13C13C coupling constants and substituent effects on13C chemical shifts in13C labelled pyrene and pyrene derivatives

1975 ◽  
Vol 7 (1) ◽  
pp. 23-25 ◽  
Author(s):  
P. E. Hansen ◽  
O. K. Poulsen ◽  
A. Berg
Keyword(s):  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Pyrene Derivatives

Carbon magnetic resonance studies of some phenyl, furyl and thienyl organometallics. Some comments on carbon-metal scalar coupling

1974 ◽  
Vol 27 (2) ◽  
pp. 417 ◽  
Author(s):  
D Doddrell ◽  
KG Lewis ◽  
CE Mulquiney ◽  
W Adcock ◽  
W Kitching ◽  
...  
Keyword(s):  
Chemical Shift ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Scalar Coupling ◽  
Coupling Constant ◽  
Aryl Substituent ◽  
Magnetic Resonance Studies ◽  
Thienyl Group ◽  
13C Chemical Shift

13C chemical shift variations within a series of phenyl, furyl and thienyl Group IVB organometallics appear to be best understood in terms of the usual alkyl and aryl substituent effects on 13C chemical shifts and not variations in dπ ?pπ metal-aryl interactions. Large changes in 13C-metal scalar coupling constants have been observed suggesting that other factors besides the s-character of the carbon-metal bond is responsible in determining the coupling constant.

Etudes d'hétérocycles pentagonaux polyhétéroatomiques par résonance magnétique nucléaire du 13C. Thiazoles et thiazolo[2,3-e]tétrazoles

1978 ◽  
Vol 56 (1) ◽  
pp. 46-55 ◽  
Author(s):  
Robert Faure ◽  
Jean-Pierre Galy ◽  
Emile-Jean Vincent ◽  
José Elguero
Keyword(s):  
Electronic Structure ◽  
Comparative Study ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Thiazole Ring ◽  
Résonance Magnétique

Carbon-13 nmr spectra of 18 thiazoles with different substituents (R = CH3, C6H5, Cl, Br, NH2 et N3) have been recorded. The 13C chemical shifts and the nJ(C,H) coupling constants are discussed as a function of the nature of the substituent and the electronic structure of the thiazole ring. The 2-azido substituted thiazoles show azido-tetrazole isomerism, making possible a comparative study of substituent effects in thiazole and thiazolotetrazole rings. These studies have been extended to other heterocycles: benzothiazole, isothiazole, and isoxazole.

Substituent effects on geminal proton–proton coupling constants

1970 ◽  
Vol 48 (13) ◽  
pp. 2134-2138 ◽  
Author(s):  
Y. L. Chow ◽  
S. Black ◽  
J. E. Blier ◽  
M. M. Tracey
Keyword(s):  
Carbon Tetrachloride ◽  
Chemical Shifts ◽  
Substituent Effects ◽  
Coupling Constants ◽  
Proton Proton ◽  
Proton Coupling ◽  
Geminal Proton ◽  
Geminal Coupling ◽  
Hammett Σ Constants

The geminal coupling constants between the non-equivalent benzylic protons of a series of para- and meta-substituted N-benzyl-2-methylpiperidines were shown to be proportional to the Hammett σ constants of the substituents with ρ −1.38 in carbon tetrachloride, −1.21 in benzene, and nearly 0 in 1 N DCl solutions. The ρ values were compared with those of other series and were discussed in terms of the possible conformations involved. The chemical shifts of the benzylic protons of the piperidine derivatives did not give a good correlation with the Hammett σ constants in these solvents.

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