Gauche Preference of β‑Fluoroalkyl Ammonium Salts

Abstract

The strong gauche preference along with the F–C–C–N⁺ fragment in 3-fluoropiperidinium cation and analogues, in the gas phase, is dictated by electrostatic interactions, which can be both hydrogen bond F···H­(N⁺) and F/N⁺ attraction. In aqueous solution, where most biochemical processes take place, electrostatic effects are strongly attenuated and hyperconjugation is calculated to be at least competitive with Lewis-type interactions