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Acta Cryst. (2009). E65, o637    [ doi:10.1107/S1600536809006710 ]

1,3-Bis[(6-methyl-2-pyridyl)methyl]imidazolium bromide

G. Y. Kim, S.-K. Park, D.-H. Lee and G. Park

Abstract top

The title compound, C17H19N4+·Br-, is built up from 1,3-bis[(6-methyl-2-pyridinyl)methyl]imidazolium cations and bromide anions. Each of two 6-methyl-2-pyridyl rings is rotated out of the imidazole plane, making dihedral angles of 79.90 (9) and 86.40 (9)°. The packing is consolidated by aromatic [pi]-[pi] interactions between the pyridine rings of neighbouring molecules [centroid-centroid distance = 3.554 (2) Å] and by weak C-H...N and C-H...Br hydrogen bonds.

Comment top

Many intensive researches have been focused on the synthesis of N-heterocyclic carbenes (NHCs) ligands due to their potential applications in important organic syntheses, such as Pd–catalysed Heck– and Suzuki–coupling, Co–catalysed ethylene copolymerisation, Ru–catalysed olefin metathesis and Rh–catalyse hydrosilylation (Frenzel et al., 1999; Enders et al., 1996; Gardiner et al., 1999; McGuinness et al., 1998; Weskamp et al., 1999a,b); Zhang & Trudell, 2000). We have interested in the use of tridentate N-heterocyclic carbene ligands. Here we report the crystal structure of the title compound, 1,3-bis[(6-methyl-2-pyridinyl)methyl]imidazolium bromide (Fig. 1).

The asymmetric unit of the title compound consists the C17H9N4 cation and Br anion. Each of two 6–methylpyridine rings is rotated out of the imidazole plane, with dihedral angle of N1/C2–C6 of 79.90 (9)° and N4/C12–C16 of 86.40 (9)°, respectively. The crystal packing (Fig. 2) is stabilized by intermolecular aromatic π—π interactions between the pyridine rings of neighbouring molecules. The Cg—Cgiii distance of 3.554 (2) Å (Cg is the centroid of the N1/C2-C6 pyridine ring; symmetry code as in Fig. 2). The molecular packing is further stabilized by C—H···N interactions between the hydrogen of 7–methylene group and the N atom of pyridine ring of the neighbouring molecule, with a C7—H7A···N4i separation of 2.34 (1) Å (Table 1 and Fig. 2; symmetry code as in Fig. 2). Additionally, five different intermolecular C—H···Br hydrogen bonds in the structure are observed (Table 1 & Fig. 2).

Related literature top

For the synthesis of N-heterocyclic carbenes, see: Arduengo et al. (1991); Öfele (1968); Wanzlick & Schonherr (1968). For related structures, see: Weskamp et al. (1999a,b).

For related literature, see: Enders et al. (1996); Frenzel et al. (1999); Gardiner et al. (1999); Herrmann et al. (1998); McGuinness et al. (1998); Wanzlick & Schönherr (1968); Zhang & Trudell (2000).

Experimental top

Synthesis of H(MepyCH2)Im (1a): A mixture of imidazole (0.36 g, 6.0 mmol), 2-bromomethyl-6-methylpyridine (1.11 g, 6.0 mmol) and triethylamine (1.82 g, 1.8 mmol) in toluene (50 mL) was refluxed at 383 K for 10 h. After cooling, saturated aqueous NaHCO3 solution was added and extracted with CH2Cl2 (3 x 20 mL). The combined organic fractions were dried over Na2SO4, filtered, and concentrated under reduced pressure to afford a dark colored solid in 53.0 % yield. Spectroscopic analysis: 1H NMR(CDCl3, 400MHz) : δ 7.62 (s, 1H, CH), 7.54 (t, 1H, J = 10 Hz, CH), 7.12 (s, 1H, CH), 7.09 (d, 1H, J = 1 Hz, CH), 6.99 (s, 1H, CH), 6.70 (d, 1H, J = 0.6Hz, CH), 5.21(s, 2H, CH2), 2.56 (s, 3H, CH3). 13C NMR (CDCl3, 100MHz): δ 157.8, 154.1, 137.5, 136.6, 123.2, 122.5, 121.4, 118.9, 52.3, 23.9.

Synthesis of [H(MepyCH2)2-Im]Br (1): A mixture of (1a), H(MepyCH2)Im, (0.52 g, 3.0 mmol) and 2-bromomethyl-6-methylpyridine (0.56 g, 3.0 mmol) in toluene (50 mL) was refluxed at 383 K for 14 h. After cooling, the solvents were removed by high-vacuum rotary evaporation. The residue was washed with Et2O (5 x100 mL), and dried under the reduced pressure to afford a brown solid in 89.0 % yield. Single crystlas suitable for X-ray crystallography were obtained by Et2O diffusion into a MeOH solution of the compound. Spectroscopic analysis: 1H NMR (CDCl3, 400 MHz) : δ 10.52 (s, 1H, CH), 7.66 (s, 2H, CH), 7.62 (t, 2H, J = 7.8 Hz), 7.54 (d, 2H, J = 7 Hz, CH), 7.14 (d, 2H, J = 7 Hz, CH), 5.65 (s, 4H, CH2), 2.50 (s, 6H, CH3). 13C NMR (CDCl3, 100 MHz): δ 158.8, 151.3, 137.9, 137.3, 123.7, 122.1, 121.0, 54.2, 24.4.

Refinement top

All H atoms were geometrically positioned and refined using a riding model, with C—H = 0.95 Å for the aryl, 0.99 Å for the methylene, and 0.00 Å for the methyl H atoms, respectively, and with Uiso(H) = 1.2Ueq(C) for the aryl and methylene H atoms, and 1.5Ueq(C) for the methyl H atoms.

Computing details top

Data collection: SMART (Bruker, 1997); cell refinement: SMART (Bruker, 1997); data reduction: SAINT (Bruker, 1997); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound, showing displacement ellipsoids drawn at the 50% probability level.
[Figure 2] Fig. 2. π—π, C—H···N and C—H···Br interactions (dotted lines) in the title compound. Cg denotes the ring centroids. [Symmetry code : (i) -x+1, y+1/2, -z+3/2; (ii) -x, y+1/2, -z+3/2; (iii) -x+1, -y, -z+1; (iv) -x+1, y-1/2, -z+3/2.]
1,3-Bis[(6-methyl-2-pyridyl)methyl]imidazolium bromide top
Crystal data top
C17H19N4+·Br−F(000) = 736
Mr = 359.27Dx = 1.430 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 3923 reflections
a = 8.2951 (4) Åθ = 2.1–28.3°
b = 12.4992 (5) ŵ = 2.47 mm−1
c = 16.1786 (7) ÅT = 173 K
β = 95.709 (1)°Block, yellow
V = 1669.11 (13) Å30.40 × 0.25 × 0.15 mm
Z = 4
Data collection top
Bruker SMART CCD area-detector
diffractometer		3923 independent reflections
Radiation source: fine-focus sealed tube2861 reflections with I > 2σ(I)
graphiteRint = 0.070
Detector resolution: 10.0 pixels mm-1θmax = 28.3°, θmin = 2.1°
φ and ω scansh = −10→9
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		k = −8→16
Tmin = 0.439, Tmax = 0.709l = −21→20
10482 measured reflections
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)] = 0.037Hydrogen site location: difference Fourier map
wR(F2) = 0.094H-atom parameters constrained
S = 1.00 w = 1/[σ2(Fo2) + (0.0442P)2]
where P = (Fo2 + 2Fc2)/3
3923 reflections(Δ/σ)max < 0.001
201 parametersΔρmax = 0.92 e Å−3
0 restraintsΔρmin = −0.49 e Å−3
Crystal data top
C17H19N4+·Br−V = 1669.11 (13) Å3
Mr = 359.27Z = 4
Monoclinic, P21/cMo Kα radiation
a = 8.2951 (4) ŵ = 2.47 mm−1
b = 12.4992 (5) ÅT = 173 K
c = 16.1786 (7) Å0.40 × 0.25 × 0.15 mm
β = 95.709 (1)°
Data collection top
Bruker SMART CCD area-detector
diffractometer		3923 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 1996)		2861 reflections with I > 2σ(I)
Tmin = 0.439, Tmax = 0.709Rint = 0.070
10482 measured reflectionsθmax = 28.3°
Refinement top
R[F2 > 2σ(F2)] = 0.037H-atom parameters constrained
wR(F2) = 0.094Δρmax = 0.92 e Å−3
S = 1.00Δρmin = −0.49 e Å−3
3923 reflectionsAbsolute structure: ?
201 parametersFlack parameter: ?
0 restraintsRogers parameter: ?
Special details top

Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds 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 > 2sigma(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
Br0.25933 (3)−0.13979 (2)0.728857 (17)0.02867 (10)
N10.2300 (3)0.43039 (18)0.55743 (13)0.0278 (5)
N20.1795 (3)0.32251 (18)0.69967 (13)0.0249 (5)
N30.3401 (3)0.18620 (18)0.70972 (12)0.0251 (5)
N40.6655 (3)0.02641 (18)0.63640 (13)0.0278 (5)
C10.3308 (4)0.4122 (3)0.42228 (19)0.0461 (8)
H1A0.44470.39650.44010.069*
H1B0.32310.45110.36950.069*
H1C0.26990.34510.41510.069*
C20.2610 (3)0.4796 (2)0.48712 (16)0.0316 (6)
C30.2275 (4)0.5877 (2)0.47302 (19)0.0372 (7)
H3A0.24930.62050.42230.045*
C40.1625 (4)0.6461 (2)0.5333 (2)0.0405 (7)
H4A0.13890.71990.52490.049*
C50.1314 (3)0.5967 (2)0.60658 (19)0.0343 (7)
H5A0.08810.63580.64960.041*
C60.1653 (3)0.4883 (2)0.61548 (16)0.0268 (6)
C70.1255 (3)0.4340 (2)0.69380 (17)0.0283 (6)
H7A0.17700.47400.74220.034*
H7B0.00680.43630.69630.034*
C80.0851 (3)0.2329 (2)0.68219 (17)0.0297 (6)
H8A−0.02890.23160.66840.036*
C90.1843 (3)0.1478 (2)0.68830 (17)0.0302 (6)
H9A0.15380.07500.67960.036*
C100.3325 (3)0.2922 (2)0.71530 (15)0.0257 (6)
H10A0.42220.33860.72830.031*
C110.4884 (3)0.1223 (2)0.71751 (17)0.0280 (6)
H11A0.46510.05150.74110.034*
H11B0.57040.15820.75670.034*
C120.5575 (3)0.1063 (2)0.63500 (16)0.0251 (6)
C130.5148 (3)0.1686 (2)0.56543 (16)0.0298 (6)
H13A0.43820.22500.56670.036*
C140.5875 (3)0.1459 (2)0.49366 (18)0.0330 (6)
H14A0.56080.18650.44460.040*
C150.6987 (3)0.0642 (2)0.49443 (17)0.0331 (7)
H15A0.75000.04800.44600.040*
C160.7350 (3)0.0057 (2)0.56687 (17)0.0305 (6)
C170.8531 (4)−0.0873 (3)0.5706 (2)0.0445 (8)
H17A0.9412−0.07440.61440.067*
H17B0.8980−0.09430.51700.067*
H17C0.7964−0.15350.58260.067*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
Br0.02798 (15)0.02717 (15)0.03144 (16)0.00081 (11)0.00575 (11)0.00151 (12)
N10.0321 (12)0.0264 (12)0.0249 (11)−0.0012 (10)0.0022 (10)−0.0001 (9)
N20.0292 (12)0.0238 (11)0.0223 (11)−0.0008 (9)0.0057 (9)−0.0003 (9)
N30.0275 (12)0.0278 (12)0.0205 (11)0.0002 (10)0.0043 (9)0.0004 (9)
N40.0261 (12)0.0312 (13)0.0260 (11)−0.0004 (10)0.0014 (9)−0.0010 (10)
C10.063 (2)0.051 (2)0.0266 (15)0.0014 (17)0.0125 (15)0.0030 (14)
C20.0321 (15)0.0388 (16)0.0234 (13)−0.0044 (13)−0.0005 (11)0.0019 (12)
C30.0381 (17)0.0395 (18)0.0332 (16)−0.0073 (14)−0.0008 (13)0.0111 (14)
C40.0411 (17)0.0278 (16)0.052 (2)0.0000 (13)0.0002 (15)0.0080 (14)
C50.0347 (16)0.0268 (15)0.0415 (17)−0.0018 (13)0.0035 (13)−0.0015 (13)
C60.0234 (13)0.0292 (15)0.0273 (13)−0.0039 (11)−0.0008 (11)−0.0005 (11)
C70.0329 (15)0.0234 (14)0.0290 (14)0.0036 (11)0.0057 (12)−0.0016 (11)
C80.0279 (14)0.0296 (15)0.0318 (15)−0.0043 (12)0.0039 (12)−0.0017 (12)
C90.0315 (14)0.0280 (15)0.0315 (14)−0.0038 (12)0.0052 (12)−0.0033 (12)
C100.0315 (14)0.0246 (14)0.0211 (13)−0.0041 (11)0.0035 (11)−0.0027 (10)
C110.0304 (14)0.0296 (15)0.0241 (13)0.0062 (11)0.0034 (11)0.0028 (11)
C120.0241 (13)0.0259 (13)0.0251 (13)−0.0039 (11)0.0021 (11)−0.0023 (11)
C130.0367 (16)0.0260 (14)0.0271 (14)0.0015 (12)0.0045 (12)0.0020 (11)
C140.0381 (16)0.0355 (16)0.0258 (14)−0.0051 (13)0.0048 (12)0.0055 (12)
C150.0308 (15)0.0418 (17)0.0283 (14)−0.0083 (13)0.0116 (12)−0.0060 (13)
C160.0252 (14)0.0361 (16)0.0303 (14)−0.0014 (12)0.0023 (11)−0.0053 (12)
C170.0432 (18)0.053 (2)0.0372 (17)0.0125 (16)0.0055 (14)−0.0081 (15)
Geometric parameters (Å, °) top
N1—C61.339 (3)C6—C71.503 (4)
N1—C21.341 (3)C7—H7A0.9900
N2—C101.324 (3)C7—H7B0.9900
N2—C81.380 (3)C8—C91.343 (4)
N2—C71.464 (3)C8—H8A0.9500
N3—C101.330 (3)C9—H9A0.9500
N3—C91.389 (3)C10—H10A0.9500
N3—C111.462 (3)C11—C121.518 (4)
N4—C161.339 (3)C11—H11A0.9900
N4—C121.341 (3)C11—H11B0.9900
C1—C21.506 (4)C12—C131.385 (4)
C1—H1A0.9800C13—C141.390 (4)
C1—H1B0.9800C13—H13A0.9500
C1—H1C0.9800C14—C151.375 (4)
C2—C31.393 (4)C14—H14A0.9500
C3—C41.371 (5)C15—C161.389 (4)
C3—H3A0.9500C15—H15A0.9500
C4—C51.383 (4)C16—C171.518 (4)
C4—H4A0.9500C17—H17A0.9800
C5—C61.388 (4)C17—H17B0.9800
C5—H5A0.9500C17—H17C0.9800
C6—N1—C2118.1 (2)C9—C8—H8A126.4
C10—N2—C8108.7 (2)N2—C8—H8A126.4
C10—N2—C7124.5 (2)C8—C9—N3107.0 (2)
C8—N2—C7126.5 (2)C8—C9—H9A126.5
C10—N3—C9108.2 (2)N3—C9—H9A126.5
C10—N3—C11125.7 (2)N2—C10—N3108.8 (2)
C9—N3—C11125.9 (2)N2—C10—H10A125.6
C16—N4—C12118.2 (2)N3—C10—H10A125.6
C2—C1—H1A109.5N3—C11—C12112.6 (2)
C2—C1—H1B109.5N3—C11—H11A109.1
H1A—C1—H1B109.5C12—C11—H11A109.1
C2—C1—H1C109.5N3—C11—H11B109.1
H1A—C1—H1C109.5C12—C11—H11B109.1
H1B—C1—H1C109.5H11A—C11—H11B107.8
N1—C2—C3122.1 (3)N4—C12—C13123.3 (2)
N1—C2—C1117.0 (3)N4—C12—C11113.2 (2)
C3—C2—C1120.9 (3)C13—C12—C11123.5 (2)
C4—C3—C2119.1 (3)C12—C13—C14117.8 (3)
C4—C3—H3A120.5C12—C13—H13A121.1
C2—C3—H3A120.5C14—C13—H13A121.1
C3—C4—C5119.5 (3)C15—C14—C13119.4 (3)
C3—C4—H4A120.3C15—C14—H14A120.3
C5—C4—H4A120.3C13—C14—H14A120.3
C4—C5—C6118.1 (3)C14—C15—C16119.2 (3)
C4—C5—H5A120.9C14—C15—H15A120.4
C6—C5—H5A120.9C16—C15—H15A120.4
N1—C6—C5123.1 (3)N4—C16—C15122.1 (3)
N1—C6—C7118.9 (2)N4—C16—C17116.4 (3)
C5—C6—C7118.0 (2)C15—C16—C17121.4 (3)
N2—C7—C6113.2 (2)C16—C17—H17A109.5
N2—C7—H7A108.9C16—C17—H17B109.5
C6—C7—H7A108.9H17A—C17—H17B109.5
N2—C7—H7B108.9C16—C17—H17C109.5
C6—C7—H7B108.9H17A—C17—H17C109.5
H7A—C7—H7B107.8H17B—C17—H17C109.5
C9—C8—N2107.3 (2)
C6—N1—C2—C3−0.3 (4)C8—N2—C10—N3−0.9 (3)
C6—N1—C2—C1−178.9 (3)C7—N2—C10—N3−175.1 (2)
N1—C2—C3—C40.8 (4)C9—N3—C10—N20.9 (3)
C1—C2—C3—C4179.4 (3)C11—N3—C10—N2175.9 (2)
C2—C3—C4—C5−0.1 (4)C10—N3—C11—C12−89.3 (3)
C3—C4—C5—C6−1.1 (4)C9—N3—C11—C1284.9 (3)
C2—N1—C6—C5−1.0 (4)C16—N4—C12—C13−0.2 (4)
C2—N1—C6—C7178.4 (2)C16—N4—C12—C11−179.6 (2)
C4—C5—C6—N11.7 (4)N3—C11—C12—N4−163.2 (2)
C4—C5—C6—C7−177.7 (3)N3—C11—C12—C1317.3 (4)
C10—N2—C7—C673.2 (3)N4—C12—C13—C140.4 (4)
C8—N2—C7—C6−100.0 (3)C11—C12—C13—C14179.8 (3)
N1—C6—C7—N25.8 (3)C12—C13—C14—C15−0.5 (4)
C5—C6—C7—N2−174.8 (2)C13—C14—C15—C160.4 (4)
C10—N2—C8—C90.5 (3)C12—N4—C16—C150.1 (4)
C7—N2—C8—C9174.6 (2)C12—N4—C16—C17−178.4 (2)
N2—C8—C9—N30.1 (3)C14—C15—C16—N4−0.2 (4)
C10—N3—C9—C8−0.6 (3)C14—C15—C16—C17178.2 (3)
C11—N3—C9—C8−175.6 (2)
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C7—H7A···N4i0.992.343.308 (4)165
C7—H7B···Brii0.992.793.660 (3)147
C9—H9A···Br0.952.913.695 (3)141
C10—H10A···Bri0.952.683.521 (3)148
C11—H11A···Br0.992.933.801 (3)147
C11—H11B···Bri0.992.893.690 (3)138
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x, y+1/2, −z+3/2.
Table 1
Hydrogen-bond geometry (Å, °) top
D—H···AD—HH···AD···AD—H···A
C7—H7A···N4i0.992.343.308 (4)165
C7—H7B···Brii0.992.793.660 (3)147
C9—H9A···Br0.952.913.695 (3)141
C10—H10A···Bri0.952.683.521 (3)148
C11—H11A···Br0.992.933.801 (3)147
C11—H11B···Bri0.992.893.690 (3)138
Symmetry codes: (i) −x+1, y+1/2, −z+3/2; (ii) −x, y+1/2, −z+3/2.
Acknowledgements top

No acknowledgements.

references
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