Electric fields in fluorocyclohexanes and the magnitude of19F chemical shifts

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Abstract
The 19F high resolution N.M.R. spectra of the four compounds C6F11Cl, C6F11Br, C6F10Cl2 and C6F10Br2 have been recorded under identical conditions, and the chemical shifts obtained compared with those of the axial and equatorial nuclei in perfluorocyclohexane. It is shown that the magnitude of the chemical shift of 19F nuclei more than two bonds removed from the chlorine or bromine atoms can be accounted for satisfactorily in terms of intramolecular electric fields, provided that the structure of the molecules is that of an asymmetrically distorted chair form.