.0018 (16)0.0090 (17)
C30.029 (2)0.036 (2)0.034 (2)0.0047 (17)−0.0043 (16)0.0071 (18)
C40.031 (2)0.031 (2)0.028 (2)−0.0029 (16)−0.0002 (16)0.0006 (16)
C50.021 (2)0.051 (3)0.071 (3)−0.0005 (19)0.004 (2)0.024 (2)
C60.0225 (19)0.037 (2)0.047 (2)−0.0039 (17)−0.0012 (17)0.0074 (19)
C70.038 (3)0.059 (3)0.055 (3)0.008 (2)0.007 (2)−0.008 (3)
C80.054 (3)0.075 (4)0.036 (3)0.009 (3)−0.006 (2)−0.002 (2)
C90.036 (2)0.055 (3)0.049 (3)0.011 (2)−0.006 (2)0.010 (2)
C100.029 (2)0.037 (2)0.046 (3)−0.0011 (18)0.0003 (18)−0.0017 (19)
C110.028 (2)0.043 (2)0.038 (2)−0.0042 (19)−0.0045 (17)0.003 (2)
C120.052 (3)0.056 (3)0.084 (4)0.020 (3)0.003 (3)−0.006 (3)
Geometric parameters (Å, °) top
N1—C11.334 (5)C5—H5A0.9700
N1—C31.375 (5)C5—H5B0.9700
N1—C41.460 (5)C6—C111.376 (6)
N2—C11.321 (5)C6—C71.396 (6)
N2—C21.369 (5)C7—C81.374 (7)
N2—C51.477 (5)C7—H7A0.9300
O1—C101.366 (5)C8—C91.365 (7)
O1—C121.422 (6)C8—H8A0.9300
C1—H1A0.9300C9—C101.391 (6)
C2—C31.360 (6)C9—H9A0.9300
C2—H2A0.9300C10—C111.389 (6)
C3—H3A0.9300C11—H11A0.9300
C4—C4i1.502 (7)C12—H12A0.9600
C4—H4A0.9700C12—H12B0.9600
C4—H4B0.9700C12—H12C0.9600
C5—C61.509 (6)
C1—N1—C3108.6 (3)C6—C5—H5B109.2
C1—N1—C4125.7 (3)H5A—C5—H5B107.9
C3—N1—C4125.6 (3)C11—C6—C7120.5 (4)
C1—N2—C2109.1 (3)C11—C6—C5119.5 (4)
C1—N2—C5128.6 (3)C7—C6—C5120.0 (4)
C2—N2—C5122.3 (3)C8—C7—C6118.5 (5)
C10—O1—C12118.2 (4)C8—C7—H7A120.8
N2—C1—N1108.6 (3)C6—C7—H7A120.8
N2—C1—H1A125.7C9—C8—C7122.1 (5)
N1—C1—H1A125.7C9—C8—H8A119.0
C3—C2—N2107.0 (3)C7—C8—H8A119.0
C3—C2—H2A126.5C8—C9—C10119.4 (4)
N2—C2—H2A126.5C8—C9—H9A120.3
C2—C3—N1106.7 (3)C10—C9—H9A120.3
C2—C3—H3A126.6O1—C10—C11115.5 (4)
N1—C3—H3A126.6O1—C10—C9124.7 (4)
N1—C4—C4i109.6 (4)C11—C10—C9119.7 (4)
N1—C4—H4A109.7C6—C11—C10119.9 (4)
C4i—C4—H4A109.7C6—C11—H11A120.1
N1—C4—H4B109.7C10—C11—H11A120.1
C4i—C4—H4B109.7O1—C12—H12A109.5
H4A—C4—H4B108.2O1—C12—H12B109.5
N2—C5—C6112.3 (3)H12A—C12—H12B109.5
N2—C5—H5A109.2O1—C12—H12C109.5
C6—C5—H5A109.2H12A—C12—H12C109.5
N2—C5—H5B109.2H12B—C12—H12C109.5
Symmetry codes: (i) −x+1, −y+1, −z.
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···Br1ii0.932.773.657 (4)161
C3—H3A···Br1iii0.932.913.729 (4)148
C4—H4B···Br1iv0.972.853.669 (4)143
Symmetry codes: (ii) x, y−1, z; (iii) −x+1, y−1/2, −z+1/2; (iv) x, −y+3/2, z−1/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···Br1i0.932.773.657 (4)161
C3—H3A···Br1ii0.932.913.729 (4)148
C4—H4B···Br1iii0.972.853.669 (4)143
Symmetry codes: (i) x, y−1, z; (ii) −x+1, y−1/2, −z+1/2; (iii) x, −y+3/2, z−1/2.
Acknowledgements top

The authors thank the National Science Council of Taiwan for financial support of this work.

references
References top

Bruker (2004). APEX2. Bruker AXS Inc., Madison, Wisconsin, USA.

Cheng, P.-Y., Chen, C.-Y. & Lee, H. M. (2006). Acta Cryst. E62, o5850–o5851.

Hillier, A. C., Grasa, G. A., Viciu, M. S., Lee, H. M., Yang, C. & Nolan, S. P. (2002). J. Organomet. Chem. 653, 69–82.

Lee, H. M., Chen, C.-Y., Chen, W.-L. & Lin, H.-C. (2007). Acta Cryst. E63, o315–o316.

Lee, H. M. & Chiu, P.-L. (2004). Acta Cryst. E60, ol385-ol386.

Lee, H. M., Lu, C. Y., Chen, C. Y., Chen, W. L., Lin, H. C., Chiu, P. L. & Cheng, P. Y. (2004). Tetrahedron, 60, 5807–5825.

Sheldrick, G. M. (2003). SADABS. University of Göttingen, Germany.

Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122.