TY - JOUR
T1 - Self-Diffusion and Reorientation of Methylammonium Ions in (CH3NH3)2ZnCl4Crystals as Studied by 1H-NMR
AU - Ishida, Hiroyuki
AU - Iwachido, Tadashi
AU - Hayama, Naomi
AU - Ikeda, Ryuichi
AU - Terashima, Mifune
AU - Nakamura, Daiyu
N1 - Funding Information:
(CH3)nNH4_„X (n = 0,1, 2, 3: X = N 03, C104.1) and (CH3NH3)2S04 [16, 23-30], In some of these salts, it has been confirmed by NMR, X-ray and DSC measurements that these phases can be considered as ionic plastic phases similar to the plastic crystals of molecular compounds [16, 23-27], For example, methylammonium nitrate was shown to form CsCl-type cubic crystals in this phase, and small AS{(12 J K~1m o f1) and large JStr (28 J K_1 mol-1) were observed [26], For (CH3NH3)2ZnCl4, however, zJ5f(36 J K~1mol"1) is much larger than zlStr (20J K.-1 moP1). This is probably because the [ZnCl4]2-ions are not free enough to reorient even in the high-temperature phase. Similar results, zlSf (43 J K-1 mol-1) and zlStr (26 J K "1m o f1), were also observed for (CH3NH3)2-S04 in our preliminary DSC measurements. Thus there seem to exist remarkable differences in the plastic nature between methylammonium salts with divalent anions and those with monovalent anions. We thank Mr. T. Masuda of the Instrument Development Center of the Faculty of Science, Nagoya University for constructing the RF probe head for the *H NMR measurements at the Larmor frequency 32 MHz and Mr. T. Nöda in the Department of Chemistry, Nagoya University for making a glass Dewar system to measure Txat various temperatures. We are also thankful to Dr. K. Horiuchi, University of Ryukyus for his help in constructing the pulse programmer. This work was partly supported by a research grant from the Iwatani Naoji Foundation and the Joint Studies Program (1988-1989) of the Institute for Molecular Science.
PY - 1989/8/1
Y1 - 1989/8/1
N2 - Differential thermal analysis, differential scanning calorimetry, and measurements of the 1H spin-lattice relaxation times and second moments of 1H-NMR absorptions were performed on methylammonium tetrachlorozincate(II) crystals over a wide temperature range. A solid-solid phase transition was located at 477 K. From the 1H-NMR experiments it was found that the cations undergo overall reorientation as well as three dimensional translational self-diffusion in the high-temperature phase. In the low-temperature phase, a 120 reorientational motion of the CH3 and NH3+groups of the cation about its C - N bond axis was detected. The parameters for the motional modes of the cations in the crystal were evaluated from the analysis of the 1H-NMR experimental results.
AB - Differential thermal analysis, differential scanning calorimetry, and measurements of the 1H spin-lattice relaxation times and second moments of 1H-NMR absorptions were performed on methylammonium tetrachlorozincate(II) crystals over a wide temperature range. A solid-solid phase transition was located at 477 K. From the 1H-NMR experiments it was found that the cations undergo overall reorientation as well as three dimensional translational self-diffusion in the high-temperature phase. In the low-temperature phase, a 120 reorientational motion of the CH3 and NH3+groups of the cation about its C - N bond axis was detected. The parameters for the motional modes of the cations in the crystal were evaluated from the analysis of the 1H-NMR experimental results.
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U2 - 10.1515/zna-1989-0811
DO - 10.1515/zna-1989-0811
M3 - Article
AN - SCOPUS:84961472932
VL - 44
SP - 741
EP - 746
JO - Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences
JF - Zeitschrift fur Naturforschung - Section A Journal of Physical Sciences
SN - 0932-0784
IS - 8
ER -