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Acta Cryst. (2010). E66, o2036    [ doi:10.1107/S1600536810027431 ]

1-Ethyl-3-(2,4,6-trimethylphenyl)imidazolium tetrafluoroborate

J.-T. Guan, J.-G. Hou, Z.-Y. Zhang and S.-Y. Zhao

Abstract top

The title compound, C14H19N2+·BF4-, was obtained by reaction of 1-ethyl-3-(2,4,6-trimethylphenyl)imidazolium tetrafluoroborate with sodium tetrafluoroborate. The imidazole ring makes a dihedral angle of 78.92 (13)° with the benzene ring.

Comment top

N-Heterocyclic carbenes (NHCs) have been playing an important role as ligands in organometallic chemistry and in catalysis ever since their isolation in the free state by Arduengo and coworkers in 1991 (Arduengo et al.,1991 and Arduengo et al., 1999). As part of our research,we designed and synthesized an unsymmetrical carbene precursor imidazolinium salt, namely the title complex (I). The molecular structure of the title complex consists of disubstituted imidazolium cation and tetrafluoroborate anion(Fig. 1). The imidazole ring and benzene ring are oriented at 78.92 (13)°, the imidazole and the plane of the atoms of N2 C13 C14 are oriented at 63.8 (2)°, the imidazole ring slightly deviates from planarity as indicated by the torsion angles: N1—C10—C11—N2 = 1.0 (3)and C11—C10—N1—N2 = -1.0 (3), with a maximum deviation of 0.0056 (18)Å for atom N1.The bond lengths of B—F bonds are ranged from 1.343 (3) to 1.385 (3) Å, and the bond angles of F—B—F are ranged from 108.9 (2) to 111.4 (3)°.

Related literature top

For background, reviews and literature related to N-heterocyclic carbenes, see: Arduengo et al. (1991); Arduengo (1999); Wurtz et al. (2008); Haque et al. (2010).

Experimental top

A mixture of 1-ethyl-3-(2,4,6-trimethylphenyl)imidazolium bromide (295.2 mg, 1 mmol) and sodium tetrafluoroborate (142 mg, 1.3 mmol) in THF(10 ml) was stirred for 4 h. The formed precipitate was separated by filtration and washed with Et2O and water, dried under vacuum to give an white powder (272 mg). Crystals appropriate for data collection were obtained by slow diffusion of hexane into a solution of the the title compound in dichloromethane at 293 K.

Refinement top

All H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms with C—H = 0.93 or 0.97 Å; with Uiso(H) = 1.2 or 1.5Ueq(C).

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); 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 (I), with atom labels and 50% probability displacement ellipsoids for non-H atoms. H atoms are represented by circles of arbitrary size.
[Figure 2] Fig. 2. The packing of (I), viewed down the c axis, showing one layer of molecules connected by C—H···F hydrogen bonds (dashed lines).
1-Ethyl-3-(2,4,6-trimethylphenyl)imidazolium tetrafluoroborate top
Crystal data top
C14H19N2+·BF4−F(000) = 632
Mr = 302.12Dx = 1.309 Mg m−3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 3305 reflections
a = 7.7637 (7) Åθ = 2.4–26.5°
b = 9.1625 (9) ŵ = 0.11 mm−1
c = 21.559 (2) ÅT = 298 K
β = 91.401 (2)°Block, colourless
V = 1533.2 (2) Å30.16 × 0.15 × 0.10 mm
Z = 4
Data collection top
Bruker SMART CCD area-detector
diffractometer		3013 independent reflections
Radiation source: fine-focus sealed tube2610 reflections with I > 2σ(I)
graphiteRint = 0.026
phi and ω scansθmax = 26.0°, θmin = 1.9°
Absorption correction: multi-scan
(SADABS; Sheldrick, 2004)		h = −9→9
Tmin = 0.983, Tmax = 0.989k = −11→9
9593 measured reflectionsl = −25→26
Refinement top
Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.067H-atom parameters constrained
wR(F2) = 0.181 w = 1/[σ2(Fo2) + (0.0826P)2 + 0.7775P]
where P = (Fo2 + 2Fc2)/3
S = 1.08(Δ/σ)max = 0.026
3013 reflectionsΔρmax = 0.30 e Å−3
195 parametersΔρmin = −0.26 e Å−3
0 restraintsExtinction correction: SHELXS97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.014 (3)
Crystal data top
C14H19N2+·BF4−V = 1533.2 (2) Å3
Mr = 302.12Z = 4
Monoclinic, P21/nMo Kα radiation
a = 7.7637 (7) ŵ = 0.11 mm−1
b = 9.1625 (9) ÅT = 298 K
c = 21.559 (2) Å0.16 × 0.15 × 0.10 mm
β = 91.401 (2)°
Data collection top
Bruker SMART CCD area-detector
diffractometer		3013 independent reflections
Absorption correction: multi-scan
(SADABS; Sheldrick, 2004)		2610 reflections with I > 2σ(I)
Tmin = 0.983, Tmax = 0.989Rint = 0.026
9593 measured reflectionsθmax = 26.0°
Refinement top
R[F2 > 2σ(F2)] = 0.067H-atom parameters constrained
wR(F2) = 0.181Δρmax = 0.30 e Å−3
S = 1.08Δρmin = −0.26 e Å−3
3013 reflectionsAbsolute structure: ?
195 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
B10.3268 (4)0.6442 (3)0.16502 (13)0.0525 (7)
C10.7628 (3)0.8458 (2)0.04243 (9)0.0430 (5)
C20.7570 (3)0.7075 (3)0.01582 (11)0.0537 (6)
C30.7342 (3)0.7003 (3)−0.04830 (11)0.0580 (6)
H30.73030.6093−0.06740.070*
C40.7172 (3)0.8245 (3)−0.08467 (10)0.0506 (6)
C50.7239 (3)0.9592 (3)−0.05564 (10)0.0459 (5)
H50.71171.0429−0.07970.055*
C60.7481 (3)0.9738 (2)0.00784 (10)0.0428 (5)
C70.7746 (5)0.5706 (3)0.05432 (14)0.0803 (9)
H7A0.75880.48670.02810.120*
H7B0.68900.57050.08570.120*
H7C0.88730.56740.07360.120*
C80.6908 (4)0.8130 (4)−0.15396 (12)0.0704 (8)
H8A0.57040.8002−0.16370.106*
H8B0.75400.7308−0.16910.106*
H8C0.73110.9005−0.17330.106*
C90.7608 (3)1.1231 (3)0.03680 (12)0.0576 (6)
H9A0.74851.19610.00510.086*
H9B0.87091.13370.05750.086*
H9C0.67101.13460.06630.086*
C100.9442 (3)0.8499 (3)0.14103 (11)0.0585 (7)
H101.05030.82780.12430.070*
C110.9149 (3)0.8783 (3)0.20014 (11)0.0560 (6)
H110.99680.88060.23230.067*
C120.6688 (3)0.8903 (2)0.14954 (10)0.0432 (5)
H120.55190.90120.14030.052*
C130.6504 (3)0.9378 (3)0.26280 (10)0.0535 (6)
H13A0.53050.95830.25260.064*
H13B0.70041.02480.28150.064*
C140.6599 (4)0.8162 (3)0.30850 (12)0.0694 (8)
H14A0.61020.72990.29030.104*
H14B0.59740.84250.34470.104*
H14C0.77810.79790.32000.104*
F10.3231 (3)0.6699 (2)0.10302 (8)0.1034 (7)
F20.4792 (3)0.5802 (3)0.18106 (10)0.1111 (8)
F30.3132 (2)0.7798 (2)0.19293 (8)0.0817 (6)
F40.1928 (3)0.5595 (2)0.17995 (13)0.1228 (9)
N10.7890 (2)0.8590 (2)0.10897 (8)0.0433 (4)
N20.7417 (2)0.9036 (2)0.20523 (8)0.0431 (4)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
B10.0531 (15)0.0509 (15)0.0534 (15)0.0004 (12)0.0011 (12)0.0059 (12)
C10.0453 (11)0.0476 (12)0.0360 (10)0.0015 (9)0.0028 (8)0.0006 (9)
C20.0673 (15)0.0429 (13)0.0512 (13)0.0039 (11)0.0072 (11)0.0013 (10)
C30.0739 (17)0.0475 (13)0.0527 (14)0.0036 (12)0.0044 (11)−0.0124 (11)
C40.0488 (12)0.0596 (14)0.0434 (12)0.0042 (10)0.0019 (9)−0.0033 (10)
C50.0456 (12)0.0490 (13)0.0430 (11)0.0031 (9)0.0014 (9)0.0061 (9)
C60.0402 (11)0.0445 (12)0.0437 (11)0.0005 (9)0.0018 (8)−0.0006 (9)
C70.124 (3)0.0468 (15)0.0703 (19)0.0093 (16)0.0099 (17)0.0075 (13)
C80.0803 (19)0.083 (2)0.0475 (14)0.0079 (15)−0.0039 (12)−0.0100 (13)
C90.0716 (16)0.0459 (13)0.0553 (14)−0.0023 (11)0.0002 (11)−0.0014 (11)
C100.0392 (12)0.0832 (19)0.0530 (14)0.0065 (11)0.0012 (10)0.0082 (12)
C110.0452 (12)0.0752 (17)0.0474 (13)0.0004 (11)−0.0066 (10)0.0069 (12)
C120.0388 (11)0.0475 (12)0.0432 (11)0.0033 (9)0.0008 (8)0.0009 (9)
C130.0626 (14)0.0561 (14)0.0421 (12)0.0027 (11)0.0047 (10)−0.0088 (10)
C140.0866 (19)0.0722 (18)0.0500 (14)0.0049 (15)0.0156 (13)0.0078 (13)
F10.1536 (19)0.0988 (14)0.0573 (11)0.0246 (13)−0.0050 (11)0.0061 (9)
F20.0887 (14)0.1184 (17)0.1254 (18)0.0440 (12)−0.0116 (12)0.0259 (14)
F30.0730 (11)0.0778 (12)0.0940 (13)−0.0010 (8)−0.0021 (9)−0.0243 (9)
F40.1021 (16)0.0805 (14)0.188 (3)−0.0268 (11)0.0534 (16)0.0061 (14)
N10.0427 (9)0.0483 (10)0.0390 (9)0.0030 (8)0.0015 (7)0.0027 (8)
N20.0475 (10)0.0443 (10)0.0375 (9)0.0014 (8)0.0010 (7)0.0009 (7)
Geometric parameters (Å, °) top
B1—F41.343 (3)C8—H8B0.9600
B1—F11.357 (3)C8—H8C0.9600
B1—F21.358 (3)C9—H9A0.9600
B1—F31.385 (3)C9—H9B0.9600
C1—C21.392 (3)C9—H9C0.9600
C1—C61.393 (3)C10—C111.326 (3)
C1—N11.449 (3)C10—N11.377 (3)
C2—C31.391 (3)C10—H100.9300
C2—C71.509 (4)C11—N21.371 (3)
C3—C41.387 (3)C11—H110.9300
C3—H30.9300C12—N21.320 (3)
C4—C51.384 (3)C12—N11.326 (3)
C4—C81.506 (3)C12—H120.9300
C5—C61.383 (3)C13—N21.478 (3)
C5—H50.9300C13—C141.488 (4)
C6—C91.506 (3)C13—H13A0.9700
C7—H7A0.9600C13—H13B0.9700
C7—H7B0.9600C14—H14A0.9600
C7—H7C0.9600C14—H14B0.9600
C8—H8A0.9600C14—H14C0.9600
F4—B1—F1109.8 (2)H8B—C8—H8C109.5
F4—B1—F2111.4 (3)C6—C9—H9A109.5
F1—B1—F2108.9 (2)C6—C9—H9B109.5
F4—B1—F3110.2 (2)H9A—C9—H9B109.5
F1—B1—F3105.8 (2)C6—C9—H9C109.5
F2—B1—F3110.6 (2)H9A—C9—H9C109.5
C2—C1—C6123.0 (2)H9B—C9—H9C109.5
C2—C1—N1119.11 (19)C11—C10—N1107.6 (2)
C6—C1—N1117.87 (19)C11—C10—H10126.2
C3—C2—C1117.1 (2)N1—C10—H10126.2
C3—C2—C7121.0 (2)C10—C11—N2107.6 (2)
C1—C2—C7121.9 (2)C10—C11—H11126.2
C4—C3—C2122.1 (2)N2—C11—H11126.2
C4—C3—H3119.0N2—C12—N1109.08 (18)
C2—C3—H3119.0N2—C12—H12125.5
C5—C4—C3118.3 (2)N1—C12—H12125.5
C5—C4—C8120.9 (2)N2—C13—C14112.4 (2)
C3—C4—C8120.8 (2)N2—C13—H13A109.1
C6—C5—C4122.5 (2)C14—C13—H13A109.1
C6—C5—H5118.8N2—C13—H13B109.1
C4—C5—H5118.8C14—C13—H13B109.1
C5—C6—C1117.1 (2)H13A—C13—H13B107.9
C5—C6—C9120.3 (2)C13—C14—H14A109.5
C1—C6—C9122.62 (19)C13—C14—H14B109.5
C2—C7—H7A109.5H14A—C14—H14B109.5
C2—C7—H7B109.5C13—C14—H14C109.5
H7A—C7—H7B109.5H14A—C14—H14C109.5
C2—C7—H7C109.5H14B—C14—H14C109.5
H7A—C7—H7C109.5C12—N1—C10107.65 (18)
H7B—C7—H7C109.5C12—N1—C1125.94 (18)
C4—C8—H8A109.5C10—N1—C1126.31 (18)
C4—C8—H8B109.5C12—N2—C11108.11 (18)
H8A—C8—H8B109.5C12—N2—C13125.41 (19)
C4—C8—H8C109.5C11—N2—C13126.47 (19)
H8A—C8—H8C109.5
C6—C1—C2—C3−0.4 (4)N1—C10—C11—N20.6 (3)
N1—C1—C2—C3−179.0 (2)N2—C12—N1—C101.0 (3)
C6—C1—C2—C7179.5 (3)N2—C12—N1—C1−175.53 (19)
N1—C1—C2—C70.9 (4)C11—C10—N1—C12−1.0 (3)
C1—C2—C3—C4−0.3 (4)C11—C10—N1—C1175.5 (2)
C7—C2—C3—C4179.8 (3)C2—C1—N1—C12−103.7 (3)
C2—C3—C4—C50.2 (4)C6—C1—N1—C1277.7 (3)
C2—C3—C4—C8−179.3 (2)C2—C1—N1—C1080.4 (3)
C3—C4—C5—C60.5 (3)C6—C1—N1—C10−98.3 (3)
C8—C4—C5—C6−179.9 (2)N1—C12—N2—C11−0.7 (3)
C4—C5—C6—C1−1.1 (3)N1—C12—N2—C13−179.9 (2)
C4—C5—C6—C9177.8 (2)C10—C11—N2—C120.0 (3)
C2—C1—C6—C51.1 (3)C10—C11—N2—C13179.2 (2)
N1—C1—C6—C5179.73 (18)C14—C13—N2—C12115.6 (3)
C2—C1—C6—C9−177.8 (2)C14—C13—N2—C11−63.4 (3)
N1—C1—C6—C90.8 (3)
Acknowledgements top

The authors acknowledge financial support from the National Natural Science Foundation of China (No. 20572029), the New Century Excellent Talents in Universities (NCET-04–0743) and the Cultivation Fund of the Key Scientific and Technical Innovation Project, Ministry of Education of China (No. 705039).

references
References top

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