9,10-Bis{2-[1-(2-pyridylmethyl)imidazolium-3-yl]ethoxy}anthracene bis(hexafluoridophosphate)

The cation of the title compound, C36H34N6O2 2+·2PF6 −, lies across a crystallographic inversion centre. The imidazole and pyridine rings form dihedral angles of 82.28 (5)° and 11.87 (7)°, respectively, with the anthracene ring system. The crystal packing is stabilized by π–π interactions between the pyridine ring and the central ring of anthracene, with a ring centroid–centroid distance of 3.684 (3) Å. The PF6 − anion is disordered over three different positions with occupancies of 0.284 (6), 0.354 (8) and 0.362 (9).


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The asymmetric unit of the title compound contains one-half of the organic cation and a PF 6 counter ion. The cation lies on a crystallographic inversion center. Bond lengths and angles in the title molecule ( Fig. 1) are within normal ranges.
The imidazole ring is almost perpendicular to the anthracene ring system, with a dihedral angle of 82.28 (5)°, and the pyridine ring is almost parallel to the anthracene ring system, with a dihedral angle of 11.87 (7)°. The crystal packing is stabilized by π-π interactions between pyridine ring and central ring of anthracene [centroid-centroid distance is 3.684 (3) %A.

S2. Experimental
The title compound was prepared according to the reported procedure of Liu et al. (2003). Yellow single crystals suitable for X-ray diffraction were obtained by recrystallization from acetonitrile.
The P-F distances were restrained to 1.56 (1) Å, and the displacement parameters of disordered F atoms were restrained to an approximate isotropic behaviour, and also restrained to have the same U ij components. H atoms were placed in calculated positions with C-H = 0.93-0.97 Å, and refined using a riding model approximation, with U iso (H) = 1.2 eq (C).  View of the cationic unit in the title compound. Displacement ellipsoids are drawn at the 30% probability level.

9,10-Bis{2-[1-(2-pyridylmethyl)imidazolium-3-yl]ethoxy}anthracene bis(hexafluoridophosphate)
Crystal data C 36 H 34 N 6 O 2 2+ ·2PF 6 − M r = 872.63 Triclinic, P1 Hall symbol: -P 1 a = 8.829 (4) Å b = 9.811 (4) Å c = 12.586 (5) Å α = 72.382 (7) 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 F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.