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Carbon‐13 NMR and PM3 Study on the Substituent Effect of 1‐Aryl‐3,3‐Difluoro‐2‐Halocyclopropenes
Author(s) -
Lee ChuanChen,
Yang YaJen,
Lin ShawTao,
Chen LiChun
Publication year - 2006
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.200600122
Subject(s) - chemistry , substituent , aryl , chemical shift , ring (chemistry) , resonance (particle physics) , spectral line , stereochemistry , nmr spectra database , carbon 13 nmr , medicinal chemistry , group (periodic table) , organic chemistry , alkyl , physics , particle physics , astronomy
The substituent‐induced chemical shifts (SCS) of C2 and C3 on the 13 C NMR spectra of 1‐aryl‐3,3‐difluoro‐2‐halocyclopropenes were studied. The correlation between SCS and Hammett constants shows that the tendency of effect by the substituents on the phenyl ring is BrC2(ρ = 4.66) > ClC2(ρ = 4.50) and ClC3(ρ = −1.63) > BrC3(ρ = −1.41). The DSP treatment further confirms the SCS of C2 and C3 are the main contribution of the resonance effect and field effect, respectively. Those results of the incremental shifts reveals that the gem ‐difluorocyclopropenyl bearing the phenyl group possesses a triple bond character, which is also observed in IR spectra with high n̈ C=C (1768–1945 cm −1 ).