4-Fluoroanilinium tetrachloridoferrate(III) 18-crown-6 clathrate

The reaction of 4-fluoroaniline hydrochloride, 18-crown-6 and ferric chloride in methanolic solution yields the title compound, (C6H7FN)[FeCl4]·C12H24O6, which has an unusual supramolecular structure. N—H⋯O hydrogen-bonding interactions between the NH3 + substituents of the 4-fluoroanilinium cations and the O atoms of the crown ether molecules result in a rotator–stator-like structure.

The reaction of 4-fluoroaniline hydrochloride, 18-crown-6 and ferric chloride in methanolic solution yields the title compound, (C 6 H 7 FN) [FeCl 4 ]ÁC 12 H 24 O 6 , which has an unusual supramolecular structure. N-HÁ Á ÁO hydrogen-bonding interactions between the NH 3 + substituents of the 4-fluoroanilinium cations and the O atoms of the crown ether molecules result in a rotator-stator-like structure.

Experimental
Crystal data (C 6 Table 1 Hydrogen-bond geometry (Å , ).  (Fender et al. 2002). Both the size of the crown ether and the nature of the ammonium cation (-NH 4 + , RNH 3 + , etc) can influence the stoichiometry and stability of these host-guest complexes. The host molecules combine with the guest species by intermolecular interactions, and if the host molecule possess some specific sites (by chelate effect), it is easy to realise high selectivity in ion or molecular recognitions.18-crown-6 have the highest affinity for ammonium cation RNH 3 + and most studies of 18-crown-6 and its derivatives invariably showed a 1:1 stoichiometry with RNH 3 + cations.
In continuation of our investigations on ferroelectric phase transitions materials the dielectric permittivity of the title compound was tested (Fu et al. 2007;Ye et al. 2009;Zhang et al. 2009). The title compound shows no dielectric anomalies with values of 6-8 and 7-10 in the temperature ranges from 80 to 300 K and 300 K to 400 K (below the compound melting point 433 K), respectively. These findings suggest that the compound should exhibit no distinct phase transition within the measured temperature range.  Experimental p-F-C 6 H 4 -NH 2 × HCl (2 mmol, 0.295 g) and 18-crown-6 (2 mmol, 0.528 g) were dissolved in methanol. After addition of ferric chloride (2 mmol, 0.54 g) in concentrated hydrochloric acid, a precipitate (yield is about 95%) was formed, filtered supplementary materials sup-2 and washed with a small amount of methanol. Single crystals suitable for X-ray diffraction analysis were obtained from slow evaporation of methanol and DMF (v/v 3/1) from the solution at room temperature after two days.

Refinement
All hydrogens were were calculated geometrically. The positions of the H atoms of the nitrogen atoms were refined using a riding model with N-H = 0.89 Å and U iso (H) = 1.5U eq (N). C-H groups were also refined using a riding model for hydrogen atoms with C-H distances ranging from 0.93 to 0.97 Å and U iso (H) = 1.2Ueq(C).
Figures Fig. 1. The molecular structure of the title compound, with the atomic numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.

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 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 Rfactors(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.