Stereochemical dependence of substituent γ-effects in the 19 F NMR shielding constants

Abstract

The substituent α-, β-, and γ-effects of the elements of the second and third periods on ¹⁹ F NMR chemical shifts are evaluated including the establishment of stereochemical dependence of γ-effect, the latter particularly important in stereochemical studies of fluorine-containing compounds. Benchmark calculations performed for a series of 32 simple inorganic fluorine-containing molecules demonstrated a markedly good correlation between calculated and experimental fluorine chemical shifts characterized by a mean absolute error of 22.5 ppm in the range of about 900 ppm, which corresponds to a 2.5% error in the percentage terms.

Keywords: 19F NMR chemical shift; BHandHLYP functional; aug-pcSseg-3 and aug-cc-pV6Z basis sets; small fluorine containing compounds; substituent and stereochemical effects.