NON-EMPIRICAL AND DFT CALCULATIONS OF 19F AND 13C CHEMICAL SHIFTS IN THE NMR SPECTRA OF SUBSTITUTED PENTAFLUOROBENZENES
D. S. Fadeev, I. P. Chuikov, V. I. Mamatyuk
N. N. Vorozhtsov Institute of Organic Chemistry, Siberian Division, Russian Academy of Sciences
Keywords: pentafluorobenzene, NMR, quantum chemical calculation, heptafluorobenzyl cation
Abstract
Chemical shifts in 19F and 13C NMR spectra of substituted pentafluorobenzenes are calculated by Hartree-Fock and density functional theory methods. The calculated values are compared with the experimental data known from the literature. It is shown that chemical shifts in non-polar solvents can be predicted sufficiently accurately by the GIAO-DFT(PBE/L22) method. This method is used to predict the 19F and 13C chemical shifts of a heptafluorobenzyl cation in the SbF5 medium. The best agreement between the calculated and experimental values is achieved when the counterion effect is taken into account.
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