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'Nuclear quadrupole resonance' in keywords Facet   section ZfN Section A:Volume 047  [X]
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1992 (4)
1Author    G. Wulfsberg, K. Shadid, B. Farris, J. Monn, T. Bonner, J. Yanisch, Al WeissRequires cookie*
 Title    Dioxin Precursors: NQR Studies of Group 1 and Related 2,6-Dichlorophenolate and 2,4,6-Trichlorophenolate Salts  
 Abstract    The 81 Br and 35 C1 NQR spectra of anhydrous Group 1, tetraalkylammonium, and thallium(I) 2,6-dichlorophenolates, 2,4,6-trichlorophenolates, and 4-bromo-2,6-dichlorophenolates were searched for evidence of solid-state cation-organochlorine interactions that might, for example, be (in part) responsible for the difference in the thermal decomposition reactions of these salts (to give the supertoxic environmental pollutants, the polychlorinated dibenzodioxins) versus those of the corresponding Group 11 chlorophenolate complexes, which do not decompose to dioxins. For cations ranging in size from tetraethylammonium to potassium, the total range of 35 C1 NQR frequencies in 2,6-dichlorophenolate and 2,4,6-trichlorophenolate salts is only 1.401 MHz, which, although larger than the 0.7 MHz range likely in molecular chlorocarbons, is smaller than in individual chlorophenolates of copper(I) and silver(I) (up to 2.0 MHz). In sodium and thallium(I) 2,4,6-trichlorophenolates substantially large frequency shifts (ca. 2.0 MHz) occur, to higher frequen-cies for the para-chlorines and lower frequencies for the ortho-chlorines (Na only). These disappear even in closely related compounds and show a pattern that seems unrelated to the decomposition products of the chlorophenolates. 
  Reference    Z. Naturforsch. 47a, 153—159 (1992); received July 16 1991 
  Published    1992 
  Keywords    Chlorophenolates, Nuclear quadrupole resonance, Dioxin 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0153.pdf 
 Identifier    ZNA-1992-47a-0153 
 Volume    47 
2Author    Gary Wulfsberg, Debra Jackson, William Ilsley, Shi-Qi Dou, Alarich Weiss, John GagliardiRequires cookie*
 Title    Coordination of OrfÄö-Chlorines in Copper (I) and Silver (I) 2,6-Di-and 2,4,6-Trichlorophenolates Crystal Structure of (2,4,6 -Trichlorophenolato-O, CI) bis (triphenylphosphine) silver (I)  
 Abstract    The crystal structure of (Ph 3 P) 2 AgOC 6 H 2 Cl 3 (I) is reported along with the syntheses and 35 C1 and 63 Cu NQR spectra of I and several related silver (I) and copper (I) 2,6-di-and 2,4,6-trichlorophe-nolates containing phosphines, phosphites, and pyridine as co-ligands. I crystallizes in space group P2 Jc with a= 16.692(4) Ä, b= 17.942 (4) A, c= 12.857 (3) Ä, /? = 97.60 (1)°, F = 3816.68 Ä 3 , and Z = 4. The final R (F) = 0.0475 and R (W) = 0.0396. Ag is coordinated in a trigonal planar geometry by the P atoms of the two triphenylphosphine ligands and the O atom of the chlorophenolate; Ag is then capped by one ortho-chlorine of the trichlorophenolate ligand at a distance of 3.160 (2) Ä. In the 35 C1 NQR spectrum of this compound the two orf/io-chlorines of the trichlorophenolate ligand have a large frequency difference of 1.500 MHz, indicating that one ortho-chlorine is coordinated to the silver; 35 C1 NQR spectra of related complexes are also presented and discussed. The 35 C1 NQR frequency differences of coordinated and non-coordinated orr/io-chlorines in metal chlorophenolates correlate well with the metal-chlorine distances but not with the metal-chlorine-carbon bond angles. A different correlation is found for the silver complexes of dichloroalkanes; possible reasons for this are discussed. 
  Reference    Z. Naturforsch. 47a, 75—84 (1992); received July 15 1991 
  Published    1992 
  Keywords    Nuclear quadrupole resonance, Chlorophenolates, Crystal structure, Chlorocarbons as ligands, Silver(I) complexes 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0075.pdf 
 Identifier    ZNA-1992-47a-0075 
 Volume    47 
3Author    Keizo Horiuchi, Daiyu NakamuraRequires cookie*
 Title    Chlorine Nuclear Spin-Spin Relaxation Mechanism in Mg(H 2 0) 6 SnCl 6 as Studied by NQR and NMR Techniques  
 Abstract    The 35 C1 NQR spin-lattice relaxation time T1Q, spin-spin-relaxation time T2Q, and J H NMR spin-lattice relaxation time in the rotating frame T le in Mg(H20)6SnCl6 were measured as functions of temperature. Above room temperature T2q increased rapidly with increasing temperature, which can be explained by fluctuations of the local magnetic field at the chlorine nuclei due to cationic motions. From the T le experiments, these motions are found to be attributable to uniaxial and overall reorientations of [Mg(H20)6] 2+ ions with activation energies of 95 and 116 kJ mol -1 , respectively. Above ca. 350 K, T1Q decreased rapidly with increasing temperature, which indicates a reorientational motion of [SnCl6] 2-ions with an activation energy of 115 kJ mol -1 . 
  Reference    Z. Naturforsch. 47a, 277—282 (1992); received October 29 1991 
  Published    1992 
  Keywords    Complex compounds, Molecular dynamics, Nuclear relaxation, Nuclear quadrupole resonance, Nuclear magnetic resonance 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0277.pdf 
 Identifier    ZNA-1992-47a-0277 
 Volume    47 
4Author    Noriaki Okubo, Harutaka Sekiya, Chiaki Ishikawa, Yoshihito AbeRequires cookie*
 Title    Br Nuclear Quadrupole Relaxation in the High Temperature Modification of Niobium Pentabromide  
 Abstract    The spin-lattice relaxation time of 79 Br NQR has been measured between 4.2 K and room temperature. The result is compared with that of 35 C1 NQR in NbCl 5 . The origin of the relaxation is attributed to the quadrupolar interaction and the temperature dependence is explained by the Raman process. The Debye temperature is determined to be 94 K and the relaxation time is related with the NQR frequency through the covalency. 
  Reference    Z. Naturforsch. 47a, 713—720 (1992); received December 13 1991 
  Published    1992 
  Keywords    Niobium pentabromide, Nuclear quadrupole resonance, Spin-lattice relaxation, Raman process, Debye temperature 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0713.pdf 
 Identifier    ZNA-1992-47a-0713 
 Volume    47