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Acta Crystallogr Sect E Struct Rep Online. 2009 August 1; 65(Pt 8): o1829.
Published online 2009 July 11. doi:  10.1107/S1600536809026312
PMCID: PMC2977162

1,1′,2,2′-Tetra­methyl-3,3′-(p-phenyl­enedimethyl­ene)diimidazol-1-ium bis­(tetra­fluoridoborate)

Abstract

The title imidazolium-based ionic-liquid salt, C18H24N4 2+·2BF4 , has the cation lying about a center of inversion. The five-membered imidazole ring is approximately perpendicular to the six-membered phenyl­ene ring [dihedral angle = 86.9 (1)°]. The tetra­fluoro­borate anion is disordered over two sites in a 0.722 (3):0.278 (3) ratio.

Related literature

For background to imidazolium-based ionic liquid salts, see: Ganesan et al. (2008 [triangle]).

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Object name is e-65-o1829-scheme1.jpg

Experimental

Crystal data

  • C18H24N4 2+·2BF4
  • M r = 470.03
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-65-o1829-efi1.jpg
  • a = 8.9095 (2) Å
  • b = 10.2254 (2) Å
  • c = 11.7113 (3) Å
  • β = 93.024 (1)°
  • V = 1065.45 (4) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.14 mm−1
  • T = 140 K
  • 0.40 × 0.35 × 0.05 mm

Data collection

  • Bruker SMART APEX diffractometer
  • Absorption correction: multi-scan (SADABS; Sheldrick, 1996 [triangle]) T min = 0.948, T max = 0.993
  • 7256 measured reflections
  • 2418 independent reflections
  • 2063 reflections with I > 2σ(I)
  • R int = 0.017

Refinement

  • R[F 2 > 2σ(F 2)] = 0.047
  • wR(F 2) = 0.140
  • S = 1.03
  • 2418 reflections
  • 193 parameters
  • 124 restraints
  • H-atom parameters constrained
  • Δρmax = 0.42 e Å−3
  • Δρmin = −0.22 e Å−3

Data collection: APEX2 (Bruker, 2008 [triangle]); cell refinement: SAINT (Bruker, 2008 [triangle]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: X-SEED (Barbour, 2001 [triangle]); software used to prepare material for publication: publCIF (Westrip, 2009 [triangle]).

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536809026312/tk2495sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536809026312/tk2495Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

We thank the University of Malaya (grant Nos. TA 0009/2008 A and FS343/2008 A) for supporting this study.

supplementary crystallographic information

Experimental

α,α-Dibromo-p-xylene (0.78 g, 3 mmol) and 1,2-dimethylimidazole (0.58 g, 6 mmol) were refluxed in DMF (50 ml) for 3 h. The product that separated from solution was collected and washed with ether. Crystals were grown from its solution in water.

The bromide salt (0.46 g, 1 mmol) and sodium tetrafluoroborate (0.11 g, 1 mol) were stirred in water (100 ml) for 24 h. The product that separated from solution was collected and washed with ethanol. Crystals were grown from its solution in DMF.

Refinement

The [BF4]- anion is disordered in both the boron and fluorine atoms. The B–F distances were restrained to within 0.01 Å as were the F···F distances. The disorder refined to a 0.722 (3):0.278 (3) ratio. The anisotropic displacement parameters of the minor component atoms were restrained to be nearly isotropic. The F–B–F angles, although not ideal, are regarded as being satisfactory.

Carbon-bound H-atoms were placed in calculated positions (C—H 0.95 to 0.99 Å) and were included in the refinement in the riding model approximation, with U(H) set to 1.2 to 1.5Ueq(C).

Figures

Fig. 1.
Thermal ellipsoid plot (Barbour, 2001) of [C18H24N4]2+ 2[BF4]- at the 70% probability level; hydrogen atoms are drawn as spheres of arbitrary radius. The [BF4]- anion is disordered; the minor component of the disorder is not shown. The non-H atoms comprising ...

Crystal data

C18H24N42+·2BF4F(000) = 484
Mr = 470.03Dx = 1.465 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 3223 reflections
a = 8.9095 (2) Åθ = 2.6–28.2°
b = 10.2254 (2) ŵ = 0.14 mm1
c = 11.7113 (3) ÅT = 140 K
β = 93.024 (1)°Irregular block, colorless
V = 1065.45 (4) Å30.40 × 0.35 × 0.05 mm
Z = 2

Data collection

Bruker SMART APEX diffractometer2418 independent reflections
Radiation source: fine-focus sealed tube2063 reflections with I > 2σ(I)
graphiteRint = 0.017
ω scansθmax = 27.5°, θmin = 2.7°
Absorption correction: multi-scan (SADABS; Sheldrick, 1996)h = −11→11
Tmin = 0.948, Tmax = 0.993k = −12→13
7256 measured reflectionsl = −15→15

Refinement

Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.047Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.140H-atom parameters constrained
S = 1.03w = 1/[σ2(Fo2) + (0.0793P)2 + 0.4801P] where P = (Fo2 + 2Fc2)/3
2418 reflections(Δ/σ)max < 0.001
193 parametersΔρmax = 0.42 e Å3
124 restraintsΔρmin = −0.22 e Å3

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/UeqOcc. (<1)
F10.5880 (4)0.1389 (5)0.7595 (4)0.0560 (16)0.722 (3)
F20.3734 (4)0.1621 (3)0.8509 (2)0.0798 (12)0.722 (3)
F30.4339 (3)−0.0345 (2)0.7799 (3)0.0564 (7)0.722 (3)
F40.3648 (2)0.1294 (2)0.66391 (16)0.0572 (6)0.722 (3)
F1'0.5870 (8)0.1500 (9)0.7551 (6)0.025 (2)0.278 (3)
F2'0.3434 (6)0.1720 (6)0.7957 (7)0.065 (2)0.278 (3)
F3'0.4968 (6)0.0503 (6)0.9079 (4)0.0664 (17)0.278 (3)
F4'0.4287 (12)−0.0201 (7)0.7334 (7)0.099 (4)0.278 (3)
N10.53432 (15)0.55200 (13)0.81766 (11)0.0262 (3)
N20.69734 (16)0.64335 (14)0.93417 (11)0.0278 (3)
C10.38756 (18)0.46412 (16)0.41995 (14)0.0277 (4)
H10.31010.43920.36550.033*
C20.36751 (18)0.44717 (16)0.53553 (14)0.0275 (4)
H20.27610.41100.55950.033*
C30.47960 (17)0.48256 (14)0.61695 (13)0.0247 (3)
C40.4550 (2)0.45769 (16)0.74175 (14)0.0291 (4)
H4A0.34600.46210.75410.035*
H4B0.49000.36830.76190.035*
C70.66006 (18)0.53075 (16)0.88270 (13)0.0264 (4)
C90.7447 (2)0.40622 (18)0.89444 (17)0.0382 (4)
H9A0.67740.33290.87490.057*
H9B0.78500.39660.97350.057*
H9C0.82770.40690.84270.057*
C80.8332 (2)0.66710 (19)1.00765 (15)0.0368 (4)
H8A0.84370.59821.06570.055*
H8B0.82520.75221.04530.055*
H8C0.92140.66670.96110.055*
C60.5949 (2)0.73843 (17)0.89965 (15)0.0324 (4)
H60.59620.82740.92290.039*
C50.4932 (2)0.68179 (17)0.82714 (15)0.0322 (4)
H50.40890.72300.78940.039*
B10.4413 (4)0.0981 (4)0.7654 (3)0.0246 (8)0.722 (3)
B1'0.4639 (8)0.0891 (8)0.7968 (6)0.026 (3)0.278 (3)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
F10.033 (3)0.057 (2)0.077 (3)−0.0039 (17)−0.0074 (19)0.0112 (18)
F20.123 (3)0.0547 (16)0.0673 (16)−0.0125 (16)0.0595 (18)−0.0215 (14)
F30.0532 (13)0.0217 (9)0.095 (2)0.0044 (8)0.0083 (13)0.0100 (11)
F40.0433 (10)0.0755 (13)0.0509 (11)−0.0056 (9)−0.0156 (8)0.0165 (9)
F1'0.024 (5)0.027 (3)0.025 (3)−0.003 (3)0.005 (3)−0.006 (2)
F2'0.0158 (19)0.035 (2)0.146 (7)0.0079 (17)0.016 (3)0.011 (4)
F3'0.068 (3)0.086 (4)0.047 (3)0.011 (3)0.009 (2)0.009 (2)
F4'0.092 (5)0.082 (6)0.123 (7)−0.031 (5)0.011 (5)−0.072 (5)
N10.0254 (7)0.0273 (7)0.0257 (7)0.0001 (5)−0.0009 (5)0.0001 (5)
N20.0284 (7)0.0327 (7)0.0223 (6)−0.0002 (5)0.0007 (5)−0.0026 (5)
C10.0228 (8)0.0289 (8)0.0305 (8)−0.0023 (6)−0.0060 (6)−0.0037 (6)
C20.0214 (8)0.0275 (8)0.0334 (8)−0.0034 (6)−0.0007 (6)−0.0019 (6)
C30.0241 (7)0.0201 (7)0.0294 (8)0.0014 (6)−0.0028 (6)−0.0015 (6)
C40.0296 (8)0.0268 (8)0.0303 (8)−0.0052 (6)−0.0047 (6)0.0003 (6)
C70.0279 (8)0.0297 (8)0.0215 (7)0.0009 (6)0.0011 (6)0.0010 (6)
C90.0391 (10)0.0313 (9)0.0432 (10)0.0078 (7)−0.0079 (8)0.0001 (7)
C80.0362 (9)0.0441 (10)0.0291 (8)−0.0030 (8)−0.0075 (7)−0.0070 (7)
C60.0351 (9)0.0283 (8)0.0338 (9)0.0043 (7)0.0031 (7)−0.0039 (7)
C50.0320 (9)0.0290 (8)0.0353 (9)0.0061 (7)−0.0013 (7)0.0007 (7)
B10.0270 (16)0.0229 (14)0.0234 (18)0.0008 (11)−0.0033 (14)−0.0002 (12)
B1'0.022 (4)0.032 (4)0.023 (5)0.005 (3)−0.012 (3)−0.006 (3)

Geometric parameters (Å, °)

F1—B11.377 (4)C2—C31.392 (2)
F2—B11.364 (4)C2—H20.9500
F3—B11.368 (4)C3—C1i1.392 (2)
F4—B11.376 (4)C3—C41.511 (2)
F1'—B1'1.373 (7)C4—H4A0.9900
F2'—B1'1.368 (6)C4—H4B0.9900
F3'—B1'1.377 (6)C7—C91.483 (2)
F4'—B1'1.368 (7)C9—H9A0.9800
N1—C71.339 (2)C9—H9B0.9800
N1—C51.383 (2)C9—H9C0.9800
N1—C41.467 (2)C8—H8A0.9800
N2—C71.333 (2)C8—H8B0.9800
N2—C61.379 (2)C8—H8C0.9800
N2—C81.468 (2)C6—C51.340 (2)
C1—C21.386 (2)C6—H60.9500
C1—C3i1.392 (2)C5—H50.9500
C1—H10.9500
C7—N1—C5109.11 (14)C7—C9—H9C109.5
C7—N1—C4126.85 (14)H9A—C9—H9C109.5
C5—N1—C4123.94 (14)H9B—C9—H9C109.5
C7—N2—C6109.33 (14)N2—C8—H8A109.5
C7—N2—C8125.87 (15)N2—C8—H8B109.5
C6—N2—C8124.58 (15)H8A—C8—H8B109.5
C2—C1—C3i120.51 (14)N2—C8—H8C109.5
C2—C1—H1119.7H8A—C8—H8C109.5
C3i—C1—H1119.7H8B—C8—H8C109.5
C1—C2—C3120.79 (15)C5—C6—N2107.20 (15)
C1—C2—H2119.6C5—C6—H6126.4
C3—C2—H2119.6N2—C6—H6126.4
C2—C3—C1i118.69 (15)C6—C5—N1107.02 (15)
C2—C3—C4118.92 (14)C6—C5—H5126.5
C1i—C3—C4122.36 (14)N1—C5—H5126.5
N1—C4—C3112.68 (13)F2—B1—F3111.0 (3)
N1—C4—H4A109.1F2—B1—F4107.7 (3)
C3—C4—H4A109.1F3—B1—F4108.2 (3)
N1—C4—H4B109.1F2—B1—F1110.5 (3)
C3—C4—H4B109.1F3—B1—F1111.0 (3)
H4A—C4—H4B107.8F4—B1—F1108.3 (3)
N2—C7—N1107.34 (14)F2'—B1'—F4'110.1 (6)
N2—C7—C9125.89 (15)F2'—B1'—F1'110.9 (6)
N1—C7—C9126.76 (15)F4'—B1'—F1'110.0 (6)
C7—C9—H9A109.5F2'—B1'—F3'108.4 (6)
C7—C9—H9B109.5F4'—B1'—F3'108.0 (6)
H9A—C9—H9B109.5F1'—B1'—F3'109.5 (6)
C3i—C1—C2—C3−0.2 (3)C8—N2—C7—C93.3 (3)
C1—C2—C3—C1i0.2 (3)C5—N1—C7—N21.03 (18)
C1—C2—C3—C4−177.78 (15)C4—N1—C7—N2177.39 (14)
C7—N1—C4—C3−104.65 (18)C5—N1—C7—C9−177.97 (17)
C5—N1—C4—C371.2 (2)C4—N1—C7—C9−1.6 (3)
C2—C3—C4—N1−150.75 (15)C7—N2—C6—C50.69 (19)
C1i—C3—C4—N131.3 (2)C8—N2—C6—C5175.47 (16)
C6—N2—C7—N1−1.06 (18)N2—C6—C5—N1−0.05 (19)
C8—N2—C7—N1−175.76 (15)C7—N1—C5—C6−0.61 (19)
C6—N2—C7—C9177.95 (17)C4—N1—C5—C6−177.10 (15)

Symmetry codes: (i) −x+1, −y+1, −z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: TK2495).

References

  • Barbour, L. J. (2001). J. Supramol. Chem.1, 189–191.
  • Bruker (2008). APEX2 and SAINT Bruker AXS Inc., Madison, Wisconsin, USA.
  • Ganesan, K., Alias, Y. & Ng, S. W. (2008). Acta Cryst. C64, o478–o480. [PubMed]
  • Sheldrick, G. M. (1996). SADABS University of Göttingen, Germany.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]
  • Westrip, S. P. (2009). publCIF In preparation.

Articles from Acta Crystallographica Section E: Structure Reports Online are provided here courtesy of International Union of Crystallography