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Acta Crystallogr Sect E Struct Rep Online. 2008 December 1; 64(Pt 12): o2495.
Published online 2008 November 29. doi:  10.1107/S1600536808039639
PMCID: PMC2959814

1,1′-(Hexane-1,6-di­yl)dipyridinium bis­(hexa­fluoro­phosphate)

Abstract

The asymmetric unit of the title compound, C16H22N2 2+·2PF6 , contains one half-mol­ecule and a hexa­fluoro­phosphate anion. In the crystal structure, inter­molecular C—H(...)F hydrogen bonds link the mol­ecules. The F atoms in the hexa­fluoro­phosphate anion are disordered over two positions and were refined with occupancies of 0.43 (2) and 0.57 (2).

Related literature

For general background, see: Jared et al. (2005 [triangle]). For bond-length data, see: Allen et al. (1987 [triangle]).

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Object name is e-64-o2495-scheme1.jpg

Experimental

Crystal data

  • C16H22N2 2+·2PF6
  • M r = 532.30 (3)
  • Triclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-o2495-efi1.jpg
  • a = 7.9140 (16) Å
  • b = 9.2930 (18) Å
  • c = 9.4870 (19) Å
  • α = 65.13 (3)°
  • β = 65.46 (3)°
  • γ = 74.37 (3)°
  • V = 572.0 (3) Å3
  • Z = 1
  • Mo Kα radiation
  • μ = 0.29 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 = 0.917, T max = 0.944
  • 2172 measured reflections
  • 2014 independent reflections
  • 1499 reflections with I > 2σ(I)
  • R int = 0.047
  • 3 standard reflections frequency: 120 min intensity decay: none

Refinement

  • R[F 2 > 2σ(F 2)] = 0.065
  • wR(F 2) = 0.166
  • S = 1.00
  • 2014 reflections
  • 200 parameters
  • H-atom parameters constrained
  • Δρmax = 0.30 e Å−3
  • Δρmin = −0.38 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/S1600536808039639/hk2581sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808039639/hk2581Isup2.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 herein the crystal structure of the title compound.

The asymmetric unit of the title compound (Fig. 1) contains one-half molecule and a hexafluorophosphate molecule, where the bond lengths (Allen et al., 1987) and angles are within normal ranges.

In the crystal structure, intermolecular C-H···F hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental

For the preparation of the title compound, 1,6-dibromide hexane (12.2 g, 0.05 mol) was added to acetonitrile solution (50 ml) of dehydrate pyridine (7.91 g, 0.10 mol) at 353 K. After stirring for 24 h, the mixture was cooled to room temperature and filtered. The solid was washed with ethyl acetate and dried. Then, the solid (2.01 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, the colorless solid formed was collected by filtration, washed with distilled water (50 ml) and dried. The product was purified by repeated crystallization. Crystals suitable for X-ray analysis were obtained by slow evaporation of acetone (yield; 3.08 g, 80%, m.p. 513 K).

Refinement

The F1, F2, F3, F4, F5 and F6 atoms in hexafluorophosphate were disordered over two positions. During the refinement process the disordered atoms were refined with occupancies of 0.43 (2) for F1, F2, F3, F4, F5 , F6 and 0.57 (2) for F1', F2', F3', F4', F5', F6', respectively. H atoms were positioned geometrically, with C-H = 0.93 and 0.97 Å for aromatic and methylene H, respectively, and constrained to ride on their parent atoms with Uiso(H) = 1.2Ueq(C).

Figures

Fig. 1.
The asymmetric unit of the title compound, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.
Fig. 2.
A partial packing diagram of the title compound. Hydrogen bonds are shown as dashed lines.

Crystal data

C16H22N22+·2P1F6Z = 1
Mr = 532.30 (3)F000 = 270
Triclinic, P1Dx = 1.545 Mg m3
Hall symbol: -P 1Melting point: 513 K
a = 7.9140 (16) ÅMo Kα radiation λ = 0.71073 Å
b = 9.2930 (18) ÅCell parameters from 25 reflections
c = 9.4870 (19) Åθ = 10–12º
α = 65.13 (3)ºµ = 0.29 mm1
β = 65.46 (3)ºT = 298 (2) K
γ = 74.37 (3)ºBlock, colorless
V = 572.0 (3) Å30.30 × 0.30 × 0.20 mm

Data collection

Enraf–Nonius CAD-4 diffractometerRint = 0.047
Radiation source: fine-focus sealed tubeθmax = 25.1º
Monochromator: graphiteθmin = 2.4º
T = 298(2) Kh = −8→9
ω/2θ scansk = −9→10
Absorption correction: ψ scan(North et al., 1968)l = 0→11
Tmin = 0.917, Tmax = 0.9443 standard reflections
2172 measured reflections every 120 min
2014 independent reflections intensity decay: none
1499 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) = 0.166  w = 1/[σ2(Fo2) + (0.06P)2 + 0.95P] where P = (Fo2 + 2Fc2)/3
S = 1.01(Δ/σ)max < 0.001
2014 reflectionsΔρmax = 0.30 e Å3
200 parametersΔρmin = −0.38 e Å3
Primary atom site location: structure-invariant direct methodsExtinction correction: none

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.
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)
P0.16995 (14)0.79005 (13)0.78487 (13)0.0539 (4)
N0.6355 (4)0.7536 (4)0.2462 (4)0.0472 (8)
F1−0.006 (3)0.696 (3)0.842 (2)0.156 (6)0.43 (2)
F20.369 (2)0.8457 (19)0.721 (2)0.104 (5)0.43 (2)
F30.034 (2)0.8894 (16)0.8982 (15)0.091 (4)0.43 (2)
F40.215 (2)0.645 (2)0.939 (2)0.076 (4)0.43 (2)
F50.126 (2)0.936 (2)0.635 (2)0.078 (4)0.43 (2)
F60.223 (3)0.677 (3)0.684 (2)0.076 (4)0.43 (2)
F1'−0.0338 (9)0.7809 (16)0.8155 (14)0.118 (4)0.57 (2)
F2'0.375 (2)0.785 (2)0.775 (2)0.144 (5)0.57 (2)
F3'0.127 (2)0.9036 (12)0.8910 (13)0.098 (3)0.57 (2)
F4'0.150 (2)0.6338 (18)0.9501 (17)0.090 (4)0.57 (2)
F5'0.195 (2)0.9495 (17)0.6211 (17)0.094 (4)0.57 (2)
F6'0.2820 (19)0.6854 (19)0.6687 (18)0.082 (4)0.57 (2)
C10.6255 (6)0.6893 (5)0.1468 (5)0.0607 (11)
H1A0.72270.61590.11130.073*
C20.4732 (7)0.7312 (6)0.0972 (6)0.0735 (13)
H2A0.46610.68660.02880.088*
C30.3292 (6)0.8420 (6)0.1517 (6)0.0751 (14)
H3A0.22600.87360.11790.090*
C40.3402 (6)0.9030 (6)0.2537 (6)0.0721 (13)
H4A0.24280.97510.29130.087*
C50.4934 (5)0.8603 (5)0.3029 (5)0.0543 (10)
H5A0.50030.90290.37300.065*
C60.7977 (5)0.7070 (5)0.3014 (5)0.0580 (10)
H6A0.83870.80220.28960.070*
H6B0.89980.65580.23070.070*
C70.7536 (5)0.5942 (5)0.4801 (5)0.0563 (10)
H7A0.71840.49690.49080.068*
H7B0.64750.64340.55020.068*
C80.9189 (5)0.5519 (5)0.5406 (5)0.0602 (11)
H8A0.96280.64980.51830.072*
H8B0.87610.49630.65950.072*

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
P0.0470 (6)0.0550 (6)0.0538 (6)0.0051 (4)−0.0114 (5)−0.0263 (5)
N0.0332 (15)0.0466 (17)0.0475 (17)−0.0002 (13)−0.0093 (13)−0.0107 (14)
F10.136 (9)0.160 (11)0.165 (9)−0.050 (8)−0.033 (7)−0.049 (8)
F20.082 (6)0.104 (7)0.133 (9)−0.045 (5)−0.035 (6)−0.030 (6)
F30.101 (8)0.077 (5)0.074 (5)0.016 (5)−0.007 (5)−0.048 (4)
F40.085 (8)0.067 (5)0.077 (7)−0.003 (6)−0.043 (6)−0.016 (4)
F50.070 (6)0.080 (7)0.059 (5)0.015 (5)−0.024 (5)−0.015 (4)
F60.097 (9)0.078 (5)0.083 (8)−0.014 (6)−0.038 (7)−0.046 (5)
F1'0.041 (3)0.113 (7)0.173 (7)−0.002 (3)−0.039 (3)−0.027 (5)
F2'0.118 (6)0.180 (10)0.147 (8)−0.033 (7)−0.069 (6)−0.036 (7)
F3'0.126 (7)0.088 (4)0.086 (4)0.000 (5)−0.021 (5)−0.058 (3)
F4'0.090 (7)0.068 (4)0.074 (4)0.010 (5)−0.009 (5)−0.022 (3)
F5'0.124 (8)0.077 (4)0.069 (4)−0.014 (6)−0.023 (6)−0.023 (3)
F6'0.074 (6)0.078 (5)0.075 (4)0.002 (4)0.003 (4)−0.043 (3)
C10.064 (3)0.052 (2)0.057 (2)0.0000 (19)−0.015 (2)−0.022 (2)
C20.084 (3)0.086 (3)0.066 (3)−0.017 (3)−0.040 (3)−0.023 (3)
C30.051 (3)0.095 (4)0.066 (3)−0.015 (2)−0.031 (2)−0.002 (3)
C40.042 (2)0.083 (3)0.066 (3)0.014 (2)−0.014 (2)−0.021 (2)
C50.050 (2)0.056 (2)0.053 (2)0.0118 (18)−0.0171 (18)−0.0268 (19)
C60.0340 (19)0.066 (3)0.066 (3)−0.0019 (17)−0.0187 (18)−0.017 (2)
C70.0339 (19)0.074 (3)0.057 (2)0.0055 (18)−0.0156 (17)−0.027 (2)
C80.044 (2)0.082 (3)0.060 (2)0.009 (2)−0.0230 (19)−0.035 (2)

Geometric parameters (Å, °)

P—F1'1.535 (7)C3—C41.350 (7)
P—F61.567 (19)C3—H3A0.9300
P—F2'1.575 (15)C4—C51.379 (6)
P—F31.582 (11)C4—H4A0.9300
P—F21.583 (14)C5—N1.372 (5)
P—F51.588 (16)C5—H5A0.9300
P—F6'1.604 (14)N—C61.476 (5)
P—F4'1.611 (14)C6—C71.518 (6)
P—F41.612 (18)C6—H6A0.9700
P—F5'1.617 (14)C6—H6B0.9700
P—F11.619 (15)C7—C81.534 (5)
P—F3'1.631 (9)C7—H7A0.9700
C1—N1.347 (5)C7—H7B0.9700
C1—C21.375 (6)C8—C8i1.518 (7)
C1—H1A0.9300C8—H8A0.9700
C2—C31.397 (7)C8—H8B0.9700
C2—H2A0.9300
F1'—P—F685.7 (10)F4—P—F183.6 (8)
F1'—P—F2'173.4 (6)F5'—P—F1116.5 (8)
F6—P—F2'95.7 (10)F1'—P—F3'97.5 (6)
F1'—P—F370.4 (7)F6—P—F3'176.5 (11)
F6—P—F3156.1 (13)F2'—P—F3'80.9 (7)
F2'—P—F3107.8 (9)F2—P—F3'78.8 (9)
F1'—P—F2164.7 (6)F5—P—F3'92.5 (8)
F6—P—F298.4 (9)F6'—P—F3'160.7 (10)
F3—P—F2105.1 (10)F4'—P—F3'90.4 (7)
F1'—P—F576.2 (6)F4—P—F3'86.1 (8)
F6—P—F589.5 (10)F5'—P—F3'88.0 (6)
F2'—P—F5110.2 (6)F1—P—F3'112.6 (7)
F3—P—F586.5 (8)N—C1—C2120.6 (4)
F2—P—F589.1 (7)N—C1—H1A119.7
F1'—P—F6'101.7 (9)C2—C1—H1A119.7
F2'—P—F6'80.1 (9)C1—C2—C3118.7 (4)
F3—P—F6'172.1 (12)C1—C2—H2A120.7
F2—P—F6'82.4 (8)C3—C2—H2A120.7
F5—P—F6'91.2 (9)C4—C3—C2119.8 (4)
F1'—P—F4'86.0 (5)C4—C3—H3A120.1
F6—P—F4'88.5 (9)C2—C3—H3A120.1
F2'—P—F4'87.5 (6)C3—C4—C5121.1 (4)
F3—P—F4'88.2 (7)C3—C4—H4A119.4
F2—P—F4'108.7 (6)C5—C4—H4A119.4
F5—P—F4'162.2 (6)N—C5—C4118.6 (4)
F6'—P—F4'91.8 (7)N—C5—H5A120.7
F1'—P—F4104.3 (6)C4—C5—H5A120.7
F6—P—F491.8 (10)C1—N—C5121.2 (3)
F2'—P—F469.2 (7)C1—N—C6120.7 (3)
F3—P—F492.5 (9)C5—N—C6118.1 (3)
F2—P—F490.3 (7)N—C6—C7112.5 (3)
F5—P—F4178.6 (11)N—C6—H6A109.1
F6'—P—F490.0 (9)C7—C6—H6A109.1
F1'—P—F5'95.7 (6)N—C6—H6B109.1
F6—P—F5'93.0 (9)C7—C6—H6B109.1
F2'—P—F5'90.7 (6)H6A—C6—H6B107.8
F3—P—F5'91.0 (7)C6—C7—C8112.7 (3)
F2—P—F5'69.5 (6)C6—C7—H7A109.0
F6'—P—F5'89.2 (8)C8—C7—H7A109.0
F4'—P—F5'177.8 (7)C6—C7—H7B109.0
F4—P—F5'159.8 (6)C8—C7—H7B109.0
F6—P—F169.9 (12)H7A—C7—H7B107.8
F2'—P—F1149.1 (8)C8i—C8—C7113.4 (4)
F3—P—F187.2 (7)C8i—C8—H8A108.9
F2—P—F1166.6 (10)C7—C8—H8A108.9
F5—P—F197.2 (9)C8i—C8—H8B108.9
F6'—P—F185.7 (11)C7—C8—H8B108.9
F4'—P—F165.6 (7)H8A—C8—H8B107.7

Symmetry codes: (i) −x+2, −y+1, −z+1.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
C1—H1A···F4'ii0.932.483.333 (17)153
C2—H2A···F2'iii0.932.533.267 (18)137
C3—H3A···F3'iii0.932.473.257 (15)142
C4—H4A···F1'iv0.932.523.287 (14)140

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

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: HK2581).

References

  • 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.
  • Enraf–Nonius (1989). CAD-4 Software Enraf–Nonius, Delft. The Netherlands.
  • Harms, K. & Wocadlo, S. (1995). XCAD4 University of Marburg, Germany.
  • Jared, L. A., Ding, R. F., Arkady, E. & Daniel, W. A. (2005). J. Am. Chem. Soc. A, 127, 593–604. [PubMed]
  • North, A. C. T., Phillips, D. C. & Mathews, F. S. (1968). Acta Cryst. A24, 351–359.
  • Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. [PubMed]

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