1,4-Diazoniabicyclo[2.2.2]octane tetrachloroiodate(III) chloride

In the title compound, C6H14N2 2+·Cl4I−·Cl−, the dication and the anions lie on special positions. The dication has mm2 symmetry with two bonded C atoms and the two N atoms located on a crystallographic mirror plane parallel to bc, and with a mirror plane parallel to ab passing through the mid points of the three C—C bonds. In the square-planar Cl4I− anion, two Cl atoms and the I atom are located on the mm2 axis; the other two Cl atoms are disordered over two postions of equal occupancy (0.25) across the mirror parallel to the ab plane. The Cl− anion is located on the mm2 axis. The crystal structure is stabilized by intermolecular N—H⋯Cl hydrogen bonds.

In the title compound, C 6 H 14 N 2 2+ ÁCl 4 I À ÁCl À , the dication and the anions lie on special positions. The dication has mm2 symmetry with two bonded C atoms and the two N atoms located on a crystallographic mirror plane parallel to bc, and with a mirror plane parallel to ab passing through the mid points of the three C-C bonds. In the square-planar Cl 4 I À anion, two Cl atoms and the I atom are located on the mm2 axis; the other two Cl atoms are disordered over two postions of equal occupancy (0.25) across the mirror parallel to the ab plane. The Cl À anion is located on the mm2 axis. The crystal structure is stabilized by intermolecular N-HÁ Á ÁCl hydrogen bonds.

Comment
Ferroelectric materials continue to attract much attention due to their potential applications in memory devices (Scott, 2007).
Recently, diazabicyclo[2.2.2]octane (dabco) salts with inorganic tetrahedral anions having potassium dihydrophosphate-type (KDP-type) structures have been found to exhibit exceptional dielectric properties (Katrusiak & Szafrański, 2006). In our laboratory, the title compound containing a diprotonated cation, C 6 H 14 N 2 2+ , a tetrachloroiodate and a Clanions, has been synthesized. In this article, the crystal structure of the title compound is reported.
In the title compound ( Fig. 1), all the species lie on special positions with only one quarter of each being part of the asymmetric unit. The I(III) ion in a square-planar coordination environment. The Cl3 atom is disordered. The crystal structure is stabilized by intermolecular N-H···Cl hydrogen bonds (Table 1).
Experimental KI (0.5 g) and I 2 (0.7 g) were dissolved in a solution of ethanol (30 ml) and conc. HCl (13 ml) (36%). After addition of 1,4-diazoniabicyclo[2.2.2]octane (1 g) to the above solution, the mixture was stirred for 1 h and then filtered. The filtrate was left at room temperature to allow the solvent to evaporate. Yellow transparent block crystals were obtained after one weeks.

Refinement
All H atoms were placed in calculated positions with C-H = 0.97 Å and N-H = 0.91 Å, and refined using a riding model, with U iso (H) = 1.2U eq (C/N). The Cl3 atom was disordered over two sites Figures   Fig. 1. The title compound with atomic labels; displacement ellipsoids were 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.  (2)