Spectra-Structure Correlations in Nuclear Spin Resonances of Fluorine-19

Correlations of 52 fluorine-containing groups with their chemical shifts were obtained and are tabulated. Variation in the chemical shift for each of the functional groups is a function of the number of different secondary environments of the group in the model compounds examined. The group least rigidly defined, the CF/sub 2/ = CF- group, has the largest spread. The various kinds cf substituents that can be added to CF was seen to affect greatly the position of the CF/sub 2/ =CF-group. The range of chemical shifts in the F/sup 19/ resonance spectra extends over 300 ppm on the scale. Lines attributed to the perfluoromethylene groups are centered at 50 ppm, and those attributed to CF groups are located in the region of 100 ppm. A decrease in the electronegativity results in a shift to high fields, whereas an increase in the electronegativity results in a shift to low fields. Changes in bonding properties through ring strain and unsaturation also affect the chemical shift. (P.C.H.)