Ionic motions and phase transitions in solid trimethylethylammonium tetrafluroberate studied by by1H, 19F, and14N NMR, powder X-ray diffraction and differential scanning calorimetry

Hiroshi Ono, Ryuichi Ikeda, Hiroyukl Ishida

Research output: Contribution to journalArticlepeer-review

14 Citations (Scopus)

Abstract

1H, 19F, and 14N NMR, powder X-ray diffraction, and differential scanning calorimetry (DSC) were studied for trimethylethylammonium tetrafluoroborate, (CH3)3NC2H5BF4. Five solid phases, named I, II, III, IV, and V in the order of decreasing temperature, were obtained in the temperature range 77-630 K. The transition temperatures and the corresponding enthalpy changes determined by DSC were 222K (0.16kj moi-1), 239K (1.8 kJ mol-1), 293 K (2.1 kJ mol-1), and 362 K (4.5 kJ mol-1). X-ray powder patterns showed that Phase I and II form an NaCl-type cubic lattice (a = 10.14 Å, Z = 4) and a tetragonal lattice (a = 8.59, c = 6,24 Å, Z = 2), respectively. The NMR study revealed that the canonic orientation in Phase I and II is dynamically disordered. Moreover, since the self-diffusion of anions and the Isotropie rotation of cations were observed in Phase I, this phase can be considered as a mesophase very close to the plastic phase. In Phases II, III, IV, and V we have detected the isotropic reorientation of anions, the anisotropic tumbling of cations, the C′3 reorientation of the whoie (CH3)3N group about C-N bond axis, and the C3 reorientation of the CH3 groups. The motional parameters were evaluated for these cationic and anionic motions.

Original languageEnglish
Pages (from-to)1833-1838
Number of pages6
JournalBerichte der Bunsengesellschaft/Physical Chemistry Chemical Physics
Volume100
Issue number11
Publication statusPublished - Dec 1 1996
Externally publishedYes

Keywords

  • Crystal structure
  • Diffusion
  • Nuclear magnetic resonance
  • Phase transitions
  • Speciroscopy

ASJC Scopus subject areas

  • Chemical Engineering(all)

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