STUDIES OF CHEMICAL SHIFT ANISOTROPY IN LIQUID-CRYSTAL SOLVENTS .2. THEORETICAL CALCULATIONS FOR METHYL HALIDES

被引:10
作者
CEASAR, GP
DAILEY, BP
机构
[1] Department of Chemistry, Columbia University, New York
关键词
D O I
10.1063/1.1670885
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
Experimentally determined values of the proton chemical-shift anisotropy for the methyl halides have been used to test simple phenomenological theories which have been proposed to account for proton magnetic shielding. It is shown that the frequently used magnetic dipole model predicts that the long-range contribution to the proton shielding anisotropy should largely depend on the average neighbor magnetic susceptibility. Anisotropies calculated from this model are much larger than those measured. Expressions have also been derived relating the proton shielding anisotropy to the electric dipole moment and charge densities of polar substituants. Results of these calculations are not as conclusive as in the magnetic dipole case.
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页码:4200 / &
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