Bis(2-bromopyridinium) hexachloridostannate(IV)

The asymmetric unit of the title compound, (C5H5BrN)2[SnCl6], contains one cation and one half-anion. The [SnCl6]2− anion is located on an inversion center and forms a quasi-regular octahedral arrangement. Hydrogen-bonding interactions of two kinds, viz. N—H⋯Cl—Sn and C—H⋯Cl—Sn, along with Cl⋯Br interactions [3.4393 (15) Å], connect the ions in the crystal structure into two-dimensional supramolecular arrays. These supramolecular arrays are arranged in layers approximately parallel to (110) built up from anions interacting with six symmetry-related surrounding cations.

The asymmetric unit of the title compound, (C 5 H 5 BrN) 2 [SnCl 6 ], contains one cation and one half-anion. The [SnCl 6 ] 2À anion is located on an inversion center and forms a quasi-regular octahedral arrangement. Hydrogenbonding interactions of two kinds, viz. N-HÁ Á ÁCl-Sn and C-HÁ Á ÁCl-Sn, along with ClÁ Á ÁBr interactions [3.4393 (15) Å ], connect the ions in the crystal structure into two-dimensional supramolecular arrays. These supramolecular arrays are arranged in layers approximately parallel to (110) built up from anions interacting with six symmetryrelated surrounding cations.
Al al-Bayt University and Al-Balqa'a Applied University are thanked for supporting this work Hybrid organic-inorganic compounds are of great interest owing to their ionic, electrical, magnetic and optical properties (Hill, 1998;Kagan et al., 1999;Raptopoulou et al., 2002). Tin metal-halo based hybrids are of particular interest as being materials with interesting optical and magnetic properties (Aruta et al., 2005;Knutson et al., 2005;Mitzi et al., 2001;Kagan et al., 1999). We are currently carrying out studies about lattice including different types of intermolecular interactions. Our strategy is to use aromatic compounds to encourage aryl···aryl packing arrangements of various types, using substituted pyridinium in order to facilitates associations, and halo salts that can involve in X···X interactions as The asymmetric unit of (I) contains one cation and one-half anion (Fig. 1). The (SnCl 6 ) 2anion lies on an inversion center, in a quasi-octahedral geometry ( Table 1). The Sn-Cl bond lengths are almost invariant, but Sn-Cl2 is longer than the others (involved in the shortest hydrogen bonds). These lengths fall within the range of tin-chloride distances reported previously for compounds containing (SnCl 6 ) 2anions (Bouacida et al., 2007;Ellis & Macdonald, 2006;Li et al., 2005;Willett & Haddad, 2000). Bond lengths and angles within the cation are as expected (Allen et al., 1987).
The packing of the structure (Fig. 2) can be described as layers of alternating anions (zigzag orientation) along the face parallel to b-axis and diagonal to ac plane. Each (SnCl 6 ) 2anion is surrounded by six cations via four equatorial (C,N)-H···Cl interactions (Table 2) and two axial Cl···Br interactions [Cl3···Br2 i = 3.4393 (15) Å; symmetry code: (i) -1/2 + x, -1/2 -y, -1/2 + z; Fig. 3). This arrangement of molecules appears as layers approximately parallel to [110]. It is noteworthy that structural and theoretical results (Awwadi et al., 2007; and references therein), show the significance of linear C-Y···X -(in this case C-Cl···Br) synthons in influencing structures of crystalline materials and in use as potential building blocks in crystal engineering via supramolecular synthesis.
The intermolecular hydrogen bonds (Table 2) and Cl···Br interactions would therefore add some lattice stability. This is evident in the isostructurality with the reported Te analogue (Fernandes et al., 2004).

S2. Experimental
Warm solution of SnCl 4 (1.0 mmol) dissolved in absolute ethanol (10 ml) and concentrated HCl (1 ml), was added dropwise to a stirred hot solution of 2-bromopyridine (1 mmol) dissolved in ethanol (10 ml). The mixture was treated with another 2 ml of concentrated HCl and refluxed for 2 h, then cooled, filtered off, and allowed to stand undisturbed at room temperature. The salt crystallized over 1 d as nice yellow block crystals (yield: 89.6%).

S3. Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH) and C-H = 0.93 Å for aromatic H, and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C, N).