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organic compounds\(\def\hfill{\hskip 5em}\def\hfil{\hskip 3em}\def\eqno#1{\hfil {#1}}\)

Journal logoCRYSTALLOGRAPHIC
COMMUNICATIONS
ISSN: 2056-9890
Volume 66| Part 6| June 2010| Page o1267
https://doi.org/10.1107/S160053681001593X

3,3′-Di­methyl-1,1′-(butane-1,4-di­yl)diimidazolium bis­­(tetra­fluoro­borate)

Hao Geng,a Ling-hua Zhuang,b Jian Zhang,a Guo-wei Wanga* and Ai-lin Yuana

aDepartment of Light Chemical Engineering, College of Food Science and Light Engineering, Nanjing University of Technology, Nanjing 210009, People's Republic of China, and bDepartment of Applied Chemistry, College of Science, Nanjing University of Technology, Nanjing 210009, People's Republic of China
*Correspondence e-mail: kingwell2004@sina.com.cn

(Received 28 April 2010; accepted 30 April 2010; online 8 May 2010)

The title compound, C12H20N42+·2BF4−, was prepared by the anion exchange of a dibromide ionic liquid with sodium tetra­fluoro­borate. The asymmetric unit contains one half of the imidazolium cation, which lies about an inversion centre at the mid-point of the central C—C bond of the linking butyl chain. The two planar imidazole rings (r.m.s. deviation = 0.0013 Å) are strictly parallel and separated by 2.625 (7) Å [vertical distance between the centroids of two imidazole rings], giving the mol­ecule a stepped appearance. In the crystal structure, inter­molecular C—H⋯F hydrogen bonds link the cations and anions, generating a three-dimensional network.

Related literature

For properties and applications of ionic liquids, see: Welton (1999[Welton, T. (1999). Chem. Rev. 99, 2071-2083.]); Olivier & Magna (2002[Olivier, H. B. & Magna, L. (2002). J. Mol. Catal. A Chem. 182-183, 419-437.]); Nicholas et al. (2004[Nicholas, G., Garcia, M. T. & Scammells, P. J. (2004). Green Chem. 6, 166-175.]); Yu et al.(2007[Yu, G. Q., Yan, S. Q., Zhou, F., Liu, X. Q., Liu, W. M. & Liang, Y. M. (2007). Tribology Lett. 25, 197-205.]). For dicationic ionic liquids, see: Leclercq et al. (2007[Leclercq, L., Suisse, I., Nowogrocki, G. & Agbossou-Niedercorn, F. (2007). Green Chem. 9, 1097-1103.]); Payagala et al. (2007[Payagala, T., Huang, J. M., Breitbach, Z. S., Sharma, P. S. & Armstrong, D. W. (2007). Chem. Mater. 19, 5848-5850.]). For bond-length data, see: Allen et al. (1987[Allen, F. H., Kennard, O., Watson, D. G., Brammer, L., Orpen, A. G. & Taylor, R. (1987). J. Chem. Soc. Perkin Trans. 2, pp. S1-19.]).

[Scheme 1]

Experimental

Crystal data

  • C12H20N42+·2BF4−

  • Mr = 393.94

  • Monoclinic, P 21 /c

  • a = 5.195 (1) Å

  • b = 14.836 (3) Å

  • c = 11.790 (2) Å

  • β = 99.53 (3)°

  • V = 896.2 (3) Å3

  • Z = 2

  • Mo Kα radiation

  • μ = 0.15 mm−1

  • T = 293 K

  • 0.30 × 0.10 × 0.10 mm
Data collection

  • Enraf–Nonius CAD-4 diffractometer

  • Absorption correction: ψ scan (North et al., 1968[North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351-359.]) Tmin = 0.958, Tmax = 0.986

  • 1960 measured reflections

  • 1763 independent reflections

  • 1125 reflections with I > 2σ(I)

  • Rint = 0.019

  • 3 standard reflections every 200 reflections intensity decay: 1%
Refinement

  • R[F2 > 2σ(F2)] = 0.046

  • wR(F2) = 0.155

  • S = 1.01

  • 1763 reflections

  • 119 parameters

  • H-atom parameters constrained

  • Δρmax = 0.20 e Å−3

  • Δρmin = −0.19 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A D⋯A D—H⋯A
C2—H2A⋯F1i 0.93 2.50 3.328 (3) 149
C3—H3A⋯F3ii 0.93 2.51 3.398 (3) 161
C4—H4A⋯F2iii 0.93 2.46 3.272 (3) 146
C4—H4A⋯F3iii 0.93 2.45 3.326 (3) 158
Symmetry codes: (i) [x, -y+{\script{1\over 2}}, z+{\script{1\over 2}}]; (ii) [-x+1, y-{\script{1\over 2}}, -z+{\script{3\over 2}}]; (iii) x+1, y, z.

Data collection: CAD-4 Software (Enraf–Nonius, 1989[Enraf-Nonius (1989). CAD-4 Software. Enraf-Nonius, Delft, The Netherlands.]); cell refinement: CAD-4 Software; data reduction: XCAD4 (Harms & Wocadlo, 1995[Harms, K. & Wocadlo, S. (1995). XCAD4. University of Marburg, Germany.]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); software used to prepare material for publication: SHELXTL.

Supporting information

Crystal structure: contains datablocks global, I. DOI: https://doi.org/10.1107/S160053681001593X/sj2792sup1.cif

Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S160053681001593X/sj2792Isup2.hkl

checkCIF report


Comment top

Ionic liquids (ILs) are generally formed by an organic cation and a weakly coordinating anion. They have enjoyed considerable research interest in recent years because of their unique properties such as high thermal stability, non-volatility, non-flammability, high ionic conductivity, a wide electrochemical window and miscibility with organic compounds (Welton, 1999; Nicholas et al., 2004; Yu et al., 2007). ILs have been widely applied to several areas including catalysis, electrochemistry, separation science, as solvents for green chemistry, biology and materials for optoelectronic applications (Olivier & Magna, 2002). Geminal dicationic ionic liquids have been shown to possess superior physical properties in terms of thermal stability and volatility compared to traditional ionic liquids (ILs) (Leclercq et al., 2007; Payagala et al., 2007) .

We here report the crystal structure of the title compound (I).

The atom-numbering scheme of (I) is shown in Fig.1, and all bond lengths are within normal ranges (Allen et al., 1987).

The imidazole ring (C2/C3/N2/C4/N1) is planar, with r.m.s. deviation 0.0013 Å. The two imidazole rings are strictly parallel.

In the crystal structure intermolecular C—H···F hydrogen bonds link the cations and anions generating a three-dimensional network. (Table 1 and Fig.2). ).

Related literature top

For properties and applications of ionic liquids, see: Welton (1999); Olivier & Magna (2002); Nicholas et al. (2004); Yu et al.(2007). For dicationic ionic liquids, see: Leclercq et al. (2007); Payagala et al. (2007). For bond-length data, see: Allen et al. (1987).

Experimental top

A solution of 1,4-dibromobutane(4.3 g, 0.02 mol) in methanol(20 ml) was slowly added to a solution of 1-methylimidazole(3.28 g, 0.04 mol) in methanol(20 ml) at room temperature. The reaction mixture was then refluxed for 6 h. After evaporation of the solvent, the residue was washed with diethyl ether and dichloromethane, then dried in vacuum to obtain ionic liquid 3-methyl-1-[4-(1-methylimidazolium-3-yl) butyl]-imidazolium dibromide (a white solid ionic liquid).

A solution of above mentioned dibromide ionic liquid (3.8 g, 0.01 mol) in methanol(20 ml) was slowly added to a solution of sodium tetrafluoroborate (2.2 g, 0.02 mol) in methanol (20 ml), The reaction mixture was refluxed for 1 h. After evaporation of the solvent, the residue was washed with diethyl ether, then dried in vacuum to obtain title compound (I), 3-methyl-1-[4-(1-methylimidazolium-3-yl) butyl]- imidazolium ditetrafluoroborate(yield 94%). M.p. 95-97

Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of a methanol solution. 1H NMR (D2O, δ, p.p.m.) 8.67 (s, 2 H), 7.43 (d, 4 H), 4.23 (s, 4 H), 3.87 (s,6 H), 1.88 (s, 4 H).

Refinement top

All H atoms were positioned geometrically, with C—H = 0.93 Å, and constrained to ride on their parent atoms, with Uiso(H) = xUeq(C), where x= 1.5 for methyl H and x = 1.2 for methylene H atoms.

Structure description top

Ionic liquids (ILs) are generally formed by an organic cation and a weakly coordinating anion. They have enjoyed considerable research interest in recent years because of their unique properties such as high thermal stability, non-volatility, non-flammability, high ionic conductivity, a wide electrochemical window and miscibility with organic compounds (Welton, 1999; Nicholas et al., 2004; Yu et al., 2007). ILs have been widely applied to several areas including catalysis, electrochemistry, separation science, as solvents for green chemistry, biology and materials for optoelectronic applications (Olivier & Magna, 2002). Geminal dicationic ionic liquids have been shown to possess superior physical properties in terms of thermal stability and volatility compared to traditional ionic liquids (ILs) (Leclercq et al., 2007; Payagala et al., 2007) .

We here report the crystal structure of the title compound (I).

The atom-numbering scheme of (I) is shown in Fig.1, and all bond lengths are within normal ranges (Allen et al., 1987).

The imidazole ring (C2/C3/N2/C4/N1) is planar, with r.m.s. deviation 0.0013 Å. The two imidazole rings are strictly parallel.

In the crystal structure intermolecular C—H···F hydrogen bonds link the cations and anions generating a three-dimensional network. (Table 1 and Fig.2). ).

For properties and applications of ionic liquids, see: Welton (1999); Olivier & Magna (2002); Nicholas et al. (2004); Yu et al.(2007). For dicationic ionic liquids, see: Leclercq et al. (2007); Payagala et al. (2007). For bond-length data, see: Allen et al. (1987).

Computing details top

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); 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. A view of the molecular structure of (I) showing the atom-numbering scheme and 30 % displacement ellipsoids .
[Figure 2] Fig. 2. The crystal packing of (I), Hydrogen bonds are drawn as dashed lines. Symmetry codes a) x,1/2-y,1/2+z; b) 1-x,-1/2+y,3/2-z; c) 1+x,y,z
3,3'-Dimethyl-1,1'-(butane-1,4-diyl)diimidazolium bis(tetrafluoroborate) top
Crystal data top
C12H20N42+·2BF4−F(000) = 404
Mr = 393.94Dx = 1.460 Mg m−3
Monoclinic, P21/cMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybcCell parameters from 25 reflections
a = 5.195 (1) Åθ = 9–13°
b = 14.836 (3) ŵ = 0.15 mm−1
c = 11.790 (2) ÅT = 293 K
β = 99.53 (3)°Block, colorless
V = 896.2 (3) Å30.30 × 0.10 × 0.10 mm
Z = 2
Data collection top
Enraf–Nonius CAD-4
diffractometer		1125 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.019
Graphite monochromatorθmax = 26.0°, θmin = 2.2°
ω/2θ scansh = 0→6
Absorption correction: ψ scan
(North et al., 1968)		k = 0→18
Tmin = 0.958, Tmax = 0.986l = −14→14
1960 measured reflections3 standard reflections every 200 reflections
1763 independent reflections intensity decay: 1%
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)] = 0.046H-atom parameters constrained
wR(F2) = 0.155 w = 1/[σ2(Fo2) + (0.085P)2]
where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max < 0.001
1763 reflectionsΔρmax = 0.20 e Å−3
119 parametersΔρmin = −0.19 e Å−3
0 restraintsExtinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4
Primary atom site location: structure-invariant direct methodsExtinction coefficient: 0.105 (11)
Crystal data top
C12H20N42+·2BF4−V = 896.2 (3) Å3
Mr = 393.94Z = 2
Monoclinic, P21/cMo Kα radiation
a = 5.195 (1) ŵ = 0.15 mm−1
b = 14.836 (3) ÅT = 293 K
c = 11.790 (2) Å0.30 × 0.10 × 0.10 mm
β = 99.53 (3)°
Data collection top
Enraf–Nonius CAD-4
diffractometer		1125 reflections with I > 2σ(I)
Absorption correction: ψ scan
(North et al., 1968)		Rint = 0.019
Tmin = 0.958, Tmax = 0.9863 standard reflections every 200 reflections
1960 measured reflections intensity decay: 1%
1763 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0460 restraints
wR(F2) = 0.155H-atom parameters constrained
S = 1.01Δρmax = 0.20 e Å−3
1763 reflectionsΔρmin = −0.19 e Å−3
119 parameters
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 > 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
N10.9683 (4)0.16123 (13)0.88401 (17)0.0515 (6)
C10.9656 (7)0.24171 (19)0.9557 (2)0.0741 (9)
H1A1.07160.28770.92960.111*
H1B1.03360.22691.03430.111*
H1C0.78970.26320.95040.111*
N21.0555 (4)0.07197 (13)0.75168 (16)0.0469 (5)
C20.8390 (5)0.08211 (17)0.8951 (2)0.0569 (7)
H2A0.73310.06950.94940.068*
C30.8937 (5)0.02637 (17)0.8132 (2)0.0549 (7)
H3A0.8334−0.03240.80020.066*
C41.0970 (5)0.15315 (16)0.7964 (2)0.0488 (6)
H4A1.19970.19750.77060.059*
C51.1592 (5)0.03798 (17)0.6510 (2)0.0544 (7)
H5A1.2626−0.01560.67260.065*
H5B1.27280.08320.62610.065*
C60.9446 (5)0.01564 (17)0.55255 (19)0.0529 (7)
H6A0.83670.06850.53270.063*
H6B0.8352−0.03150.57610.063*
B0.5724 (6)0.3204 (2)0.6816 (3)0.0585 (8)
F10.4655 (4)0.37487 (13)0.59228 (16)0.0888 (7)
F20.5357 (3)0.23068 (11)0.65187 (17)0.0857 (6)
F30.4510 (3)0.33750 (12)0.77629 (15)0.0795 (6)
F40.8355 (3)0.33695 (11)0.70959 (16)0.0822 (6)
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
N10.0566 (13)0.0546 (13)0.0433 (11)0.0030 (10)0.0081 (10)−0.0032 (9)
C10.090 (2)0.0667 (19)0.0645 (17)0.0065 (16)0.0092 (16)−0.0171 (15)
N20.0506 (12)0.0452 (11)0.0472 (10)−0.0001 (9)0.0144 (9)0.0006 (9)
C20.0621 (17)0.0584 (16)0.0546 (14)−0.0007 (13)0.0224 (13)0.0061 (12)
C30.0637 (17)0.0472 (14)0.0585 (15)−0.0084 (12)0.0233 (13)0.0030 (12)
C40.0503 (14)0.0465 (14)0.0503 (13)−0.0034 (11)0.0103 (11)0.0029 (11)
C50.0552 (15)0.0531 (14)0.0592 (15)0.0022 (12)0.0221 (12)−0.0017 (12)
C60.0595 (16)0.0468 (14)0.0565 (15)−0.0010 (11)0.0216 (13)−0.0020 (11)
B0.0488 (17)0.0561 (18)0.075 (2)−0.0012 (14)0.0230 (15)0.0105 (16)
F10.0884 (14)0.0919 (13)0.0900 (13)0.0186 (10)0.0262 (10)0.0321 (11)
F20.0812 (12)0.0622 (11)0.1163 (15)−0.0155 (9)0.0239 (11)−0.0018 (10)
F30.0691 (11)0.0908 (13)0.0856 (12)0.0016 (9)0.0330 (9)0.0107 (9)
F40.0492 (10)0.0840 (13)0.1164 (15)−0.0131 (9)0.0228 (9)0.0000 (10)
Geometric parameters (Å, º) top
N1—C41.326 (3)C4—H4A0.9300
N1—C21.369 (3)C5—C61.507 (3)
N1—C11.465 (3)C5—H5A0.9700
C1—H1A0.9600C5—H5B0.9700
C1—H1B0.9600C6—C6i1.522 (4)
C1—H1C0.9600C6—H6A0.9700
N2—C41.318 (3)C6—H6B0.9700
N2—C31.375 (3)B—F11.370 (4)
N2—C51.472 (3)B—F41.374 (3)
C2—C31.337 (3)B—F21.381 (4)
C2—H2A0.9300B—F31.394 (4)
C3—H3A0.9300
C4—N1—C2108.4 (2)N1—C4—H4A125.5
C4—N1—C1125.3 (2)N2—C5—C6112.0 (2)
C2—N1—C1126.3 (2)N2—C5—H5A109.2
N1—C1—H1A109.5C6—C5—H5A109.2
N1—C1—H1B109.5N2—C5—H5B109.2
H1A—C1—H1B109.5C6—C5—H5B109.2
N1—C1—H1C109.5H5A—C5—H5B107.9
H1A—C1—H1C109.5C5—C6—C6i111.3 (3)
H1B—C1—H1C109.5C5—C6—H6A109.4
C4—N2—C3108.2 (2)C6i—C6—H6A109.4
C4—N2—C5125.3 (2)C5—C6—H6B109.4
C3—N2—C5126.4 (2)C6i—C6—H6B109.4
C3—C2—N1107.2 (2)H6A—C6—H6B108.0
C3—C2—H2A126.4F1—B—F4109.8 (2)
N1—C2—H2A126.4F1—B—F2110.6 (3)
C2—C3—N2107.3 (2)F4—B—F2108.9 (2)
C2—C3—H3A126.3F1—B—F3109.2 (2)
N2—C3—H3A126.3F4—B—F3109.8 (3)
N2—C4—N1108.9 (2)F2—B—F3108.5 (2)
N2—C4—H4A125.5
C4—N1—C2—C30.4 (3)C5—N2—C4—N1178.3 (2)
C1—N1—C2—C3−179.9 (2)C2—N1—C4—N2−0.3 (3)
N1—C2—C3—N2−0.3 (3)C1—N1—C4—N2−180.0 (2)
C4—N2—C3—C20.2 (3)C4—N2—C5—C6−117.0 (3)
C5—N2—C3—C2−178.0 (2)C3—N2—C5—C660.9 (3)
C3—N2—C4—N10.1 (3)N2—C5—C6—C6i177.6 (2)
Symmetry code: (i) −x+2, −y, −z+1.
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···F1ii0.932.503.328 (3)149
C3—H3A···F3iii0.932.513.398 (3)161
C4—H4A···F2iv0.932.463.272 (3)146
C4—H4A···F3iv0.932.453.326 (3)158
Symmetry codes: (ii) x, −y+1/2, z+1/2; (iii) −x+1, y−1/2, −z+3/2; (iv) x+1, y, z.

Experimental details

Crystal data
Chemical formulaC12H20N42+·2BF4−
Mr393.94
Crystal system, space groupMonoclinic, P21/c
Temperature (K)293
a, b, c (Å)5.195 (1), 14.836 (3), 11.790 (2)
β (°) 99.53 (3)
V (Å3)896.2 (3)
Z2
Radiation typeMo Kα
µ (mm−1)0.15
Crystal size (mm)0.30 × 0.10 × 0.10
Data collection
DiffractometerEnraf–Nonius CAD-4
Absorption correctionψ scan
(North et al., 1968)
Tmin, Tmax0.958, 0.986
No. of measured, independent and
observed [I > 2σ(I)] reflections		1960, 1763, 1125
Rint0.019
(sin θ/λ)max (Å−1)0.616
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.155, 1.01
No. of reflections1763
No. of parameters119
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å−3)0.20, −0.19

Computer programs: CAD-4 Software (Enraf–Nonius, 1989), XCAD4 (Harms & Wocadlo, 1995), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C2—H2A···F1i0.932.503.328 (3)149.1
C3—H3A···F3ii0.932.513.398 (3)160.6
C4—H4A···F2iii0.932.463.272 (3)145.8
C4—H4A···F3iii0.932.453.326 (3)157.6
Symmetry codes: (i) x, −y+1/2, z+1/2; (ii) −x+1, y−1/2, −z+3/2; (iii) x+1, y, z.
 

Acknowledgements

This work was supported by the Foundation for Young Teachers Scholarship of Nanjing University of Technology, Jiangsu, China (grant No. 39729005). The authors also thank the Center of Testing and Analysis, Nanjing University, for the data collection.

References

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ISSN: 2056-9890
Volume 66| Part 6| June 2010| Page o1267
https://doi.org/10.1107/S160053681001593X
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