4-Allylmorpholin-4-ium bromide

The title compound, C7H14NO+·Br−, was formed by reaction of 4-allylmorpholine and hydrogen bromide. In the crystal, molecules are connected via N—H⋯Br and C—H⋯Br hydrogen bonds, forming a three-dimensional network.

The title compound, C 7 H 14 NO + ÁBr À , was formed by reaction of 4-allylmorpholine and hydrogen bromide. In the crystal, molecules are connected via N-HÁ Á ÁBr and C-HÁ Á ÁBr hydrogen bonds, forming a three-dimensional network.

Meng Ting Han Comment
At present, much attention in ferroelectric material field is focused on developing ferroelectric pure organic or inorganic compounds (Haertling et al. 1999;Homes et al. 2001). Recently we have reported the synthesis of a variety of compounds Hang et al., 2009), which have potential piezoelectric and ferroelectric properties. In order to find more dielectric ferroelectric materials, we investigate the physical properties of the title compound ( Fig. 1). The dielectric constant of the title compound as a function of temperature indicates that the permittivity is basically temperature-independent (dielectric constant equaling to 0.6 to 1.42), suggesting that this compound should be not a real ferroelectrics or there may be no distinct phase transition occurred within the measured temperature range. Similarly, below the melting point (408 K) of the compound, the dielectric constant as a function of temperature also goes smoothly, and there is no dielectric anomaly observed (dielectric constant equaling to 0.6 to 1.42).Herein, we report the synthesis and crystal structure of the title compound.
As can be seen from the packing diagram ( Fig. 2), molecules are connected via intermolecular N-H···Br and C-H···Br hydrogen bonds to form a three-dimensional network. Dipole-dipole and van der Waals interactions are also operative in organizing the molecular packing.

Experimental
A mix of 4-allylmorpholine (0.762 g, 0.006 mol) and hydrogen bromide (1.212 g, 0.006 mol) in water (20 ml) was stirred until clear. After several days, the title compound was formed and recrystallized from solution to afford red prismatic crystals suitable for X-ray analysis.

Refinement
H atoms were positioned geometrically and refined using a riding model, with C-H = 0.97 Å and U iso (H) = 1.2 eq (C).

Computing details
Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure:   The crystal packing of the title compound viewed along the a axis showing the hydrogen bonding network. Some of the H-atoms have been ommitted for clarity.

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 > σ(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.