4-Amidinopyridinium hexachloridostannate(IV) dihydrate

The organic cation in the title compound shows whole-molecule disorder.


Structure description
The title hydrated molecular salt, with formula (C 6 H 9 N 3 )Á[SnCl 6 ]Á2H 2 O, crystallizes in the triclinic space group P1. The asymmetric unit is constituted by a Sn 0.5 Cl 3 fragment (Sn site symmetry 1), a 4-amidinopyridinium cation (twice protonated at N1 and N2) and a water molecule, as shown in Fig. 1.
The cation shows whole-molecule disorder about an inversion centre and the water molecule is disordered over adjacent positions (OÁ Á ÁO = 1.13 Å ) and there is also static disorder of two of the chloride ions of the anion. With the exception of Cl3, where the occupancy ratio is 0.67/0.33 (for Cl3A/Cl3B), each disordered atom is shared between two crystallographic sites with occupancies of 0.50. There are no abnormalities in the bond lengths and angles and they are comparable to those of similar types (Liu et al., 2011;Ghallab et al., 2020).
In the extended structure, cationic and anionic layers occur, with water molecules intercalating between them as shown in the projection of the structure onto the ac and bc planes (Figs. 2 and 3). Cohesion in the crystal is ensured by numerous hydrogen bonds ( Table 1)

Synthesis and crystallization
Following the method of preparation described in the literature (Bouchene et al., 2018), the compound was synthesized via the aqueous technique. A millimeter-sized transparent crystal was formed after three months of slow evaporation at ambient temperature. Refinement Crystal data, data collection and structure refinement details are summarized in Table 2. The disordered atoms were treated with constraints on distances and angles (by the SAME command and PART options). With the exception of Cl3, where the ratio is 0.67/0.33, each disordered atom is shared between two crystallographic sites with occupancy rates of 0.50.

Figure 1
The molecular structure showing 30% displacement ellipsoids.

Figure 2
Projection of the crystal packing on the ac plane.  where P = (F o 2 + 2F c 2 )/3 (Δ/σ) max < 0.001 Δρ max = 1.22 e Å −3 Δρ min = −1.35 e Å −3 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.