Butane-1,4-diammonium hexafluorosilicate

The title compound, [NH3(CH2)4NH3]2+·SiF6 2−, is a hybrid built from an organic butane-1,4-diammonium dication linked to a hexafluorosilicate mineral anion. Both ions posses inversion symmetry. In the anion the Si atom is located on an inversion center, while in the cation the center of inversion is situated at the mid-point of the central —CH2—CH2— bond. The Si atom is surrounded by six F atoms, forming a slightly distorted SiF6 2− octahedron. These octahedra are linked to the organic cations through N—H⋯F hydrogen bonds, forming a three-dimensional network.

The title compound, [NH 3 (CH 2 ) 4 NH 3 ] 2+ ÁSiF 6 2À , is a hybrid built from an organic butane-1,4-diammonium dication linked to a hexafluorosilicate mineral anion. Both ions posses inversion symmetry. In the anion the Si atom is located on an inversion center, while in the cation the center of inversion is situated at the mid-point of the central -CH 2 -CH 2bond. The Si atom is surrounded by six F atoms, forming a slightly distorted SiF 6 2À octahedron. These octahedra are linked to the organic cations through N-HÁ Á ÁF hydrogen bonds, forming a three-dimensional network.
Te and X: Cl, Br, I and F, have recently attracted the interest of many investigators due to their potential physical properties (Ouasri et al., 2003;Elyoubi et al., 2004). X-ray, thermal and vibrational studies of phase transitions have also been performed for highly related compounds belonging to the alkanediammonium halogenobismuthate salts family as the pentachlorobismuthate one (NH 3 (CH 2 ) n NH 3 )BiCl 5 (Jeghnou et al., 2005;Ouasri et al., 2012;Rhandour et al., 2011;Ouasri et al., 2013a;Ouasri et al., 2013b;Ouasri et al., 2014). The aim of the present paper was to study the recently synthesized butanediammonium hexafluorosilicate (NH 3 (CH 2 ) 4 NH 3 )SiF 6 crystal, by X-ray diffraction at room temperature.
The structure of the title compound is built up from inorganic anions linked to the organic cations trough hydrogen bonds. In this structure, all atoms are in general positions, except the silicon atom (Si1 (1/2, 0, 0) which is located at a crystallographic centre of inversion of the P1 space group. In addition, the centre of the bond C2-C2i is also situated on another crystallographic centre of inversion. The asymmetric unit therefore contains only one half of the organic cation and one SiF 3 moiety. The remaining atoms of the unit cell are generated by symmetry operations.
The silicon atom is surrounded by six fluorine atoms building a slightly distorted SiF 6 2octahedron. SiF 6 2octahedra are linked to the organic cations through N-H···F hydrogen bonds producing an infinite two-dimensional layer parallel to (0 1 1) ( Fig.2 and Table 1).

Refinement
H atoms were located in a difference map and treated as riding with C-H = 0.97 Å, and 0.893 Å for CH 2 and N-H, respectively. Thermal parameters of all hydrogen atoms were refeined with U iso (H) = 1.2 U eq (methylene) and U iso (H) = 1.5 U eq (N) for the ammonium groups.

Computing details
Data collection: APEX2 (Bruker, 2009); cell refinement: SAINT (Bruker, 2009); data reduction: SAINT (Bruker, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 for Windows (Farrugia, 2012); software used to prepare material for publication: PLATON (Spek, 2009) and publCIF (Westrip, 2010).    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 > 2σ(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.