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Titolo:
IONIC MOTIONS AND PHASE-TRANSITIONS IN SOLID TRIMETHYLETHYLAMMONIUM TETRAFLUOROBORATE STUDIED BY H-1, F-19, AND N-14 NMR, POWDER X-RAY-DIFFRACTION, AND DIFFERENTIAL SCANNING CALORIMETRY
Autore:
ONO H; IKEDA R; ISHIDA H;
Indirizzi:
OKAYAMA UNIV,FAC SCI,DEPT CHEM OKAYAMA 700 JAPAN OKAYAMA UNIV,FAC SCI,DEPT CHEM OKAYAMA 700 JAPAN UNIV TSUKUBA,DEPT CHEM TSUKUBA IBARAKI 305 JAPAN
Titolo Testata:
Berichte der Bunsengesellschaft fur Physikalische Chemie
fascicolo: 11, volume: 100, anno: 1996,
pagine: 1833 - 1838
SICI:
0005-9021(1996)100:11<1833:IMAPIS>2.0.ZU;2-Z
Fonte:
ISI
Lingua:
ENG
Soggetto:
PLASTIC PHASE; THERMAL MEASUREMENTS; MOLECULAR MOTIONS; SELF-DIFFUSION; H-1-NMR;
Keywords:
CRYSTAL STRUCTURE; DIFFUSION; PHASE TRANSITIONS; SPECTROSCOPY, NUCLEAR MAGNETIC RESONANCE;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
24
Recensione:
Indirizzi per estratti:
Citazione:
H. Ono et al., "IONIC MOTIONS AND PHASE-TRANSITIONS IN SOLID TRIMETHYLETHYLAMMONIUM TETRAFLUOROBORATE STUDIED BY H-1, F-19, AND N-14 NMR, POWDER X-RAY-DIFFRACTION, AND DIFFERENTIAL SCANNING CALORIMETRY", Berichte der Bunsengesellschaft fur Physikalische Chemie, 100(11), 1996, pp. 1833-1838

Abstract

H-1, (19)E and N-14 NMR, powder X-ray diffraction, and differential scanning calorimetry (DSC) were studied for trimethylethylammonium tetrafluoroborate, (CH3)(3)NC2H5BF4. Five solid phases, named I, II, III, IV, and V in the order of decreasing temperature, were obtained in thetemperature range 77 - 630 K. The transition temperatures and the corresponding enthalpy changes determined by DSC were 222 K (0.16 kJ mol(-1)), 239 K (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 (n = 10.14 Angstrom, Z = 4) and a tetragonal lattice (a = 8.59, c = 6.24 Angstrom, Z = 2), respectively. The NMR study revealed that the cationic orientation in Phase I and II is dynamically disordered. Moreover, since the self-diffusion of anions and the isotropic 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 whole (CH3)(3)N group about C-N bond axis, and the C-3 reorientation of the CH3 groups. The motional parameters were evaluated for thesecationic and anionic motions.

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Documento generato il 30/09/20 alle ore 10:28:27