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

Jin-hua Liang; Su-lan Dong; Hui Cang; Jin-tang Wang

doi:10.1107/S160053680803746X

. 2008 Nov 29;64(Pt 12):o2480. doi: 10.1107/S160053680803746X

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

Jin-hua Liang ^a, Su-lan Dong ^a,^b, Hui Cang ^a, Jin-tang Wang ^a,^*

PMCID: PMC2960103 PMID: 21581445

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 ▶). For bond-length data, see: Allen et al. (1987 ▶); Matsumoto & Hagiwara (2007 ▶).

Experimental

Crystal data

C₁₁H₁₈N₄ ²⁺·2PF₆ ⁻
M _r = 496.23
Triclinic,
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 ▶) 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
Δρ_max = 0.30 e Å⁻³
Δρ_min = −0.48 e Å⁻³

Data collection: CAD-4 Software (Enraf–Nonius, 1989 ▶); cell refinement: CAD-4 Software; 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.

Supplementary Material

Crystal structure: contains datablocks I, global, x1. DOI: 10.1107/S160053680803746X/rn2047sup1.cif

e-64-o2480-sup1.cif^{(21.5KB, cif)}

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

e-64-o2480-Isup2.hkl^{(170.8KB, hkl)}

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

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
C2—H2A⋯F6ⁱ	0.93	2.41	3.256 (16)	151
C7—H7A⋯F3	0.97	2.49	3.446 (12)	167

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Symmetry code: (i) Inline graphic .

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)