Cyanomethanaminium tetrafluoroborate

In the title compound, C2H5N2 +·BF4 −, the cations and anions are connected via intermolecular N—H⋯F and C—H⋯F hydrogen bonds, forming a three-dimensional network.

In the title compound, C 2 H 5 N 2 + ÁBF 4 À , the cations and anions are connected via intermolecular N-HÁ Á ÁF and C-HÁ Á ÁF hydrogen bonds, forming a three-dimensional network.

Comment
At present, much attention in ferroelectric material field is focused on developing ferroelectric pure organic or inorganic compounds (Haertling, 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 have investigate the physical properties of the title compound. The dielectric constant of the title compound as a function of temperature indicates that the permittivity is basically temperature-independent (dielectric constant equaling to 3.6 to 4.7), suggesting that this compound should not be ferroelectric or there may be no distinct phase transition within the measured temperature range. Similarly, below the melting point (453 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 3.6 to 4.7). Herein, we report the synthesis and crystal structure of the title compound.
The molecular structure of the title compund is presented in Fig. 1. The bond lengths and angles are within their normal ranges (Wishkerman & Bernstein, 2006). The cations and anions are connected via intermolecular N-H···F and C-H···F hydrogen bonds, forming a three dimensional network (Tab. 1 & Fig. 2).

Experimental
A mixture of aminoacetonitrile hydrochloride (0.095 g, 0.01 mol) and tetrafluoro-borate sodium (1.10 g, 0.01 mol) in water (20 ml) was stirred until clear. After several days, colourless prismatic crystals of the title compound were formed which were suitable for X-ray analysis.

Refinement
The methylene 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). The H-atoms bonded to the N-atom were located from a difference map and were allowed to refine freely. Fig. 1. Perspective structure of the title compound, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level.  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 Rfactors(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.