Ionic plastic phases in trimethylammonium trifluoroacetate studied by ¹H and ¹⁹F NMR spectroscopy, X-ray diffraction and thermal measurements

¹H and ¹⁹F NMR, differential scanning calorimetric and X-ray powder diffraction measurements were carried out in solid trimethylammonium trifluoroacetate, (CH₃)₃NHCOOCF₃. Two solid-solid phase transitions were observed at 307 and 330 K. The structures of the solid phases obtained above 330 K and between 307 and 330 K are CsCl-type cubic and tetragonal, respectively. In the two phases, both cations and anions perform self-diffusion and isotropic rotation. From the dynamic behaviour of the ions together with thermal data, both phases are assignable as ionic plastic phases.