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'35 C1 NQR' in keywords
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2000 (1)
1996 (1)
1992 (1)
1Author    35, J. N. Latosińska, J. KasprzakRequires cookie*
 Title    Solid State Effects in 4,6-Dichloropyrimidine Studied by Cl-NQR Spectroscopy and ab initio Calculations  
 Abstract    Quantum chemistry methods -ab initio -have been used for the assignment of the 35 C1-NQR resonance frequencies to particular chlorine atoms substituted in positions 4 and 6 of pyrimidine. The so-called solid state effect, that is the influence of intermolecular interactions, in particular hydrogen bond formation, on the NQR parameters has also been studied. 
  Reference    Z. Naturforsch. 55a, 343—347 (2000); received August 28 1999 
  Published    2000 
  Keywords    35 C1-NQR, 4,6-Dichloropyrimidine, Electronic Structure, B3LYP/6-31G* 
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 TEI-XML for    default:Reihe_A/55/ZNA-2000-55a-0343.pdf 
 Identifier    ZNA-2000-55a-0343 
 Volume    55 
2Author    Hirokazu Nakayama, Taro Eguchi, Michihiko KishitaRequires cookie*
 Title    Phase Transitions in Bis(4-chlorophenyl)sulfone as Studied by 35 C1 FT-NQR  
 Abstract    The temperature dependence of 35 C1 NQR frequencies in bis(4-chlorophenyl)sulfone was mea-sured in the temperature range of 4.2-297 K. Below 115 K four NQR lines due to four inequivalent chlorines exist in the commensurate phase, contrary to the single NQR line reported by Corbero et al. It follows that the commensurate-incommensurate transition is of the first-order, and the incommensurate-normal transition at 150 K is quasi-continuous. It is also suggested that the succes-sive phase transitions are triggered by the small angle rotation of the molecules about their C2-axes. 
  Reference    Z. Naturforsch. 47a, 232—236 (1992); received July 10 1991 
  Published    1992 
  Keywords    35 C1 NQR, Bis(4-chlorophenyl)sulfone, 'H NMR, Incommensurate phase, Phase tran-sition 
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 TEI-XML for    default:Reihe_A/47/ZNA-1992-47a-0232.pdf 
 Identifier    ZNA-1992-47a-0232 
 Volume    47 
3Author    Serge David, Michel Gourdji, Lucien Guibé, Alain PéneauRequires cookie*
 Title    Chlorine Substituted Acetic Acids and Salts. Effect of Salification on Chlorine-35 NQR  
 Abstract    The NQR of a quadrupolar probe nucleus is often used to investigate the effect of substituent in molecules. The inductive effect, based on a partial charge migration along the molecular skeleton is the only one present in saturated aliphatics, the conjugative effect appearing in conjugated molecules, especially aromatics. As the stepwise charge migration mechanism, formerly used to explain the inductive effect, is now believed obsolete, we have wanted to reexamined the case of chlorine substituted acetic acids and salts. The data in literature was extended by observing reso-nances and determining NQR frequencies in several acids and salts. The present analysis of the salification of mono-, di-and tri-chloroacetic acids, which is equivalent to a deprotonation or the substitution of the acid hydrogen by a negative unit charge, shows that a model based on the polarization of the chlorine atom(s) by the carboxyle group is consistent with experimental results: the polarization energy appears to be proportional to the NQR frequency shifts; experimental data show a correlation between the NQR frequency shifts accompanying salification and the variations of the intrinsic acidity measured in the gas phase; this, in turn shows that there is a proportionality between the polarization energy and the variations in the acid free enthalpy of dissociation. From the comparison between fluorine, chlorine, bromine and iodine, it also appears that an alternative mechanism, the polarization of the carboxyl group by the halogen, would be important only in the case of the fluoroacetic acid. 
  Reference    Z. Naturforsch. 51a, 611—619 (1996); received October 10 1995 
  Published    1996 
  Keywords    35 C1 NQR, Chloroacetic acids, Substituent effect, Inductive effect, Polarization, Intrin-sic acidity 
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 TEI-XML for    default:Reihe_A/51/ZNA-1996-51a-0611.pdf 
 Identifier    ZNA-1996-51a-0611 
 Volume    51