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'Molecular motion' in keywords Facet   section ZfN Section A  [X]
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2000[X]
1Author    Takahiro Ueda, Nobuo NakamuraRequires cookie*
 Title    Nature of Hydration Water in (±)-Tris(ethylenediamine)cobalt(III) Chloride Hydrate, (±)-[Co(en) 3 ]Cl 3 -/iH 2 0, as Studied by *H, 2 H, and 17 O Solid State NMR  
 Abstract    The static and dynamics properties of hydration water molecules in (±)-[Co(en) 3 ]Cl 3 were studied by means of 'H, 2 H, and ,7 0 solid state NMR. By 'H pulsed field gradient (PFG) NMR the apparent diffusion coefficient of mobile water through a micropore along the crystalline unique c-axis was found to be 1.0 x 10~ 9 m 2 s -1 . The 2 H NMR spectrum at 141 K consists of two components, one being a Pake doublet corresponding to a quadrupole coupling constant (QCC) of (226 ± 2) kHz and an asymmetry parameter of the electric field gradient 77 of 0.08 ± 0.01, and another being a Gaussian line with a linewidth of 3.5 kHz. The 17 0 NMR spectrum at 300 K also consists of a narrow Gaussian peak and a broad powder pattern with a second order quadrupole effect corresponding to QCC = (6.3 ± 0.5) MHz and 77 = 0.55±0.02. The broad and narrow components are assigned to water molecules accommodated at general 12g positions and special 2a and 2b positions in the trigonal lattice with space group Plcl. From the ratio of the populations at these positions their potential energy difference was estimated to be between (2.7 ±0.1) and (3.5 ± 0.1) kJmol -1 . The 2 H NMR spectrum at room temperature indicates a finite quadrupole interaction which is attributable to the rapid rotation of water molecule about the molecular C 2 -axis. When the water content exceeds 2.7, the QCC is reduced sharply to (5.0 ±0.1) kHz at 285 K, suggesting that there occurs rapid rotation of water and rapid exchange of 2 H between nonequivalent positions. 
  Reference    Z. Naturforsch. 55a, 362—368 (2000); received August 23 1999 
  Published    2000 
  Keywords    (±)-[Co(en) 3 ]Cl 3, Absorbed Water, Molecular Motion, Hydrogen Bond, Quadrupole Interaction 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0362.pdf 
 Identifier    ZNA-2000-55a-0362 
 Volume    55 
2Author    Hiroyuki IshidaRequires cookie*
 Title    H NMR Study of Ionic Motions in High Temperature Solid Phases of (CH 3 NH 3 ) 2 ZnCl 4  
 Abstract    The reorientation of the tetrahedral complex anion ZnCl 4 2-and the self-diffusion of the cation in (CH 3 NH3) 2 ZnCl4 were studied by 'H NMR spin-lattice relaxation time ('H T X) experiments. In the second highest-temperature phase, the temperature dependence of *H T X observed at 8.5 MHz could be explained by a magnetic dipolar-electric quadrupolar cross relaxation between 'H and chlorine nuclei, and the activation energy of the anion motion was determined to be 105 kJ mol -1 . In the highest-temperature phase, the activation energy of the self-diffusion of the cation was determined to be 58 kJ mol -1 from the temperature and frequency dependence of 'H T X . 
  Reference    Z. Naturforsch. 55a, 412—114 (2000); received January 8 2000 
  Published    2000 
  Keywords    Nuclear Magnetic Resonance, Molecular Motion, Cross Relaxation, (C^N^^ZnCfj 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0412.pdf 
 Identifier    ZNA-2000-55a-0412 
 Volume    55