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Titolo:
H-1 AND F-19 NMR-STUDIES ON MOLECULAR MOTIONS AND PHASE-TRANSITIONS IN SOLID TRIETHYLAMMONIUM TETRAFLUOROBORATE
Autore:
ONO H; SEKI R; IKEDA R; ISHIDA H;
Indirizzi:
OKAYAMA UNIV,COLL GEN EDUC,DEPT CHEM OKAYAMA 700 JAPAN OKAYAMA UNIV,COLL GEN EDUC,DEPT CHEM OKAYAMA 700 JAPAN UNIV TSUKUBA,DEPT CHEM TSUKUBA IBARAKI 305 JAPAN
Titolo Testata:
Journal of molecular structure
, volume: 345, anno: 1995,
pagine: 235 - 243
SICI:
0022-2860(1995)345:<235:HAFNOM>2.0.ZU;2-2
Fonte:
ISI
Lingua:
ENG
Soggetto:
IONIC PLASTIC PHASE; THERMAL MEASUREMENTS; MAGNETIC-RESONANCE; METHYLAMMONIUM; RELAXATION; CHLORIDES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
21
Recensione:
Indirizzi per estratti:
Citazione:
H. Ono et al., "H-1 AND F-19 NMR-STUDIES ON MOLECULAR MOTIONS AND PHASE-TRANSITIONS IN SOLID TRIETHYLAMMONIUM TETRAFLUOROBORATE", Journal of molecular structure, 345, 1995, pp. 235-243

Abstract

Measurements by differential thermal analysis and differential scanning calorimetry and of the spin-lattice relaxation time (T-1), the spin-spin relaxation time (T-2), and the second moment (M(2)) of H-1 and F-19 NMR were carried out in the three solid phases of (CH3CH2)(3)NHBF4. X-ray powder patterns were taken in the highest-temperature phase (Phase I) existing above 367 K and the room-temperature phase (Phase II)stable between 220 and 367 K. Phase I formed a NaCl-type cubic structure with a = 11.65(3) Angstrom, Z = 4, V = 1581(13) Angstrom(3), and D-x = 0.794 g cm(-3), and was expected to be an ionic plastic phase. Inthis phase, the self-diffusion of anions and the isotropic reorientation of cations were observed. Phase II formed a tetragonal structure with a = 12.47(1) and c = 9.47(3) Angstrom, Z = 4, V = 1473(6) Angstrom(3), and D-x = 0.852 g cm(-3). From the present DSC and NMR results inthis phase, the cations and/or anions were considered to be dynamically disordered states. The C-3' reorientation of the cation about the N-H bond axis was detected and, in addition, the onset of nutation of the cations and local diffusion of the anions was suggested. In the low-temperature phase (Phase III) stable below 219 K, the C-3 reorientations of the three methyl groups of cations and the isotropic reorientation of anions were observed. The motional parameters for these modes were evaluated.

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Documento generato il 23/09/20 alle ore 09:05:18