STABLE CARBOCATIONS .277. C-13 AND F-19 NMR SPECTROSCOPIC STUDY OF SUBSTITUENT EFFECTS IN A,A-DIFLUOROARYLCARBENIUM IONS

In a series of α,α-difluoroarylcarbenium ions 1, one bond 13C-19F coupling constants and the 19F chemical shifts at the cationic center have been used as criteria to follow the extent of fluorine non-bonded electron pair back donation. The electron demand at the cationic center was systematically altered by changing the nature of the substituents on the aryl ring and substituent effects were studied by 13C and 19F NMR spectroscopy. © 1990.