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Acta Crystallogr Sect E Struct Rep Online. 2010 December 1; 66(Pt 12): o3282.
Published online 2010 November 24. doi:  10.1107/S1600536810047677
PMCID: PMC3011425

3,3′-Dimethyl-1,1′-[(1,3-dihy­droxy­propane-2,2-di­yl)dimethyl­idene]diimidazolium bis­(hexa­fluoro­phosphate)

Abstract

The title compound, C13H22N4O2 2+·2PF6 , was prepared by the anion exchange of the dibromide ionic liquid with potassium hexa­fluoro­phosphate. The two imidazole rings are each planar (r.m.s. deviations = 0.0016 and 0.0060 Å) and make a dihedral angle of 45.3 (18)°. Intra­molecular O—H(...)F hydrogen bonds occur. Inter­molecular C—H(...)F, O—H(...)O and C—H(...)O hydrogen bonds stabilize the crystal structure.

Related literature

For properties and applications of ionic liquids, see: Welton (1999 [triangle]). For dicationic ionic liquids, see: Liang et al. (2008 [triangle]); Geng et al. (2010 [triangle]). For the synthesis of the title compound, see: Cai et al. (2007 [triangle]); Cai & Liu, (2009 [triangle]). For bond-length data, see: Allen et al., (1987 [triangle]).

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Object name is e-66-o3282-scheme1.jpg

Experimental

Crystal data

  • C13H22N4O2 2+·2PF6
  • M r = 556.29
  • Orthorhombic, An external file that holds a picture, illustration, etc.
Object name is e-66-o3282-efi3.jpg
  • a = 14.622 (3) Å
  • b = 12.504 (3) Å
  • c = 12.165 (2) Å
  • V = 2224.2 (8) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.31 mm−1
  • T = 295 K
  • 0.20 × 0.10 × 0.10 mm

Data collection

  • Enraf–Nonius CAD-4 diffractometer
  • Absorption correction: ψ scan (North et al., 1968 [triangle]) T min = 0.940, T max = 0.969
  • 4082 measured reflections
  • 2152 independent reflections
  • 1861 reflections with I > 2σ(I)
  • R int = 0.067
  • 3 standard reflections every 200 reflections intensity decay: 1%

Refinement

  • R[F 2 > 2σ(F 2)] = 0.066
  • wR(F 2) = 0.123
  • S = 1.00
  • 4082 reflections
  • 298 parameters
  • 1 restraint
  • H-atom parameters constrained
  • Δρmax = 0.20 e Å−3
  • Δρmin = −0.17 e Å−3
  • Absolute structure: Flack (1983 [triangle]), 1930 Friedel pairs
  • Flack parameter: 0.01 (16)

Data collection: CAD-4 (Enraf–Nonius, 1989 [triangle]); cell refinement: CAD-4; data reduction: XCAD4 (Harms & Wocadlo, 1995 [triangle]); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 [triangle]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 [triangle]); molecular graphics: SHELXTL (Sheldrick, 2008 [triangle]); software used to prepare material for publication: SHELXTL.

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536810047677/rk2245sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810047677/rk2245Isup2.hkl

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

Acknowledgments

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

supplementary crystallographic information

Comment

Ionic liquids (ILs) have enjoyed considerable research interests in recent years because of their unique properties (Welton, 1999). Geminal dicationic ILs have been shown to possess superior physical properties in terms of thermal stability and volatility compared to traditional ILs (Liang et al., 2008).

As part of our ongoing studies on new Geminal dicationic ILs (Geng et al., 2010), we here report the crystal structure of the title compound I.

The atom-numbering scheme of I is shown in Fig. 1. There are exist intramolecular C—H···O and O—H···F hydrogen bonds, while intermolecular C—H···F, O—H···O and C—H···O hydrogen bonds stablize the crystal structure. All bond lengths are within normal ranges (Allen et al., 1987). The imidazole ring is planar, with r.m.s. deviation 0.0016Å. The dihedral angles between two imidazole ring is 45.3 (18)°. There exist intermolecular C—H···F hydrogen bonds between hexafluorophosphate anions and imidazolium cations (Table 1, Fig. 1 and Fig. 2).

Experimental

A mixture of 1-methylimidazole (2.05 g, 25 mmol) and 2,2-bis(bromomethyl)-propane-1,3-diol (2.60 g, 10 mmol) were stirred vigorously at 423 K for 8 h. After cooling to room temperature, the crude product was washed with acetonitrile. The resulting solid collected by filtration was treated with water (20 ml) as well as KPF6 (3.68 g, 20 mmol) and the reaction mixture was stirred at room temperature for 1 h. After filtration, the white solid was washed with ethanol and dried in vacuo to give the title compound I (5.02 g, 91%)(Cai et al., 2007; Cai & Liu, 2009). M.p. 497–500 K. Crystals of I suitable for X-ray diffraction study were obtained by slow evaporation of methanol solution. 1H NMR (DMSO, δ, p.p.m.) 8.96 (s, 2 H), 7.72 (d, 2 H), 7.60 (d, 2 H), 5.29 (s, 2 H) 4.24 (s, 4 H), 3.87 (s, 6 H), 3.12 (s, 4 H).

Refinement

In the both hexafluorophosphate groups, fluorine atoms have strong oscillations, while central P atoms are fixed. All H atoms were positioned geometrically, with C—H = 0.93Å, 0.96Å and 0.97Å for aromatic, methyl, methylene H, respectively. H atoms of hydroxy-groups were positioned geometrically too with O—H = 0.82Å. During refinement these H atoms were constrained to ride on their parent atoms, with Uiso(H) = xUeq(C, O), where x = 1.2 for aromatic and methylene H atoms and x = 1.5 for methyl and hydroxyl H atoms.

Figures

Fig. 1.
A view of the molecular structure of I showing the atom-numbering scheme. Displacement ellipsoids are drawn at 30% probability level. H atoms are presented as a small spheres of arbitrary radius. Dashed lines indicate hydrogen bonds.
Fig. 2.
The crystal packing of I. Hydrogen bonds are drawn by dashed lines. Symmetry codes: (i) 2-x, 1-y, 1/2+z; (ii) -1/2+x, 1/2-y, z.

Crystal data

C13H22N4O22+·2PF6Dx = 1.661 Mg m3
Mr = 556.29Melting point = 497–500 K
Orthorhombic, Pna21Mo Kα radiation, λ = 0.71073 Å
Hall symbol: P 2c -2nCell parameters from 25 reflections
a = 14.622 (3) Åθ = 9–13°
b = 12.504 (3) ŵ = 0.31 mm1
c = 12.165 (2) ÅT = 295 K
V = 2224.2 (8) Å3Block, colourless
Z = 40.20 × 0.10 × 0.10 mm
F(000) = 1128

Data collection

Enraf–Nonius CAD-4 diffractometer1861 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.067
graphiteθmax = 25.4°, θmin = 2.1°
ω/2θ–scansh = 0→17
Absorption correction: ψ scan (North et al., 1968)k = 0→15
Tmin = 0.940, Tmax = 0.969l = −14→14
4082 measured reflections3 standard reflections every 200 reflections
2152 independent reflections intensity decay: 1%

Refinement

Refinement on F2Hydrogen site location: inferred from neighbouring sites
Least-squares matrix: fullH-atom parameters constrained
R[F2 > 2σ(F2)] = 0.066w = 1/[σ2(Fo2) + (0.034P)2] where P = (Fo2 + 2Fc2)/3
wR(F2) = 0.123(Δ/σ)max < 0.001
S = 1.00Δρmax = 0.20 e Å3
4082 reflectionsΔρmin = −0.17 e Å3
298 parametersExtinction correction: SHELXL97 (Sheldrick, 2008)
1 restraintExtinction coefficient: 0.105 (11)
Primary atom site location: structure-invariant direct methodsAbsolute structure: Flack (1983), 1930 Friedel pairs
Secondary atom site location: difference Fourier mapFlack parameter: 0.01 (16)

Special details

Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'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)

xyzUiso*/Ueq
O10.8641 (3)0.5204 (5)0.2865 (3)0.119 (2)
H1A0.81040.53620.27560.179*
N11.0848 (6)0.8302 (5)0.4610 (6)0.103 (2)
C11.1347 (5)0.9027 (6)0.5270 (7)0.123 (3)
H1B1.11270.97400.51440.185*
H1C1.19830.89890.50820.185*
H1D1.12680.88450.60300.185*
O21.0931 (3)0.4708 (3)0.5634 (3)0.0826 (14)
H2A1.10250.47400.62980.124*
N21.0515 (4)0.6773 (4)0.3942 (5)0.0724 (16)
C21.1092 (6)0.7153 (6)0.4672 (6)0.092 (3)
H2B1.15250.68040.51010.111*
N30.9585 (3)0.2977 (4)0.4254 (4)0.0595 (13)
C31.0013 (6)0.7562 (7)0.3474 (7)0.101 (2)
H3A0.95770.74670.29270.121*
N40.8598 (4)0.1738 (4)0.4570 (4)0.0708 (15)
C41.0258 (6)0.8556 (7)0.3952 (8)0.098 (3)
H4A1.00270.92330.38010.117*
C51.0500 (4)0.5689 (4)0.3557 (5)0.0593 (15)
H5A1.11080.53850.36310.071*
H5B1.03420.56840.27830.071*
C60.9823 (3)0.4998 (4)0.4183 (4)0.0402 (12)
C71.0003 (4)0.4992 (5)0.5411 (4)0.0649 (16)
H7A0.98770.56950.57120.078*
H7B0.95980.44840.57650.078*
C80.8832 (3)0.5271 (5)0.3995 (4)0.0580 (15)
H8A0.84450.47780.43980.070*
H8B0.87090.59900.42570.070*
C91.0043 (4)0.3873 (4)0.3704 (5)0.0637 (15)
H9A0.98720.38660.29340.076*
H9B1.06980.37600.37440.076*
C100.9922 (5)0.2325 (5)0.5067 (5)0.0652 (19)
H10A1.04930.23870.53970.078*
C110.9291 (5)0.1587 (6)0.5303 (6)0.081 (2)
H11A0.93200.10740.58550.098*
C120.8786 (4)0.2570 (4)0.3921 (5)0.0599 (16)
H12A0.84280.28210.33440.072*
C130.7815 (5)0.1020 (6)0.4552 (6)0.109 (3)
H13A0.73970.12430.39880.164*
H13B0.75130.10400.52520.164*
H13C0.80190.03050.44040.164*
P10.72571 (13)0.35606 (18)0.68464 (19)0.0911 (6)
F10.7669 (3)0.4744 (3)0.6875 (5)0.1535 (18)
F20.6868 (3)0.2424 (3)0.6720 (5)0.1459 (18)
F30.6246 (3)0.4001 (4)0.6840 (4)0.1420 (16)
F40.7290 (3)0.3498 (5)0.8136 (3)0.151 (2)
F50.7254 (4)0.3651 (4)0.5546 (4)0.140 (2)
F60.8266 (2)0.3132 (4)0.6825 (5)0.1478 (18)
P20.64385 (14)0.33975 (18)0.1878 (2)0.0992 (7)
F70.7457 (4)0.3277 (4)0.1659 (6)0.179 (2)
F80.6282 (7)0.3840 (8)0.0811 (7)0.355 (7)
F90.6598 (5)0.3032 (5)0.3039 (4)0.220 (3)
F100.6708 (5)0.4574 (5)0.2350 (7)0.238 (4)
F110.6079 (10)0.2399 (7)0.1625 (8)0.390 (8)
F120.5486 (5)0.3672 (9)0.2204 (9)0.314 (6)

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
O10.069 (3)0.240 (6)0.049 (2)0.047 (4)0.006 (2)0.014 (3)
N10.109 (6)0.068 (5)0.131 (6)−0.036 (5)0.018 (5)−0.028 (4)
C10.117 (7)0.105 (6)0.147 (8)−0.006 (6)0.008 (7)0.006 (6)
O20.054 (3)0.125 (4)0.069 (3)0.022 (3)−0.011 (2)−0.016 (3)
N20.065 (4)0.067 (4)0.086 (4)−0.006 (3)0.021 (3)−0.005 (3)
C20.090 (6)0.085 (6)0.102 (6)−0.023 (5)0.021 (5)−0.031 (5)
N30.063 (3)0.050 (3)0.066 (3)−0.011 (3)−0.019 (3)−0.010 (3)
C30.085 (6)0.110 (6)0.108 (6)−0.009 (6)0.028 (5)−0.005 (6)
N40.061 (3)0.087 (4)0.065 (3)−0.029 (3)−0.006 (3)0.009 (3)
C40.077 (6)0.100 (7)0.116 (8)0.008 (5)0.038 (5)0.012 (6)
C50.053 (3)0.053 (3)0.071 (4)0.004 (3)0.009 (3)0.004 (3)
C60.047 (3)0.036 (2)0.037 (3)−0.012 (3)−0.006 (3)0.005 (2)
C70.061 (4)0.092 (4)0.042 (3)0.000 (3)−0.003 (3)−0.020 (3)
C80.047 (3)0.087 (4)0.041 (3)0.021 (3)0.004 (3)0.015 (3)
C90.068 (4)0.075 (4)0.048 (3)−0.007 (4)0.005 (3)−0.002 (3)
C100.071 (5)0.052 (4)0.072 (5)−0.003 (4)−0.016 (4)0.005 (3)
C110.087 (5)0.089 (5)0.069 (5)0.014 (5)−0.003 (4)0.004 (4)
C120.067 (4)0.025 (2)0.088 (4)−0.004 (3)−0.020 (4)0.001 (3)
C130.077 (5)0.133 (7)0.118 (6)−0.067 (5)−0.007 (4)−0.008 (5)
P10.0748 (13)0.1251 (16)0.0734 (12)−0.0271 (12)−0.0068 (14)−0.0219 (14)
F10.166 (4)0.136 (3)0.159 (4)−0.059 (3)−0.010 (4)−0.044 (4)
F20.170 (4)0.120 (3)0.148 (4)−0.072 (3)−0.012 (4)−0.026 (4)
F30.077 (3)0.234 (5)0.116 (3)−0.002 (3)−0.004 (3)0.021 (4)
F40.117 (4)0.264 (7)0.073 (3)0.014 (4)0.002 (3)−0.007 (4)
F50.135 (5)0.198 (6)0.087 (4)−0.029 (4)0.016 (3)0.012 (3)
F60.067 (3)0.206 (5)0.170 (4)0.001 (3)−0.014 (4)−0.073 (4)
P20.0872 (16)0.1174 (17)0.0929 (15)−0.0272 (13)−0.0190 (16)0.0416 (15)
F70.130 (5)0.235 (6)0.171 (5)−0.026 (4)0.038 (5)−0.041 (6)
F80.375 (14)0.489 (14)0.201 (8)−0.219 (11)−0.182 (9)0.238 (9)
F90.263 (8)0.293 (8)0.104 (5)−0.080 (7)−0.052 (5)0.083 (5)
F100.206 (7)0.153 (5)0.355 (12)−0.041 (5)0.034 (7)0.001 (7)
F110.70 (2)0.233 (7)0.241 (9)−0.308 (11)0.025 (13)−0.029 (8)
F120.111 (5)0.491 (15)0.340 (14)0.080 (7)−0.002 (6)0.009 (12)

Geometric parameters (Å, °)

O1—C81.406 (6)C6—C71.518 (7)
O1—H1A0.8200C6—C91.556 (8)
N1—C41.219 (9)C7—H7A0.9700
N1—C11.413 (9)C7—H7B0.9700
N1—C21.482 (10)C8—H8A0.9700
C1—H1B0.9600C8—H8B0.9700
C1—H1C0.9600C9—H9A0.9700
C1—H1D0.9600C9—H9B0.9700
O2—C71.428 (7)C10—C111.336 (8)
O2—H2A0.8200C10—H10A0.9300
N2—C21.314 (8)C11—H11A0.9300
N2—C31.354 (9)C12—H12A0.9300
N2—C51.434 (6)C13—H13A0.9600
C2—H2B0.9300C13—H13B0.9600
N3—C121.338 (6)C13—H13C0.9600
N3—C101.372 (7)P1—F21.538 (4)
N3—C91.467 (7)P1—F61.570 (4)
C3—C41.419 (11)P1—F41.572 (4)
C3—H3A0.9300P1—F31.578 (4)
N4—C121.335 (7)P1—F51.586 (5)
N4—C111.363 (8)P1—F11.598 (4)
N4—C131.454 (7)P2—F111.390 (6)
C4—H4A0.9300P2—F81.429 (6)
C5—C61.519 (6)P2—F121.489 (7)
C5—H5A0.9700P2—F91.503 (5)
C5—H5B0.9700P2—F71.521 (6)
C6—C81.506 (6)P2—F101.628 (6)
C8—O1—H1A109.5H8A—C8—H8B108.3
C4—N1—C1124.8 (9)N3—C9—C6115.2 (4)
C4—N1—C2117.1 (8)N3—C9—H9A108.5
C1—N1—C2118.0 (8)C6—C9—H9A108.5
N1—C1—H1B109.5N3—C9—H9B108.5
N1—C1—H1C109.5C6—C9—H9B108.5
H1B—C1—H1C109.5H9A—C9—H9B107.5
N1—C1—H1D109.5C11—C10—N3108.5 (6)
H1B—C1—H1D109.5C11—C10—H10A125.8
H1C—C1—H1D109.5N3—C10—H10A125.8
C7—O2—H2A109.5C10—C11—N4106.1 (6)
C2—N2—C3111.6 (7)C10—C11—H11A126.9
C2—N2—C5124.9 (6)N4—C11—H11A126.9
C3—N2—C5122.9 (7)N4—C12—N3107.3 (5)
N2—C2—N199.3 (7)N4—C12—H12A126.4
N2—C2—H2B130.3N3—C12—H12A126.4
N1—C2—H2B130.3N4—C13—H13A109.5
C12—N3—C10107.8 (5)N4—C13—H13B109.5
C12—N3—C9123.4 (5)H13A—C13—H13B109.5
C10—N3—C9128.2 (5)N4—C13—H13C109.5
N2—C3—C4109.2 (8)H13A—C13—H13C109.5
N2—C3—H3A125.4H13B—C13—H13C109.5
C4—C3—H3A125.4F2—P1—F691.8 (3)
C12—N4—C11109.9 (6)F2—P1—F493.7 (3)
C12—N4—C13129.4 (6)F6—P1—F488.3 (3)
C11—N4—C13120.7 (6)F2—P1—F388.6 (3)
N1—C4—C3102.7 (9)F6—P1—F3178.7 (4)
N1—C4—H4A128.7F4—P1—F392.9 (3)
C3—C4—H4A128.7F2—P1—F588.0 (3)
N2—C5—C6112.6 (4)F6—P1—F590.6 (3)
N2—C5—H5A109.1F4—P1—F5178.0 (3)
C6—C5—H5A109.1F3—P1—F588.1 (3)
N2—C5—H5B109.1F2—P1—F1175.5 (4)
C6—C5—H5B109.1F6—P1—F187.8 (3)
H5A—C5—H5B107.8F4—P1—F190.8 (3)
C8—C6—C7108.5 (4)F3—P1—F191.7 (3)
C8—C6—C5114.9 (4)F5—P1—F187.5 (3)
C7—C6—C5112.5 (4)F11—P2—F895.0 (6)
C8—C6—C9110.3 (4)F11—P2—F1284.9 (6)
C7—C6—C9109.2 (4)F8—P2—F1290.2 (6)
C5—C6—C9101.1 (4)F11—P2—F989.6 (5)
O2—C7—C6110.6 (4)F8—P2—F9174.9 (6)
O2—C7—H7A109.5F12—P2—F988.0 (5)
C6—C7—H7A109.5F11—P2—F7104.1 (7)
O2—C7—H7B109.5F8—P2—F792.1 (5)
C6—C7—H7B109.5F12—P2—F7170.5 (5)
H7A—C7—H7B108.1F9—P2—F788.9 (4)
O1—C8—C6109.0 (4)F11—P2—F10169.1 (6)
O1—C8—H8A109.9F8—P2—F1090.5 (5)
C6—C8—H8A109.9F12—P2—F1085.6 (5)
O1—C8—H8B109.9F9—P2—F1084.6 (4)
C6—C8—H8B109.9F7—P2—F1085.1 (3)
C3—N2—C2—N11.7 (7)C7—C6—C8—O1−175.8 (5)
C5—N2—C2—N1173.0 (5)C5—C6—C8—O157.2 (7)
C4—N1—C2—N2−1.5 (9)C9—C6—C8—O1−56.3 (6)
C1—N1—C2—N2−178.1 (6)C12—N3—C9—C693.2 (6)
C2—N2—C3—C4−1.6 (9)C10—N3—C9—C6−96.3 (7)
C5—N2—C3—C4−173.1 (6)C8—C6—C9—N3−66.1 (6)
C1—N1—C4—C3177.0 (7)C7—C6—C9—N353.0 (6)
C2—N1—C4—C30.6 (10)C5—C6—C9—N3171.8 (5)
N2—C3—C4—N10.5 (9)C12—N3—C10—C11−6.0 (7)
C2—N2—C5—C695.0 (7)C9—N3—C10—C11−177.7 (6)
C3—N2—C5—C6−94.7 (7)N3—C10—C11—N44.7 (8)
N2—C5—C6—C868.1 (6)C12—N4—C11—C10−1.8 (8)
N2—C5—C6—C7−56.8 (6)C13—N4—C11—C10176.3 (6)
N2—C5—C6—C9−173.2 (5)C11—N4—C12—N3−1.8 (7)
C8—C6—C7—O2178.5 (5)C13—N4—C12—N3−179.7 (6)
C5—C6—C7—O2−53.2 (6)C10—N3—C12—N44.7 (7)
C9—C6—C7—O258.2 (6)C9—N3—C12—N4176.9 (5)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C5—H5B···O10.972.562.910 (7)101
C9—H9A···O10.972.462.831 (8)102
O1—H1A···F100.822.323.001 (8)141
O2—H2A···O1i0.821.972.787 (6)175
C2—H2B···F7i0.932.413.261 (11)152
C13—H13B···O2ii0.962.543.186 (7)125

Symmetry codes: (i) −x+2, −y+1, z+1/2; (ii) x−1/2, −y+1/2, z.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RK2245).

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