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Influence of σ-hyperconjugative interactions on 13C substituent chemical shifts: experimental and theoretical study in 1-X,3-CH3-bicyclo[1.1.1]pentanes

✍ Scribed by Rubén H. Contreras; Angel L. Esteban; Ernesto Díez; Ernest W. Della; Ian J. Lochert

Publisher
John Wiley and Sons
Year
2004
Tongue
English
Weight
115 KB
Volume
42
Category
Article
ISSN
0749-1581

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✦ Synopsis

(13)C chemical shifts were measured for 18 1-X,3-CH(3)-bicyclo[1.1.1]pentanes and the corresponding (13)C substituent chemical shifts (SCSs) were compared with those measured previously for the corresponding 1-X-bicyclo[1.1.1]pentanes. DFT-B3LYP calculations of GIAO magnetic shielding constants and of natural bond orbitals were carried out in order to gain an insight into factors defining the observed differences in (13)C SCSs in both series. These differences are rationalized in terms of substituent effects on sigma-hyperconjugative interactions.

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