Bis(4-methylmorpholin-4-ium) tetrabromidozincate(II)

The title compound, (C5H12NO)2[ZnBr4], was synthesized by hydrothermal reaction of ZnBr2 with 4-methylmorpholine in a HBr/distilled water solution. Each of the two independent cations exhibits a chair conformation; the anion deviates slightly from an tetrahedral configuration. The Zn—Br distances in the anion are in the range of 2.3996 (9)–2.4247 (9) Å. All of the amine H atoms are involved in bifurcated intermolecular N—H⋯Br hydrogen bonds, building up a trimer.

The title compound, (C 5 H 12 NO) 2 [ZnBr 4 ], was synthesized by hydrothermal reaction of ZnBr 2 with 4-methylmorpholine in a HBr/distilled water solution. Each of the two independent cations exhibits a chair conformation; the anion deviates slightly from an tetrahedral configuration. The Zn-Br distances in the anion are in the range of 2.3996 (9)-2.4247 (9) Å . All of the amine H atoms are involved in bifurcated intermolecular N-HÁ Á ÁBr hydrogen bonds, building up a trimer.

Comment
The amino derivatives have found wide range of applications in material science, such as magnetic, fluorescent and dielectric behaviors. And there has been an increased interest in the preparation of amino coordination compound (Aminabhavi et al., 1986;Fu, et al. 2009). We report here the crystal structure of the title compound,  tetrabromidozincate(II).
The asymmetric unit is composed of one ZnBr 4 2anion and two 4-methylmorpholin-4-ium cations ( Fig.1). Both the amine N atoms were protonated, thus indicating two positive charge in all. And the ZnBr 4 2anion was showing two negative charge to make the charge balance. The geometric parameters of the title compound are in the normal range.
In the crystal structure, all the H atoms of amine groups are involved in intermolecular N-H···Br hydrogen bonds building up a trimer (Table 1 and Fig.2).

Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.97 Å(methylene) and C-H = 0.96 Å(methyl) with U iso (H) = 1.2U eq (methylene) and U iso (H) = 1.5U eq (methyl). The positional parameters of the H atoms (N1, N2) were refined freely. And in the last stage of the refinement, it were restrained with the H-N = 0.90 (2)Å),

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.
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 > 2sigma(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.