5-(Pyridinium-3-yl)tetrazol-1-ide hexaaquamagnesium dichloride

In the title compound, (C6H5N5)2[Mg(H2O)6]Cl2, the asymmetric unit contains one zwitterionic 5-(pyridinium-3-yl)tetrazol-1-ide molecule, one half of an [Mg(H2O)6]2+ cation ( symmetry) and one chloride ion. The MgII ion is surrounded by six water molecules, with their O atoms located at the apices, exhibiting a slightly distorted octahedral coordination. Mg—O bond lengths range from 2.0526 (14) to 2.0965 (16) Å [mean value = 2.068 Å]. The pyridine and tetrazole rings are nearly coplanar and only twisted from each other by a dihedral angle of 5.68 (1)°. The zwitterionic organic molecules, anions and cations are connected by O—H⋯Cl, O—H⋯N and N—H⋯Cl hydrogen bonds, leading to the formation of a three-dimensional network.

In the title compound, (C 6 H 5 N 5 ) 2 [Mg(H 2 O) 6 ]Cl 2 , the asymmetric unit contains one zwitterionic 5-(pyridinium-3-yl)tetrazol-1-ide molecule, one half of an [Mg(H 2 O) 6 ] 2+ cation (1 symmetry) and one chloride ion. The Mg II ion is surrounded by six water molecules, with their O atoms located at the apices, exhibiting a slightly distorted octahedral coordination. Mg-O bond lengths range from 2.0526 (14) to 2.0965 (16) Å [mean value = 2.068 Å ]. The pyridine and tetrazole rings are nearly coplanar and only twisted from each other by a dihedral angle of 5.68 (1) . The zwitterionic organic molecules, anions and cations are connected by O-HÁ Á ÁCl, O-HÁ Á ÁN and N-HÁ Á ÁCl hydrogen bonds, leading to the formation of a three-dimensional network.

Comment
Tetrazole compounds have attracted more attention as phase transition dielectric materials for its application in micro-electronics, memory storage. With the purpose of obtaining phase transition crystals of 3-(1H-tetrazol-5-yl)pyridine compounds, its interaction with various metal ions has been studied and a series of new materials have been elaborated with this organic molecule (Zhao et al., 2008;Fu et al., 2007;. In this paper, we describe the crystal structure of the title compound, 3-(pyridinium-5-yl)tetrazol-1-ide hexaaquamagnesium(II) dichloride.
In the title compound, (C 6 H 5 N 5 ) 2 .[Mg(H 2 O) 6 ] 2+ .2Cl, the asymmetric unit consists of one zwitterionic 3-(pyridinium-5-yl)tetrazol-1-ide molecule, one half of an [Mg(H 2 O) 6 ] 2+ cation ( 1 symmetry) and one chloride ion. The magnesium(II) ion is surrounded by six water molecules with their O atoms located at the apices exhibiting a slightly distorted octahedral coordination. Mg-O bond distances range from 2.0526 (14) to 2.0965 (16)Å (mean value 2.0681 (15)Å). In the zwitterionic organic molecules, the pyridine and tetrazole rings are nearly coplanar and only twisted from each other by a dihedral angle of 5.68 (1)°. The geometric parameters of the tetrazole rings are comparable to those in related molecules (Zhao et al., 2008;Fu et al., 2009).

Experimental
MgCl 2 .6H 2 O (2 mmol) and 3-(1H-tetrazol-5-yl)pyridine (2 mmol, 0.528 g) were dissolved in 70% methanol aqueous solution, and them 2 ml HBr was added. Single crystals suitable for X-ray diffraction analysis were obtained from slow evaporation of the solution at room temperature after two weeks.

Refinement
All H atoms attached to C and N atoms were fixed geometrically and treated as riding with C-H = 0.93 Å (aromatic) and N-H = 0.86 Å with U iso (H) = 1.2U eq (C or N). All aqueous hydrogen atoms were calculated geometrically, O-H = 0.85 Å and were refined using a riding model and U iso (H) = 1.5U eq (O). Fig. 1. A view of the title compound with the atomic numbering scheme. Displacement ellipsoids were drawn at the 30% probability level.