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Interpretation of substituent‐induced chemical shifts in 13 C NMR spectra of 2‐substituted norbornadienes. Influence of homoconjugation
Author(s) -
Krawczyk Hanna,
Szatylowicz Halina,
GryffKeller Adam
Publication year - 1995
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260330506
Subject(s) - chemistry , substituent , chemical shift , spectral line , nmr spectra database , resonance (particle physics) , computational chemistry , interpretation (philosophy) , carbon 13 nmr , bicyclic molecule , stereochemistry , crystallography , physics , particle physics , astronomy , computer science , programming language
Complete signal assignments and an interpretation of the 13 C NMR spectra of bicyclo[2.2.1]hepta‐2,5‐diene and of 12 of its 2‐substituted derivatives are presented. The substituent effects observed at C‐1, C‐2 and C‐3 are very similar to those reported for 2‐substituted propenes and monosubstituted benzenes. Transmission of those effects on C‐5 and C‐6 may be at least partially attributed to the homoconjugative interaction between the double bonds in the systems investigated. The relative importance of the field and the resonance effects at particular positions have been evaluated by the dual substituent parameter analysis of the chemical shift data. Relationships between substituent‐induced chemical shifts and electron densities, calculated by the PM3 method, have been found.