1,1′-[(1,3-Dihydroxypropane-2,2-diyl)dimethylene]dipyridinium bis­(hexa­fluoro­phosphate)

Ai-lin Yuan; Chun-ling Zheng; Ling-hua Zhuang; Chang-sheng Wang; Guo-wei Wang

doi:10.1107/S1600536811013080

. 2011 Apr 13;67(Pt 5):o1104. doi: 10.1107/S1600536811013080

1,1′-[(1,3-Dihydroxypropane-2,2-diyl)dimethylene]dipyridinium bis(hexafluorophosphate)

Ai-lin Yuan ^a, Chun-ling Zheng ^a, Ling-hua Zhuang ^b, Chang-sheng Wang ^a, Guo-wei Wang ^a,^*

PMCID: PMC3089249 PMID: 21754422

Abstract

The title compound, C₁₅H₂₀N₂O₂ ²⁺·2PF₆ ⁻, was prepared by anion exchange of two bromide ions in the ionic liquid 2,2′-bis-(pyridinium-1-ylmethyl)-propane-1,3-diol dibromide with potassium hexafluorophosphate. The two pyridine rings are planar (r.m.s. deviations = 0.008 and 0.00440 Å) and make a dihedral angle of 44.0 (2)°. Intermolecular O—H⋯F and C—H⋯F interactions occur. The four F atoms in each anion were refined as disordered over two sets of sites with an occupancy ration of 0.700 (19):0.300 (19).

Related literature

For properties and applications of ionic liquids, see: Welton (1999 ▶). For dicationic ionic liquids, see: Liang et al. (2008 ▶); Geng et al. (2010 ▶); Yuan et al. (2010 ▶); Yang et al. (2010 ▶). For the synthesis of dicationic ionic liquids, see: Yuan et al. (2010 ▶). For bond-length data, see: Allen et al. (1987 ▶). graphic file with name e-67-o1104-scheme1.jpg

Experimental

Crystal data

C₁₅H₂₀N₂O₂ ²⁺·2PF₆ ⁻
M _r = 550.27
Monoclinic,
a = 11.955 (2) Å
b = 13.796 (3) Å
c = 12.707 (3) Å
β = 95.17 (3)°
V = 2087.3 (7) Å³
Z = 4
Mo Kα radiation
μ = 0.33 mm⁻¹
T = 293 K
0.30 × 0.20 × 0.10 mm

Data collection

Enraf–Nonius CAD-4 diffractometer
Absorption correction: ψ scan (North et al., 1968 ▶) T _min = 0.907, T _max = 0.968
4027 measured reflections
3835 independent reflections
2564 reflections with I > 2σ(I)
R _int = 0.031
3 standard reflections every 200 reflections intensity decay: 1%

Refinement

R[F ² > 2σ(F ²)] = 0.053
wR(F ²) = 0.141
S = 1.04
3835 reflections
372 parameters
H-atom parameters constrained
Δρ_max = 0.36 e Å⁻³
Δρ_min = −0.26 e Å⁻³

Data collection: CAD-4 EXPRESS (Enraf–Nonius, 1994 ▶); cell refinement: CAD-4 EXPRESS; 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 global, I. DOI: 10.1107/S1600536811013080/im2266sup1.cif

e-67-o1104-sup1.cif^{(23.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536811013080/im2266Isup2.hkl

e-67-o1104-Isup2.hkl^{(188KB, 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
C6—H6B⋯O1	0.97	2.47	2.831 (5)	102
C10—H10B⋯O2	0.97	2.44	2.796 (5)	102
O1—H1A⋯F8ⁱ	0.82	2.29	2.898 (8)	131
O2—H2A⋯F1	0.82	2.49	2.973 (11)	119
C1—H1B⋯F6	0.93	2.40	3.280 (4)	158
C11—H11A⋯F10ⁱ	0.93	2.31	3.087 (7)	141

Open in a new tab

Symmetry code: (i) Inline graphic .

Acknowledgments

We acknowledge the National Natural Science Foundation of China (No. 51003047) and the Foundation for Young Teachers Scholarship of Nanjing University of Technology, Jiangsu, China (No. 39729005) for financial support. The authors thank the Centre of Testing and Analysis, Nanjing University, for the data collection.

supplementary crystallographic information

Comment

Ionic liquids (ILs) have enjoyed vast research interests in recent years because of their unique physicochemical properties (Welton, 1999). Geminal dicationic ionic liquids have been shown to possess superior properties in terms of thermal stability and volatility compared to traditional ionic liquids (ILs) (Liang et al., 2008). Consequently, they have been proposed as solvents in high-temperature reactions, as novel high-temperature lubricants or ultrastable separation phases (Yang et al., 2010).

As part of our ongoing studies on new geminal dicationic ionic liquids (Geng et al., 2010; Yuan 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. Intramolecular C—H···O hydrogen bonds are observed between the methylene groups next to the pyridine N atoms ans the hydroxy groups. All bond lengths are within normal ranges (Allen et al., 1987). The two pyridine rings are planar (r.m.s. deviations = 0.008 and 0.004 Å) and make a dihedral angle of 44.0 (2)°. (Table 1, Fig. 1).

Experimental

A mixture of pyridine (1.98 g, 25 mmol) and 2,2-bis-(bromomethyl)-propane-1,3-diol (2.60 g, 10 mmol) was stirred vigorously at 387 K for 16 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) (4.82 g, 88%). M.p. 508–510 K. Crystals of (I) suitable for X-ray diffraction were obtained by slow evaporation of a methanolic solution. ¹H NMR (DMSO, δ, p.p.m.) 8.92 (t, 4 H), 8.68 (m, 2 H), 8.20 (m, 4 H), 5.57 (s, 2 H) 4.79 (s, 4 H), 3.16 (s, 4 H).