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Acta Crystallogr Sect E Struct Rep Online. 2008 December 1; 64(Pt 12): o2480.
Published online 2008 November 29. doi:  10.1107/S160053680803746X
PMCID: PMC2960103

3,3′-Dimethyl-1,1′-(propane-1,3-di­yl)diimidazol-1-ium bis(hexafluoro­phosphate)

Abstract

In the title compound, C11H18N4 2+·2PF6 , the dihedral angle between the two planar imidozlium rings is 6.1 (2)°. Both [PF6] anions are disordered [occupancies 0.65 (2):0.35 (2) and 0.59 (5):0.41 (5)]. The crystal packing is stabilized by inter­molecular C—H(...)F hydrogen bonds which link two mol­ecules, forming centrosymmetric dimers.

Related literature

For applications of dicationic ionic liquids, see: Jared et al. (2005 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]); Matsumoto & Hagiwara (2007 [triangle]).

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Object name is e-64-o2480-scheme1.jpg

Experimental

Crystal data

  • C11H18N4 2+·2PF6
  • M r = 496.23
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o2480-efi1.jpg
  • a = 8.2300 (16) Å
  • b = 10.192 (2) Å
  • c = 12.856 (3) Å
  • α = 107.99 (3)°
  • β = 104.50 (3)°
  • γ = 96.35 (3)°
  • V = 972.1 (5) Å3
  • Z = 2
  • Mo Kα radiation
  • μ = 0.34 mm−1
  • T = 298 (2) K
  • 0.30 × 0.30 × 0.20 mm

Data collection

  • Enraf–Nonius CAD-4 diffractometer
  • Absorption correction: ψ scan (North et al., 1968 [triangle]) T min = 0.905, T max = 0.935
  • 3484 measured reflections
  • 3484 independent reflections
  • 2637 reflections with I > 2σ(I)
  • 3 standard reflections every 200 reflections intensity decay: none

Refinement

  • R[F 2 > 2σ(F 2)] = 0.065
  • wR(F 2) = 0.179
  • S = 0.97
  • 3484 reflections
  • 372 parameters
  • H-atom parameters constrained
  • Δρmax = 0.30 e Å−3
  • Δρmin = −0.48 e Å−3

Data collection: CAD-4 Software (Enraf–Nonius, 1989 [triangle]); cell refinement: CAD-4 Software; 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 I, global, x1. DOI: 10.1107/S160053680803746X/rn2047sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S160053680803746X/rn2047Isup2.hkl

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

Acknowledgments

The authors thank Professor Hua-Qin Wang of the Analysis Centre, Nanjing University, for carrying out the X-ray crystallographic analysis.

supplementary crystallographic information

Comment

The title compound is a dicationic ionic liquid, which has high thermal stability. Applications of the dicationic ionic liquid are found in biochemistry as well as many areas of chemistry (Jared et al., 2005). We report the crystal structure of the title compound, (I).

In (I) (Fig. 1), the bond lengths and angles are within normal ranges (Allen et al., 1987). Rings A (C1—C5/N1/N2) and B (C7—C11/N3/N4) are, of course, planar and the dihedral angle between them is 6.1 (2) °. In the crystal structure, intermolecular C-H···F hydrogen bonds (Table 1) link the molecules (Fig. 2), forming centrosymmetric dimers, which may be effective in the stabilization of the crystals.

Experimental

1,3-Dibromide propane(10.1 g, 0.05 mol) was added to acetonitrile solution(50 ml) of dehydrate imidazole(9.4 g, 0.11 mol) at 353 K. After stirring for 24 h, the mixture was cooled to room temperature and filtered. The solids were washed with ethyl acetate and dried. Above solid(1.42 g, 5 mmol) was dissolved in distilled water(50 mL) and potassium hexafluorophosphate(1.84 g, 10 mmol) was added. After stirring at room temperature for 3 h, a white solid formed which was collected by filtration, washed with distilled water(20 mL) and dried; The product was purified by repeated crystallization. Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of acetone. Each starting material was distilled in advance under reduced pressure with 5 Å molecular sieve. (yield; 0.848 g, 40 %, m.p. 414 K)

Refinement

Both two distinct hexafluorophosphate groups are disordered over two sites while central P atoms are fixed; the site occupancy factors were refined and converged to 0.65 (2) and 0.35 (2) for F1—F6 and F1'—F6', 0.41 (5) and 0.59 (5) for F7—F12 and F7'—F12' respectively.

H atoms were positioned geometrically, with C—H = 0.93, 0.96 and 0.97 Å for methine, methyl, methylene H, respectively, 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 all other H atoms.

Figures

Fig. 1.
The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50 % probability level. Dashed lines indicate C-H···F hydrogen bonds.
Fig. 2.
Crystal packing in (I). Dashed lines indicate intermolecular C-H···F hydrogen bonds.

Crystal data

C11H18N42+·2PF6Z = 2
Mr = 496.23F000 = 500
Triclinic, P1Dx = 1.695 Mg m3
Hall symbol: -P 1Melting point: 414 K
a = 8.2300 (16) ÅMo Kα radiation λ = 0.71073 Å
b = 10.192 (2) ÅCell parameters from 25 reflections
c = 12.856 (3) Åθ = 10–12º
α = 107.99 (3)ºµ = 0.34 mm1
β = 104.50 (3)ºT = 298 (2) K
γ = 96.35 (3)ºBlock, colorless
V = 972.1 (5) Å30.30 × 0.30 × 0.20 mm

Data collection

Enraf–Nonius CAD-4 diffractometerRint = 0.000
Radiation source: fine-focus sealed tubeθmax = 25.2º
Monochromator: graphiteθmin = 1.8º
T = 298(2) Kh = −9→9
ω/2θ scansk = −12→11
Absorption correction: ψ scan(North et al., 1968)l = 0→15
Tmin = 0.905, Tmax = 0.9353 standard reflections
3484 measured reflections every 200 reflections
3484 independent reflections intensity decay: none
2637 reflections with I > 2σ(I)

Refinement

Refinement on F2Secondary atom site location: difference Fourier map
Least-squares matrix: fullHydrogen site location: inferred from neighbouring sites
R[F2 > 2σ(F2)] = 0.065H-atom parameters constrained
wR(F2) = 0.180  w = 1/[σ2(Fo2) + (0.1017P)2 + 1.1631P] where P = (Fo2 + 2Fc2)/3
S = 0.97(Δ/σ)max = 0.008
3484 reflectionsΔρmax = 0.30 e Å3
372 parametersΔρmin = −0.48 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

Special details

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)

xyzUiso*/UeqOcc. (<1)
P10.17011 (11)0.74314 (10)0.95610 (8)0.0542 (3)
F10.2940 (19)0.681 (2)1.0328 (16)0.131 (5)0.65 (2)
F20.0282 (10)0.752 (2)0.8566 (8)0.109 (4)0.65 (2)
F30.2002 (14)0.6372 (10)0.8485 (8)0.108 (4)0.65 (2)
F40.114 (3)0.871 (3)1.042 (3)0.104 (9)0.35 (2)
F50.0358 (18)0.6358 (16)0.9717 (13)0.105 (4)0.65 (2)
F60.3276 (19)0.8550 (14)0.9610 (14)0.089 (4)0.65 (2)
F1'0.309 (3)0.753 (3)1.0618 (19)0.116 (7)0.35 (2)
F2'0.072 (3)0.838 (3)0.894 (2)0.107 (6)0.35 (2)
F3'0.229 (3)0.618 (2)0.880 (3)0.154 (13)0.35 (2)
F4'0.143 (2)0.8495 (18)1.0606 (13)0.115 (5)0.65 (2)
F5'0.004 (3)0.643 (3)0.937 (3)0.151 (12)0.35 (2)
F6'0.298 (4)0.843 (3)0.936 (2)0.097 (8)0.35 (2)
P20.71510 (11)0.77369 (9)0.42397 (8)0.0508 (3)
F70.863 (3)0.772 (3)0.536 (2)0.073 (5)0.41 (5)
F80.671 (5)0.902 (2)0.513 (3)0.119 (8)0.41 (5)
F90.573 (4)0.776 (5)0.328 (3)0.135 (11)0.41 (5)
F100.803 (4)0.865 (3)0.380 (3)0.070 (4)0.41 (5)
F110.765 (3)0.6468 (16)0.3366 (17)0.084 (5)0.41 (5)
F120.588 (3)0.659 (2)0.4499 (13)0.039 (4)0.41 (5)
F8'0.633 (2)0.8923 (15)0.4897 (19)0.088 (4)0.59 (5)
F9'0.561 (2)0.747 (2)0.3081 (16)0.080 (4)0.59 (5)
F7'0.864 (3)0.800 (4)0.526 (2)0.127 (8)0.59 (5)
F11'0.791 (2)0.6508 (15)0.359 (2)0.093 (4)0.59 (5)
F10'0.849 (3)0.891 (2)0.402 (2)0.075 (3)0.59 (5)
F12'0.602 (3)0.673 (2)0.4581 (16)0.083 (6)0.59 (5)
N10.6733 (4)0.7139 (4)0.9682 (3)0.0524 (8)
C10.7252 (7)0.7372 (7)1.0910 (4)0.0879 (17)
H1A0.76860.83591.13360.132*
H1B0.81320.68581.10810.132*
H1C0.62810.70521.11190.132*
N20.6251 (4)0.7563 (3)0.8105 (2)0.0432 (7)
C20.6823 (4)0.8143 (4)0.9236 (3)0.0452 (8)
H2A0.72240.91010.96500.054*
N30.2487 (4)0.7375 (3)0.5612 (3)0.0450 (7)
C30.5781 (5)0.6144 (4)0.7827 (4)0.0597 (11)
H3A0.53350.54780.70910.072*
N40.1799 (4)0.6783 (3)0.3781 (3)0.0458 (7)
C40.6078 (5)0.5889 (4)0.8803 (4)0.0645 (12)
H4A0.58740.50080.88730.077*
C50.6155 (6)0.8329 (5)0.7305 (4)0.0671 (12)
H5A0.59760.76650.65400.081*
H5B0.72370.89800.75230.081*
C60.4733 (7)0.9135 (5)0.7285 (4)0.0737 (14)
H6A0.48980.97640.80600.088*
H6B0.48300.97150.68220.088*
C70.2951 (6)0.8265 (5)0.6833 (4)0.0699 (13)
H7A0.28480.76660.72810.084*
H7B0.21470.88860.69310.084*
C80.2296 (4)0.7848 (4)0.4749 (3)0.0440 (8)
H8A0.24860.87930.48190.053*
C90.1662 (5)0.5574 (4)0.4025 (4)0.0606 (11)
H9A0.13370.46600.34950.073*
C100.2074 (5)0.5934 (4)0.5150 (4)0.0609 (11)
H10A0.20820.53200.55560.073*
C110.1433 (6)0.6887 (6)0.2638 (4)0.0789 (14)
H11A0.16230.78620.27090.118*
H11B0.02610.64470.22090.118*
H11C0.21760.64220.22470.118*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
P10.0474 (5)0.0577 (6)0.0566 (6)0.0048 (4)0.0160 (4)0.0139 (4)
F10.124 (8)0.185 (12)0.171 (12)0.084 (8)0.069 (8)0.146 (11)
F20.081 (4)0.157 (10)0.082 (5)0.029 (6)0.005 (3)0.047 (6)
F30.141 (7)0.077 (5)0.081 (5)−0.021 (5)0.066 (4)−0.019 (3)
F40.098 (10)0.049 (6)0.17 (2)0.013 (6)0.100 (12)−0.003 (9)
F50.107 (9)0.090 (6)0.131 (6)−0.011 (5)0.063 (6)0.047 (5)
F60.068 (4)0.059 (4)0.130 (10)−0.007 (3)0.047 (5)0.013 (5)
F1'0.073 (7)0.159 (18)0.093 (8)0.019 (11)−0.019 (7)0.050 (12)
F2'0.091 (11)0.111 (12)0.139 (15)0.061 (10)0.019 (10)0.070 (11)
F3'0.174 (16)0.104 (11)0.12 (3)−0.081 (12)0.09 (2)−0.047 (15)
F4'0.174 (11)0.088 (8)0.079 (5)0.007 (6)0.077 (6)0.000 (5)
F5'0.060 (7)0.090 (13)0.24 (3)−0.031 (7)0.080 (13)−0.039 (14)
F6'0.131 (18)0.096 (11)0.057 (7)−0.035 (9)0.054 (9)0.017 (6)
P20.0517 (5)0.0472 (5)0.0584 (6)0.0079 (4)0.0169 (4)0.0189 (4)
F70.055 (6)0.096 (8)0.063 (7)0.011 (5)−0.004 (5)0.040 (7)
F80.23 (2)0.039 (6)0.108 (10)−0.009 (9)0.120 (12)0.005 (6)
F90.093 (12)0.21 (3)0.128 (19)0.047 (15)0.005 (11)0.12 (2)
F100.063 (10)0.053 (10)0.089 (9)−0.027 (6)0.026 (8)0.027 (8)
F110.129 (11)0.052 (7)0.060 (7)−0.011 (8)0.058 (6)−0.008 (6)
F120.049 (6)0.027 (5)0.041 (6)−0.003 (4)0.021 (4)0.011 (4)
F8'0.109 (7)0.042 (5)0.144 (11)0.041 (5)0.087 (6)0.029 (6)
F9'0.059 (5)0.120 (7)0.059 (5)0.015 (4)0.008 (3)0.036 (5)
F7'0.081 (7)0.191 (17)0.104 (8)−0.001 (9)−0.013 (5)0.084 (9)
F11'0.098 (6)0.084 (7)0.157 (12)0.063 (6)0.096 (7)0.063 (8)
F10'0.068 (8)0.046 (6)0.103 (9)−0.028 (5)0.044 (7)0.017 (5)
F12'0.085 (9)0.066 (9)0.110 (10)0.005 (6)0.055 (8)0.032 (7)
N10.0406 (17)0.073 (2)0.0564 (19)0.0199 (15)0.0175 (15)0.0355 (18)
C10.074 (3)0.144 (5)0.075 (3)0.039 (3)0.024 (3)0.072 (4)
N20.0390 (15)0.0474 (17)0.0381 (15)0.0049 (12)0.0096 (12)0.0108 (13)
C20.0433 (19)0.047 (2)0.0394 (19)0.0078 (15)0.0073 (15)0.0113 (16)
N30.0434 (16)0.0528 (18)0.0523 (18)0.0164 (13)0.0173 (14)0.0321 (15)
C30.052 (2)0.046 (2)0.065 (3)0.0067 (17)0.013 (2)0.0041 (19)
N40.0344 (15)0.0536 (18)0.0444 (17)0.0071 (13)0.0079 (12)0.0139 (14)
C40.050 (2)0.050 (2)0.101 (4)0.0120 (18)0.024 (2)0.033 (2)
C50.065 (3)0.085 (3)0.047 (2)−0.006 (2)0.010 (2)0.030 (2)
C60.111 (4)0.059 (3)0.039 (2)0.019 (3)0.002 (2)0.0170 (19)
C70.081 (3)0.097 (4)0.050 (2)0.047 (3)0.026 (2)0.035 (2)
C80.0453 (19)0.0414 (19)0.051 (2)0.0084 (15)0.0115 (16)0.0261 (17)
C90.044 (2)0.037 (2)0.089 (3)0.0003 (16)0.012 (2)0.014 (2)
C100.048 (2)0.054 (2)0.094 (3)0.0080 (18)0.018 (2)0.049 (2)
C110.068 (3)0.108 (4)0.053 (3)0.020 (3)0.009 (2)0.024 (3)

Geometric parameters (Å, °)

P1—F21.536 (8)C1—H1C0.9600
P1—F5'1.534 (19)N2—C21.322 (4)
P1—F4'1.528 (12)N2—C31.362 (5)
P1—F6'1.51 (2)N2—C51.465 (5)
P1—F11.563 (10)C2—H2A0.9300
P1—F1'1.509 (18)N3—C81.322 (4)
P1—F3'1.556 (16)N3—C101.369 (5)
P1—F51.561 (11)N3—C71.475 (5)
P1—F31.565 (7)C3—C41.328 (6)
P1—F2'1.601 (12)C3—H3A0.9300
P1—F61.603 (14)N4—C81.307 (5)
P1—F41.62 (2)N4—C91.362 (5)
F1'—F4'1.77 (3)N4—C111.463 (5)
P2—F11'1.565 (10)C4—H4A0.9300
P2—F7'1.48 (2)C5—C61.501 (7)
P2—F12'1.54 (2)C5—H5A0.9700
P2—F91.48 (3)C5—H5B0.9700
P2—F71.65 (3)C6—C71.497 (7)
P2—F101.44 (3)C6—H6A0.9700
P2—F8'1.572 (9)C6—H6B0.9700
P2—F10'1.674 (19)C7—H7A0.9700
P2—F81.596 (18)C7—H7B0.9700
P2—F121.65 (2)C8—H8A0.9300
P2—F111.597 (13)C9—C101.319 (6)
P2—F9'1.62 (2)C9—H9A0.9300
N1—C21.323 (5)C10—H10A0.9300
N1—C41.358 (6)C11—H11A0.9600
N1—C11.463 (5)C11—H11B0.9600
C1—H1A0.9600C11—H11C0.9600
C1—H1B0.9600
F2—P1—F5'70.4 (13)F10'—P2—F9'95.3 (12)
F5'—P1—F4'90.8 (12)C2—N1—C4107.8 (3)
F5'—P1—F6'160 (2)C2—N1—C1124.8 (4)
F4'—P1—F6'97.2 (11)C4—N1—C1127.3 (4)
F2—P1—F1160.9 (14)N1—C1—H1A109.5
F5'—P1—F1'112 (2)N1—C1—H1B109.5
F4'—P1—F1'71.3 (12)H1A—C1—H1B109.5
F6'—P1—F1'87.2 (14)N1—C1—H1C109.5
F5'—P1—F3'89.3 (13)H1A—C1—H1C109.5
F4'—P1—F3'161.5 (16)H1B—C1—H1C109.5
F6'—P1—F3'88.8 (14)C2—N2—C3108.1 (3)
F1'—P1—F3'91.6 (14)C2—N2—C5125.3 (3)
F2—P1—F588.4 (7)C3—N2—C5126.6 (3)
F1—P1—F580.4 (9)N1—C2—N2108.9 (3)
F2—P1—F377.4 (8)N1—C2—H2A125.6
F1—P1—F388.5 (7)N2—C2—H2A125.6
F5—P1—F396.3 (7)C8—N3—C10107.2 (3)
F5'—P1—F2'93.1 (12)C8—N3—C7125.2 (3)
F4'—P1—F2'81.4 (13)C10—N3—C7127.5 (3)
F6'—P1—F2'70.4 (15)C4—C3—N2107.2 (4)
F1'—P1—F2'142 (2)C4—C3—H3A126.4
F3'—P1—F2'117 (2)N2—C3—H3A126.4
F2—P1—F6101.0 (9)C8—N4—C9108.1 (3)
F1—P1—F691.1 (7)C8—N4—C11125.4 (4)
F5—P1—F6170.3 (9)C9—N4—C11126.5 (4)
F3—P1—F688.2 (6)C3—C4—N1108.0 (4)
F2—P1—F488.3 (15)C3—C4—H4A126.0
F1—P1—F4106.7 (12)N1—C4—H4A126.0
F5—P1—F489.2 (10)N2—C5—C6112.3 (4)
F3—P1—F4164.5 (13)N2—C5—H5A109.2
F6—P1—F488.6 (9)C6—C5—H5A109.2
P1—F1'—F4'54.9 (9)N2—C5—H5B109.1
P1—F4'—F1'53.8 (8)C6—C5—H5B109.1
F11'—P2—F7'87.0 (11)H5A—C5—H5B107.9
F11'—P2—F12'92.0 (9)C7—C6—C5115.9 (4)
F7'—P2—F12'93.3 (13)C7—C6—H6A108.3
F9—P2—F7175.4 (16)C5—C6—H6A108.3
F9—P2—F1079 (2)C7—C6—H6B108.3
F7—P2—F10104.1 (17)C5—C6—H6B108.3
F11'—P2—F8'177.5 (8)H6A—C6—H6B107.4
F7'—P2—F8'93.5 (11)N3—C7—C6113.1 (4)
F12'—P2—F8'85.5 (9)N3—C7—H7A109.0
F11'—P2—F10'90.5 (10)C6—C7—H7A109.0
F7'—P2—F10'81.4 (19)N3—C7—H7B109.0
F12'—P2—F10'174.0 (13)C6—C7—H7B109.0
F8'—P2—F10'92.0 (10)H7A—C7—H7B107.8
F9—P2—F891.7 (16)N4—C8—N3109.4 (3)
F7—P2—F885.2 (16)N4—C8—H8A125.3
F10—P2—F892.9 (14)N3—C8—H8A125.3
F9—P2—F1290.7 (15)C10—C9—N4107.6 (4)
F7—P2—F1286.0 (11)C10—C9—H9A126.2
F10—P2—F12169.4 (14)N4—C9—H9A126.2
F8—P2—F1291.3 (10)C9—C10—N3107.6 (3)
F9—P2—F1189.6 (16)C9—C10—H10A126.2
F7—P2—F1193.5 (12)N3—C10—H10A126.2
F10—P2—F1186.4 (15)N4—C11—H11A109.5
F8—P2—F11178.3 (13)N4—C11—H11B109.5
F12—P2—F1189.8 (9)H11A—C11—H11B109.5
F11'—P2—F9'91.1 (10)N4—C11—H11C109.5
F7'—P2—F9'176.2 (13)H11A—C11—H11C109.5
F12'—P2—F9'90.1 (10)H11B—C11—H11C109.5
F8'—P2—F9'88.5 (10)

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C2—H2A···F6i0.932.413.256 (16)151
C7—H7A···F30.972.493.446 (12)167

Symmetry codes: (i) −x+1, −y+2, −z+2.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: RN2047).

References

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