Tris(hydroxymethyl)methanaminium trifluoroacetate

In the crystal structure of the title salt, C4H12NO3 +·C2F3O2 −, N—H⋯O and O—H⋯O hydrogen bonds link the ions, forming a complex three-dimensional network.

In the crystal structure of the title salt, C 4 H 12 NO 3 + ÁC 2 F 3 O 2 À , N-HÁ Á ÁO and O-HÁ Á ÁO hydrogen bonds link the ions, forming a complex three-dimensional network.

Comment
Recently much attention has been devoted to crystals containing organic ions and inorganic ions due to the possibility of tuning their special structural features and their potential ferroelectrics properties (Fu et al., 2011;Zhang et al., 2010.).
The compound (C 4 H 12 O 3 N) + (C 2 F 3 O 2 )has an asymmetric unit that consists of one tris(hydroxymethyl)methanaminium cation and one trifluoroacetate anion (Fig 1). N-H···O and O-H···O hydrogen bonds form a complex three-dimensional network, (Fig 2). The trifluoromethyl group is quite mobile, but examination of a difference map in the plane of the fluorine atoms does show that the fluorine atoms exist as three distinct atoms.
Experimental 1.21 g (0.01 mol) of tris(hydroxymethyl)methanaminium was firstly dissolved in 30 ml of ethanol, to which 1.14 g (0.01 mol) of trifluoroacetic acid was added at the ambient temperature. Single crystals suitable for X-ray structure analysis were obtained by the slow evaporation of the above solution after 3 days in air.
The dielectric constant of the compound as a function of temperature indicates that the permittivity is basically temperature-independent (ε = C/(T-T 0 )), suggesting that this compound is not ferroelectric or that there may be no distinct phase transition occurring within the measured temperatur (below the melting point).

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.