3-(2-Bromo­benz­yl)-1-methyl-1H-imidazol-3-ium bromide

In the title compound, C₁₁H₁₂BrN₂⁺·Br⁻, the imidazole and phenyl rings are nearly perpendicular, making a dihedral angle of 87.71 (7)°. The crystal structure is stabilized by non-classical inter­molecular C—H⋯Br hydrogen bonds and inversion-related mol­ecules are linked through π–π inter­actions between the imidazole ring systems [centroid–centroid distance = 3.472 (6) Å].

Related literature

Imidazolium salts are used to obtain transition metal complexes of N-heterocyclic carbenes, which have become an important class of catalysts in organometallic chemistry and organic synthesis, see: Marion & Nolan (2008); Herrmann (2002); Qin et al. (2006). For related structures, Guo et al. (2008); Liu et al. (2003).

Experimental

Crystal data

• C₁₁H₁₂BrN₂⁺·Br⁻

• M_r = 332.05

• Orthorhombic, P b c a

• a = 8.4548 (10) Å

• b = 13.9166 (13) Å

• c = 20.831 (2) Å

• V = 2451.1 (5) ų

• Z = 8

• Mo Kα radiation

• μ = 6.58 mm⁻¹

• T = 298 K

• 0.42 × 0.40 × 0.21 mm

Data collection

• Bruker SMART 1K CCD area-detector diffractometer

• Absorption correction: multi-scan (SADABS; Sheldrick, 1996) T_min = 0.169, T_max = 0.339

• 9279 measured reflections

• 2158 independent reflections

• 1530 reflections with I > 2σ(I)

• R_int = 0.126

Refinement

• R[F² > 2σ(F²)] = 0.064

• wR(F²) = 0.130

• S = 1.19

• 2158 reflections

• 138 parameters

• H-atom parameters constrained

• Δρ_max = 0.74 e Å⁻³

• Δρ_min = −0.65 e Å⁻³

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C4—H4A⋯Br2^i	0.97	2.86	3.662 (6)	141
Symmetry code: (i) x+1, y, z.

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); 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.

Supporting information

S1. Comment

Imidazolium salts or its derivatives are used as ionic liquids, and in many organic transformations. They are used to obtain transition metal complexes of N-heterocyclic carbenes which have become a very important class of catalysts in organometallic chemistry and organic synthesis (Herrmann, 2002, Marion & Nolan, 2008). We here report the crystal structure of the title compound.

Bond lengths and angles in the title molecule (Fig. 1) are within normal ranges. The imidazole and the phenyl ring are nearly perpendicular, with a dihedral angle of 87.71 (2)°.

The molecular structure is stabilized by C—H···Br hydrogen bonds (Table 1). The crystal structure is stabilized by π-π interactions between the imidazole ring systems of the inversion related molecules, with a Cg1···Cg1ⁱ distance of 3.472 (6) Å [symmetry code: (i) 1-x, -y, 1-z].

Related literature

Imidazolium salts are used to obtain transition metal complexes of N-heterocyclic carbenes, which have become an important class of catalysts in organometallic chemistry and organic synthesis, see: Marion & Nolan (2008); Herrmann et al. (2002); Qin et al. (2006). For related structures, Guo et al. (2008); Liu et al. (2003).

S2. Experimental

1-methyl-1H-imidazole (0.615 g, 7.5 mmol) and 1-bromo-2-(bromomethyl)benzene (1.25 g, 5 mmol) in 20 ml of dioxane were refluxed for 12 h. After cooling the solution to room temperature, the mixture was filtered and afforded a colorless solid. Colourless single crystals suitable for X-ray diffraction were obtained by recrystallization from acetonitrile and diethyl ether.

S3. Refinement

H atoms were placed in calculated positions with C—H = 0.95–0.99 Å, and refined in riding mode with U_iso(H) = 1.2–1.5U_eq(C).

Computing details

Data collection: SMART (Bruker, 2007); cell refinement: SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); 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

Fig. 1. The molecular structure of the title compound, showing 30% probability displacement ellipsoids.

3-(2-Bromobenzyl)-1-methyl-1H-imidazol-3-ium bromide

Crystal data

C11H12BrN2^+·Br^−	Dx = 1.800 Mg m^−3
Mr = 332.05	Mo Kα radiation, λ = 0.71073 Å
Orthorhombic, Pbca	Cell parameters from 992 reflections
a = 8.4548 (10) Å	θ = 2.6–25.2°
b = 13.9166 (13) Å	µ = 6.58 mm^−1
c = 20.831 (2) Å	T = 298 K
V = 2451.1 (5) Å^3	Block, colourless
Z = 8	0.42 × 0.40 × 0.21 mm
F(000) = 1296

Data collection

Bruker SMART 1K CCD area-detector diffractometer	2158 independent reflections
Radiation source: fine-focus sealed tube	1530 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.126
ϕ and ω scans	θmax = 25.0°, θmin = 2.0°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)	h = −10→9
Tmin = 0.169, Tmax = 0.339	k = −15→16
9279 measured reflections	l = −15→24

Refinement

Refinement on F^2	Secondary atom site location: difference Fourier map
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.064	H-atom parameters constrained
wR(F^2) = 0.130	w = 1/[σ^2(Fo^2) + (0.0439P)^2 + 1.6882P] where P = (Fo^2 + 2Fc^2)/3
S = 1.19	(Δ/σ)max < 0.001
2158 reflections	Δρmax = 0.74 e Å^−3
138 parameters	Δρmin = −0.65 e Å^−3
0 restraints	Extinction correction: SHELXTL (Sheldrick, 2008), Fc^*=kFc[1+0.001xFc^2λ^3/sin(2θ)]^-1/4
Primary atom site location: structure-invariant direct methods	Extinction coefficient: 0.0051 (4)

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
Br1	0.76580 (9)	0.05373 (6)	0.26368 (5)	0.0618 (4)
Br2	0.09361 (7)	0.16571 (5)	0.46240 (4)	0.0464 (3)
N1	0.6110 (5)	0.0692 (4)	0.4078 (3)	0.0320 (14)
N2	0.4228 (6)	−0.0365 (4)	0.4189 (3)	0.0346 (14)
C1	0.4546 (7)	0.0545 (5)	0.4031 (3)	0.0329 (17)
H1	0.3803	0.1002	0.3908	0.039*
C2	0.5601 (8)	−0.0806 (5)	0.4353 (4)	0.0444 (19)
H2	0.5716	−0.1438	0.4490	0.053*
C3	0.6759 (8)	−0.0158 (5)	0.4282 (4)	0.0434 (19)
H3	0.7827	−0.0267	0.4359	0.052*
C4	0.6935 (7)	0.1600 (5)	0.3952 (4)	0.0393 (19)
H4A	0.8059	0.1473	0.3913	0.047*
H4B	0.6785	0.2026	0.4315	0.047*
C5	0.6377 (6)	0.2087 (5)	0.3363 (4)	0.0337 (18)
C6	0.6590 (7)	0.1733 (5)	0.2750 (4)	0.041 (2)
C7	0.6039 (9)	0.2206 (8)	0.2210 (4)	0.061 (2)
H7	0.6185	0.1945	0.1803	0.073*
C8	0.5265 (10)	0.3076 (8)	0.2288 (6)	0.069 (3)
H8	0.4887	0.3404	0.1930	0.083*
C9	0.5056 (9)	0.3454 (7)	0.2885 (6)	0.068 (3)
H9	0.4543	0.4040	0.2933	0.082*
C10	0.5604 (8)	0.2968 (5)	0.3419 (4)	0.049 (2)
H10	0.5454	0.3233	0.3824	0.059*
C11	0.2652 (7)	−0.0794 (6)	0.4187 (4)	0.056 (2)
H11A	0.1878	−0.0308	0.4279	0.084*
H11B	0.2599	−0.1288	0.4508	0.084*
H11C	0.2442	−0.1068	0.3773	0.084*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Br1	0.0619 (5)	0.0619 (6)	0.0615 (8)	−0.0090 (4)	0.0169 (4)	−0.0205 (5)
Br2	0.0390 (4)	0.0502 (5)	0.0500 (7)	0.0086 (3)	−0.0099 (3)	0.0048 (4)
N1	0.030 (3)	0.041 (3)	0.025 (4)	0.007 (3)	−0.002 (2)	0.000 (3)
N2	0.041 (3)	0.035 (3)	0.029 (4)	−0.001 (3)	0.002 (3)	0.000 (3)
C1	0.031 (3)	0.045 (4)	0.023 (5)	0.006 (3)	−0.005 (3)	0.002 (3)
C2	0.049 (4)	0.042 (4)	0.043 (6)	0.010 (4)	0.003 (3)	0.002 (4)
C3	0.041 (4)	0.056 (5)	0.034 (5)	0.020 (4)	−0.003 (3)	0.003 (4)
C4	0.034 (3)	0.045 (4)	0.039 (6)	−0.005 (3)	−0.005 (3)	−0.003 (4)
C5	0.025 (3)	0.039 (4)	0.037 (6)	−0.011 (3)	−0.002 (3)	0.004 (4)
C6	0.032 (3)	0.044 (4)	0.048 (6)	−0.019 (3)	0.004 (3)	−0.002 (4)
C7	0.055 (5)	0.094 (7)	0.033 (6)	−0.031 (5)	0.003 (4)	0.013 (5)
C8	0.051 (5)	0.087 (8)	0.069 (9)	−0.010 (5)	−0.003 (5)	0.045 (6)
C9	0.057 (5)	0.066 (6)	0.081 (9)	0.003 (4)	0.010 (5)	0.030 (6)
C10	0.045 (4)	0.051 (5)	0.052 (7)	−0.005 (3)	0.000 (4)	0.005 (4)
C11	0.045 (4)	0.062 (5)	0.060 (7)	−0.015 (4)	0.001 (4)	−0.005 (5)

Geometric parameters (Å, º)

Br1—C6	1.908 (7)	C5—C6	1.380 (10)
N1—C1	1.342 (7)	C5—C10	1.393 (9)
N1—C3	1.372 (8)	C6—C7	1.385 (11)
N1—C4	1.466 (8)	C7—C8	1.386 (13)
N2—C1	1.336 (9)	C7—H7	0.9300
N2—C2	1.357 (8)	C8—C9	1.362 (14)
N2—C11	1.460 (8)	C8—H8	0.9300
C1—H1	0.9300	C9—C10	1.382 (12)
C2—C3	1.338 (10)	C9—H9	0.9300
C2—H2	0.9300	C10—H10	0.9300
C3—H3	0.9300	C11—H11A	0.9600
C4—C5	1.480 (10)	C11—H11B	0.9600
C4—H4A	0.9700	C11—H11C	0.9600
C4—H4B	0.9700
C1—N1—C3	106.5 (6)	C10—C5—C4	118.9 (7)
C1—N1—C4	126.0 (5)	C5—C6—C7	122.6 (8)
C3—N1—C4	127.5 (5)	C5—C6—Br1	119.2 (6)
C1—N2—C2	108.6 (5)	C7—C6—Br1	118.2 (7)
C1—N2—C11	124.8 (6)	C6—C7—C8	118.6 (9)
C2—N2—C11	126.6 (6)	C6—C7—H7	120.7
N2—C1—N1	109.0 (5)	C8—C7—H7	120.7
N2—C1—H1	125.5	C9—C8—C7	120.4 (9)
N1—C1—H1	125.5	C9—C8—H8	119.8
C3—C2—N2	107.1 (6)	C7—C8—H8	119.8
C3—C2—H2	126.5	C8—C9—C10	120.2 (9)
N2—C2—H2	126.5	C8—C9—H9	119.9
C2—C3—N1	108.8 (6)	C10—C9—H9	119.9
C2—C3—H3	125.6	C9—C10—C5	121.3 (9)
N1—C3—H3	125.6	C9—C10—H10	119.3
N1—C4—C5	113.1 (5)	C5—C10—H10	119.3
N1—C4—H4A	109.0	N2—C11—H11A	109.5
C5—C4—H4A	109.0	N2—C11—H11B	109.5
N1—C4—H4B	109.0	H11A—C11—H11B	109.5
C5—C4—H4B	109.0	N2—C11—H11C	109.5
H4A—C4—H4B	107.8	H11A—C11—H11C	109.5
C6—C5—C10	116.9 (7)	H11B—C11—H11C	109.5
C6—C5—C4	124.2 (7)
C2—N2—C1—N1	1.3 (8)	N1—C4—C5—C10	114.2 (7)
C11—N2—C1—N1	−179.2 (7)	C10—C5—C6—C7	−1.5 (9)
C3—N1—C1—N2	−0.9 (8)	C4—C5—C6—C7	179.4 (6)
C4—N1—C1—N2	−179.3 (6)	C10—C5—C6—Br1	179.4 (4)
C1—N2—C2—C3	−1.1 (8)	C4—C5—C6—Br1	0.3 (8)
C11—N2—C2—C3	179.4 (7)	C5—C6—C7—C8	1.0 (10)
N2—C2—C3—N1	0.5 (9)	Br1—C6—C7—C8	−179.8 (5)
C1—N1—C3—C2	0.3 (8)	C6—C7—C8—C9	0.0 (11)
C4—N1—C3—C2	178.6 (7)	C7—C8—C9—C10	−0.5 (12)
C1—N1—C4—C5	−44.1 (9)	C8—C9—C10—C5	0.0 (11)
C3—N1—C4—C5	137.9 (7)	C6—C5—C10—C9	1.0 (10)
N1—C4—C5—C6	−66.7 (8)	C4—C5—C10—C9	−179.9 (6)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C4—H4A···Br2^i	0.97	2.86	3.662 (6)	141

Symmetry code: (i) x+1, y, z.