Preparation, 13C NMR and IGLO/DFT Studies of Trifluoromethyl Substituted Allyl Cations
α-Trifluoromethyl substituted allyl cations 3 and 4 have been prepared by ionizing their corresponding alcohols with SbF5 in SO2CIF at low temperatures. The barriers to rotation around the C1-C2 bond of the both cations were determined to be about 9 kcal/mol. The unusually low barriers as compared with their methyl analogues are rationalized by the unsymmetrical nature of the cations. CF3-substituted cyclohexenyl cations 8 and 10 were also prepared and characterized by 13C NMR spectroscopy. Density functional theory (DFT) calculations were performed to investigate geometries and charge densities of tifluoromethyl substituted allyl cations. 13C NMR chemical shifts of the cations were also calculated by IGLO method and compared with the experimental results.
G. K. Prakash et al., "Preparation, 13C NMR and IGLO/DFT Studies of Trifluoromethyl Substituted Allyl Cations," Research on Chemical Intermediates, Springer Verlag, Aug 1996.
The definitive version is available at http://dx.doi.org/10.1163/156856796X00278
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