Bis(diisopropylammonium) hexachloridostannate(IV)

The title compound, (C6H16N)2[SnCl6], crystallizes with one diisopropylammonium cation lying on a general position and the hexachloridostannate(IV) anion about a centre of inversion. The [SnCl6]2− anion undergoes a slight distortion from octahedral symmetry as the result of the formation of four unforked charge-supported N—H⋯Cl hydrogen bonds. The hydrogen bonds between the cations and anions form layers perpendicular to [101]. These layers are built by 24-membered rings which can be classified with an R 8 8(24) graph-set descriptor. According to this hydrogen-bonding motif, the title compound is isostructural with (C6H16N)2[IrCl6].

The title compound, (C 6 H 16 N) 2 [SnCl 6 ], crystallizes with one diisopropylammonium cation lying on a general position and the hexachloridostannate(IV) anion about a centre of inversion. The [SnCl 6 ] 2À anion undergoes a slight distortion from octahedral symmetry as the result of the formation of four unforked charge-supported N-HÁ Á ÁCl hydrogen bonds. The hydrogen bonds between the cations and anions form layers perpendicular to [101]. These layers are built by 24membered rings which can be classified with an R 8 8 (24) graphset descriptor. According to this hydrogen-bonding motif, the title compound is isostructural with (C 6 H 16 N) 2 [IrCl 6 ].

Experimental
Crystal data (C 6 Table 1 Hydrogen-bond geometry (Å , ).  (Reiss & Helmbrecht, 2012). Recently the simple dipH chloride has attracted much attention as it is a ferroelectric solid with a high phase transition temperature (Fu et al., 2011). This study on (dipH) 2 [SnCl 6 ] is part of our long standing interest on the principles of arrangement of simple dipH salts (Reiss & Meyer, 2011).
The title compound (dipH) 2 [SnCl 6 ] crystallizes with one dipH cation in a general position and one [SnCl 6 ] 2anion located on a center of inversion. The C-N and C-C bond lengths and the bond angles of the cation are in the expected range. The [SnCl 6 ] 2anion adopts a distorted octahedral geometry (angles between 89.00 (1) and 91.00 (1)°). The cations and anions are connected by medium-strong, charge-supported hydrogen bonds (Table 1) between the NH 2 + groups and their neighbouring chlorine atoms (Fig. 1). Only four out of six chlorido ligands of each [SnCl 6 ] 2anion are involved with the Sn-Cl bonds participating in hydrogen bonding significantly longer (2.4359 (3) and 2.4527 (3) Å) than the two others (2.4055 (3) Å). This bonding situation results in the formation of two-dimensional layers in the [101] plane, whose characteristic motif is an annealed, 24-membered, wavy, hydrogen bonded ring ( Fig. 1) with the graph-set descriptor R 8 8 (24) (Etter et al., 1990). This second level graph-set is shown in Fig. 2 as part of the constructor graph (Grell et al. 2002). The two other representative second level graph-sets are C 4 4 (12) which run along [11-1] and C 2 2 (6) which represents the bent connection of one [SnCl 6 ] 2anion with two dipH cations. The shortest H···Cl distance of the Cl3 is with 2.938 (16) Å roughly 0.5 Å longer than the two other H···Cl bonds. The acute N-H···Cl3 angle of 131.7 (12) ° supports our interpretation that the Cl3 atom is not involved in any significant hydrogen bond.
Additionally a medium-strong band at 170 cm -1 is assigned to the ν 4 mode which becomes Raman-active due to the

Refinement
All hydrogen atoms were identified in difference syntheses. The hydrogen atoms of the methyl groups were idealized and refined using rigid groups allowed to rotate about the C-C bond (AFIX 137 option of the SHELXL97 programme). For each methyl group one common U iso value was refined. The coordinates of hydrogen atoms belonging to the CH and NH 2 groups were refined freely. The U iso (H) values of the two hydrogen atoms of the NH 2 group were refined unrestricted.    Constructor graph (Grell et al., 2002) of that part of the title structure shown in Fig.1.

Special details
Experimental. Absorption correction: CrysAlisPro (Oxford Diffraction, 2009). Numerical absorption correction based on gaussian integration over a multifaceted crystal model. 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 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.