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A semi-empirical MO calculation of 13C chemical shifts—I: Alkanes

✍ Scribed by V. N. Solkan; V. M. Mamayev; N. M. Sergeyev; Yu. A. Ustynyuk

Publisher
John Wiley and Sons
Year
1971
Tongue
English
Weight
326 KB
Volume
3
Category
Article
ISSN
0749-1581

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✦ Synopsis

13C shielding constants have been calculated for a series of alkanes, methane to pentane. The quantities ud and 8 ' have been obtained, using an average excitation energy approximation and the extended Huckel MO wave functions in terms of the Pople method. The results fit the experimental data and the VB results of Grant et al. fairly well. The quantity od varies within a wide range for cxbon atoms of various degrees of substitution. Two conformations of the hydrocarbons studied have been calculated. The results show that the 13C chemical shifts may be used for conformational analysis.

EXPERIMENTAL 13C chemical shifts are known for various classes of organic compounds : alkanes,1,2 a r ~r n a t i c s , ~, ~ heterocycle^,^.^ etc. These shifts were also calculated by the

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