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

Lee, H.M.; Lu, C.-Y.

doi:10.1107/S1600536808031863

organic compounds

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ISSN: 2056-9890

Volume 64| Part 11| November 2008| Page o2086

doi:10.1107/S1600536808031863

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

Hon Man Lee ^a ^* and Chi-Ying Lu ^a

^aNational Changhua University of Education, Department of Chemistry, Changhua 50058, Taiwan
^*Correspondence e-mail: leehm@cc.ncue.edu.tw

(Received 30 September 2008; accepted 3 October 2008; online 9 October 2008)

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.

Related literature

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 , 2007 ). For a review of N-heterocyclic carbenes, see: Hillier et al. (2002 ).

Experimental

Crystal data

C₂₄H₂₈N₄O₂²⁺·2Br⁻
M_r = 564.32
Monoclinic, P 2₁ /c
a = 18.340 (6) Å
b = 5.3566 (17) Å
c = 12.340 (4) Å
β = 91.491 (9)°
V = 1211.9 (7) Å³
Z = 2
Mo Kα radiation
μ = 3.37 mm⁻¹
T = 298 (2) K
0.35 × 0.20 × 0.15 mm

Data collection

Bruker SMART APEXII diffractometer
Absorption correction: multi-scan (SADABS; Sheldrick, 2003 ) T_min = 0.366, T_max = 0.600
6855 measured reflections
2609 independent reflections
1838 reflections with I > 2σ
R_int = 0.050

Refinement

R[F² > 2σ(F²)] = 0.052
wR(F²) = 0.143
S = 1.00
2609 reflections
145 parameters
H-atom parameters constrained
Δρ_max = 0.71 e Å⁻³
Δρ_min = −1.24 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2A⋯Br1ⁱ	0.93	2.77	3.657 (4)	161
C3—H3A⋯Br1ⁱⁱ	0.93	2.91	3.729 (4)	148
C4—H4B⋯Br1ⁱⁱⁱ	0.97	2.85	3.669 (4)	143
Symmetry codes: (i) x, y-1, z; (ii) $[-x+1, y-{\script{1\over 2}}, -z+{\script{1\over 2}}]$ ; (iii) $[x, -y+{\script{3\over 2}}, z-{\script{1\over 2}}]$ .

Data collection: APEX2 (Bruker, 2004 ); cell refinement: APEX2; data reduction: SAINT (Bruker, 2004); 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.

Supporting information

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536808031863/wn2283sup1.cif

Structure factors: contains datablock I. DOI: 10.1107/S1600536808031863/wn2283Isup2.hkl

checkCIF report

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.

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

	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.
	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
M_r = 564.32	D_x = 1.546 Mg m⁻³
Monoclinic, P2₁/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 1952 reflections
a = 18.340 (6) Å	θ = 3.3–26.3°
b = 5.3566 (17) Å	µ = 3.37 mm⁻¹
c = 12.340 (4) Å	T = 298 K
β = 91.491 (9)°	Rod, white
V = 1211.9 (7) Å³	0.35 × 0.20 × 0.15 mm
Z = 2

Data collection top

Bruker SMART APEXII diffractometer	2609 independent reflections
Radiation source: fine-focus sealed tube	1838 reflections with I > 2σ
Graphite monochromator	R_int = 0.050
ω scans	θ_max = 27.0°, θ_min = 3.3°
Absorption correction: multi-scan (SADABS; Sheldrick, 2003)	h = −14→23
T_min = 0.366, T_max = 0.600	k = −6→6
6855 measured reflections	l = −14→15

Refinement top

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)] = 0.052	Hydrogen site location: difference Fourier map
wR(F²) = 0.143	H-atom parameters constrained
S = 1.00	w = 1/[σ²(F_o²) + (0.0825P)² + 0.0975P] where P = (F_o² + 2F_c²)/3
2609 reflections	(Δ/σ)_max = 0.001
145 parameters	Δρ_max = 0.71 e Å⁻³
0 restraints	Δρ_min = −1.24 e Å⁻³

Crystal data top

C₂₄H₂₈N₄O₂²⁺·2Br⁻	V = 1211.9 (7) Å³
M_r = 564.32	Z = 2
Monoclinic, P2₁/c	Mo Kα radiation
a = 18.340 (6) Å	µ = 3.37 mm⁻¹
b = 5.3566 (17) Å	T = 298 K
c = 12.340 (4) Å	0.35 × 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
T_min = 0.366, T_max = 0.600	R_int = 0.050
6855 measured reflections

Refinement top

R[F² > 2σ(F²)] = 0.052	0 restraints
wR(F²) = 0.143	H-atom parameters constrained
S = 1.00	Δρ_max = 0.71 e Å⁻³
2609 reflections	Δρ_min = −1.24 e Å⁻³
145 parameters

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

	x	y	z	U_iso*/U_eq
N1	0.43660 (17)	0.3916 (6)	0.1046 (3)	0.0292 (7)
N2	0.33797 (15)	0.2134 (6)	0.1563 (2)	0.0272 (7)
O1	0.09061 (18)	0.8336 (7)	0.1978 (3)	0.0551 (9)
Br1	0.34564 (2)	0.59558 (9)	0.39315 (4)	0.0443 (2)
C1	0.3639 (2)	0.4034 (7)	0.1010 (3)	0.0318 (9)
H1A	0.3361	0.5252	0.0655	0.038*
C2	0.3950 (2)	0.0735 (7)	0.1966 (3)	0.0305 (9)
H2A	0.3917	−0.0702	0.2385	0.037*
C3	0.4573 (2)	0.1845 (8)	0.1637 (3)	0.0331 (9)
H3A	0.5048	0.1309	0.1783	0.040*
C4	0.4858 (2)	0.5616 (7)	0.0499 (3)	0.0301 (9)
H4A	0.5262	0.6056	0.0984	0.036*
H4B	0.4600	0.7136	0.0299	0.036*
C5	0.2612 (2)	0.1516 (9)	0.1779 (4)	0.0478 (13)
H5A	0.2538	0.1573	0.2554	0.057*
H5B	0.2511	−0.0173	0.1534	0.057*
C6	0.2085 (2)	0.3286 (8)	0.1218 (4)	0.0353 (10)
C7	0.1942 (2)	0.3068 (10)	0.0106 (4)	0.0504 (12)
H7A	0.2172	0.1854	−0.0300	0.060*
C8	0.1452 (3)	0.4690 (11)	−0.0375 (4)	0.0549 (13)
H8A	0.1360	0.4578	−0.1119	0.066*
C9	0.1094 (2)	0.6460 (9)	0.0203 (4)	0.0470 (12)
H9A	0.0763	0.7530	−0.0142	0.056*
C10	0.1230 (2)	0.6648 (8)	0.1315 (4)	0.0375 (10)
C11	0.1735 (2)	0.5067 (9)	0.1817 (4)	0.0361 (9)
H11A	0.1835	0.5211	0.2557	0.043*
C12	0.0360 (3)	0.9930 (12)	0.1522 (5)	0.0641 (15)
H12A	0.0182	1.1019	0.2073	0.096*
H12B	−0.0035	0.8940	0.1231	0.096*
H12C	0.0564	1.0909	0.0953	0.096*

Atomic displacement parameters (Å²) top

	U¹¹	U²²	U³³	U¹²	U¹³	U²³
N1	0.0268 (16)	0.0313 (18)	0.0295 (17)	−0.0003 (13)	0.0001 (13)	0.0021 (14)
N2	0.0241 (16)	0.0276 (18)	0.0298 (17)	0.0021 (13)	−0.0011 (13)	0.0040 (14)
O1	0.053 (2)	0.053 (2)	0.060 (2)	0.0171 (16)	−0.0040 (16)	−0.0099 (17)
Br1	0.0467 (3)	0.0480 (3)	0.0380 (3)	−0.0161 (2)	−0.00102 (19)	0.0012 (2)
C1	0.030 (2)	0.030 (2)	0.036 (2)	0.0073 (16)	−0.0012 (16)	0.0039 (17)
C2	0.029 (2)	0.030 (2)	0.032 (2)	−0.0002 (16)	−0.0018 (16)	0.0090 (17)
C3	0.029 (2)	0.036 (2)	0.034 (2)	0.0047 (17)	−0.0043 (16)	0.0071 (18)
C4	0.031 (2)	0.031 (2)	0.028 (2)	−0.0029 (16)	−0.0002 (16)	0.0006 (16)
C5	0.021 (2)	0.051 (3)	0.071 (3)	−0.0005 (19)	0.004 (2)	0.024 (2)
C6	0.0225 (19)	0.037 (2)	0.047 (2)	−0.0039 (17)	−0.0012 (17)	0.0074 (19)
C7	0.038 (3)	0.059 (3)	0.055 (3)	0.008 (2)	0.007 (2)	−0.008 (3)
C8	0.054 (3)	0.075 (4)	0.036 (3)	0.009 (3)	−0.006 (2)	−0.002 (2)
C9	0.036 (2)	0.055 (3)	0.049 (3)	0.011 (2)	−0.006 (2)	0.010 (2)
C10	0.029 (2)	0.037 (2)	0.046 (3)	−0.0011 (18)	0.0003 (18)	−0.0017 (19)
C11	0.028 (2)	0.043 (2)	0.038 (2)	−0.0042 (19)	−0.0045 (17)	0.003 (2)
C12	0.052 (3)	0.056 (3)	0.084 (4)	0.020 (3)	0.003 (3)	−0.006 (3)

Geometric parameters (Å, º) top

N1—C1	1.334 (5)	C5—H5A	0.9700
N1—C3	1.375 (5)	C5—H5B	0.9700
N1—C4	1.460 (5)	C6—C11	1.376 (6)
N2—C1	1.321 (5)	C6—C7	1.396 (6)
N2—C2	1.369 (5)	C7—C8	1.374 (7)
N2—C5	1.477 (5)	C7—H7A	0.9300
O1—C10	1.366 (5)	C8—C9	1.365 (7)
O1—C12	1.422 (6)	C8—H8A	0.9300
C1—H1A	0.9300	C9—C10	1.391 (6)
C2—C3	1.360 (6)	C9—H9A	0.9300
C2—H2A	0.9300	C10—C11	1.389 (6)
C3—H3A	0.9300	C11—H11A	0.9300
C4—C4ⁱ	1.502 (7)	C12—H12A	0.9600
C4—H4A	0.9700	C12—H12B	0.9600
C4—H4B	0.9700	C12—H12C	0.9600
C5—C6	1.509 (6)

C1—N1—C3	108.6 (3)	C6—C5—H5B	109.2
C1—N1—C4	125.7 (3)	H5A—C5—H5B	107.9
C3—N1—C4	125.6 (3)	C11—C6—C7	120.5 (4)
C1—N2—C2	109.1 (3)	C11—C6—C5	119.5 (4)
C1—N2—C5	128.6 (3)	C7—C6—C5	120.0 (4)
C2—N2—C5	122.3 (3)	C8—C7—C6	118.5 (5)
C10—O1—C12	118.2 (4)	C8—C7—H7A	120.8
N2—C1—N1	108.6 (3)	C6—C7—H7A	120.8
N2—C1—H1A	125.7	C9—C8—C7	122.1 (5)
N1—C1—H1A	125.7	C9—C8—H8A	119.0
C3—C2—N2	107.0 (3)	C7—C8—H8A	119.0
C3—C2—H2A	126.5	C8—C9—C10	119.4 (4)
N2—C2—H2A	126.5	C8—C9—H9A	120.3
C2—C3—N1	106.7 (3)	C10—C9—H9A	120.3
C2—C3—H3A	126.6	O1—C10—C11	115.5 (4)
N1—C3—H3A	126.6	O1—C10—C9	124.7 (4)
N1—C4—C4ⁱ	109.6 (4)	C11—C10—C9	119.7 (4)
N1—C4—H4A	109.7	C6—C11—C10	119.9 (4)
C4ⁱ—C4—H4A	109.7	C6—C11—H11A	120.1
N1—C4—H4B	109.7	C10—C11—H11A	120.1
C4ⁱ—C4—H4B	109.7	O1—C12—H12A	109.5
H4A—C4—H4B	108.2	O1—C12—H12B	109.5
N2—C5—C6	112.3 (3)	H12A—C12—H12B	109.5
N2—C5—H5A	109.2	O1—C12—H12C	109.5
C6—C5—H5A	109.2	H12A—C12—H12C	109.5
N2—C5—H5B	109.2	H12B—C12—H12C	109.5

Symmetry code: (i) −x+1, −y+1, −z.

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···Br1ⁱⁱ	0.93	2.77	3.657 (4)	161
C3—H3A···Br1ⁱⁱⁱ	0.93	2.91	3.729 (4)	148
C4—H4B···Br1^iv	0.97	2.85	3.669 (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.

Experimental details

Crystal data
Chemical formula	C₂₄H₂₈N₄O₂²⁺·2Br⁻
M_r	564.32
Crystal system, space group	Monoclinic, P2₁/c
Temperature (K)	298
a, b, c (Å)	18.340 (6), 5.3566 (17), 12.340 (4)
β (°)	91.491 (9)
V (Å³)	1211.9 (7)
Z	2
Radiation type	Mo Kα
µ (mm⁻¹)	3.37
Crystal size (mm)	0.35 × 0.20 × 0.15

Data collection
Diffractometer	Bruker SMART APEXII diffractometer
Absorption correction	Multi-scan (SADABS; Sheldrick, 2003)
T_min, T_max	0.366, 0.600
No. of measured, independent and observed (I > 2σ) reflections	6855, 2609, 1838
R_int	0.050
(sin θ/λ)_max (Å⁻¹)	0.639

Refinement
R[F² > 2σ(F²)], wR(F²), S	0.052, 0.143, 1.00
No. of reflections	2609
No. of parameters	145
H-atom treatment	H-atom parameters constrained
Δρ_max, Δρ_min (e Å⁻³)	0.71, −1.24

Computer programs: APEX2 (Bruker, 2004), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top

D—H···A	D—H	H···A	D···A	D—H···A
C2—H2A···Br1ⁱ	0.93	2.77	3.657 (4)	160.9
C3—H3A···Br1ⁱⁱ	0.93	2.91	3.729 (4)	147.8
C4—H4B···Br1ⁱⁱⁱ	0.97	2.85	3.669 (4)	143.0

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

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

References

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