Bis(2,6-dimethylpyridinium) tetrabromidozincate(II)

In the crystal structure of the title compound, (C7H10N)2[ZnBr4], the coordination geometry of the anion is approximately tetrahedral and a twofold rotation axis passes through the Zn atom. The Zn—Br bond lengths range from 2.400 (2) to 2.408 (3) Å and the Br—Zn—Br angles range from 108.14 (6) to 115.15 (15)°. In the crystal structure, the [ZnBr4]2− anion is connected to two cations through N—H⋯Br and H2C—H⋯Br hydrogen bonds, forming two-dimensional cation–anion–cation layers normal to the b axis. No significant Br⋯Br interactions [the shortest being 4.423 (4) Å] are observed in the structure.

In the crystal structure of the title compound, (C 7 H 10 N) 2 - [ZnBr 4 ], the coordination geometry of the anion is approximately tetrahedral and a twofold rotation axis passes through the Zn atom. The Zn-Br bond lengths range from 2.400 (2) to 2.408 (3) Å and the Br-Zn-Br angles range from 108.14 (6) to 115.15 (15) . In the crystal structure, the [ZnBr 4 ] 2À anion is connected to two cations through N-HÁ Á ÁBr and H 2 C-HÁ Á ÁBr hydrogen bonds, forming twodimensional cation-anion-cation layers normal to the b axis. No significant BrÁ Á ÁBr interactions [the shortest being 4.423 (4) Å ] are observed in the structure.
Al al-Bayt University and Al-Balqa'a Applied University are thanked for supporting this work. We also thank Professor S. F. Haddad for helpful discussions.
Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: AT2771).
Bis(2,6-dimethylpyridinium) tetrabromidozincate(II) B. F. Ali and R. Al-Far Comment Non-covalent interactions play an important role in organizing structural units in both natural and artificial systems . They exercise important effects on the organization and properties of many materials in areas such as biology (Hunter 1994;Desiraju & Steiner 1999), crystal engineering (see for example: Allen et al., 1997;Dolling et al., 2001) and material science (Panunto et al., 1987;Robinson et al., 2000). The interactions governing the crystal organization are expected to affect the packing and then the specific properties of solids. In connection with ongoing studies Ali et al., 2008;Al-Far & Ali, 2009) of the structural aspects of halo-metal anion salts, we herein report the crystal structure of title compound (I).
The asymmetric unit in (I), contains half an anion and one cation (Fig. 1). The geometry of ZnBr 4 2anions is approximately tetrahedral and a twofold rotation axis passes through the Zn II ion ( Table 1). The Zn-Br bonds range from 2.400 (2) to 2.408 (3) Å and the Br-Zn-Br angles range from 108.14 (6) to 115.15 (15)°. The bond distances and angles fall in the range of those reported previously for compounds containing Zn-Br anions (Gao et al., 2007). In the cation, the bond lengths and angles are within normal range (Allen et al., 1987).
The packing of the structure (  (Table 2). These interactions link anions and cations into two-dimensional cation···anion···cation layers normal to the crystallographic b axis (Fig. 2).
The N-H···Br and C-H···Br hydrogen bonding are potential building blocks for this stable supramolecular lattice. The stability of this lattice is evident in the isostructurality with the reported analogue (Ali et al., 2008).

Experimental
Warm solution of ZnCl 2 (1.0 mmol) dissolved in absolute ethanol (10 ml) and HBr (60%, 5 ml), was mixed with a stirred hot solution of 2,6-dimethylpyridine (2 mmol) dissolved in ethanol (10 ml). The mixture was then refluxed for 2 h, and then allowed to evaporate undisturbed at room temperature. The salt crystallized over 3 d as nice colourless crystals. and allowed to ride on their parent atoms with U iso fixed at 1.2 or 1.5 U eq (C,N).  Fig. 1. A view of the asymmetric unit of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry operation A: -x + 1, y, -z + 1/2]. Bis(2,6-dimethylpyridinium) tetrabromidozincate(II) Crystal data (C 7