Nuclear magnetic resonance studies of the difluoride ion. Part 3.—Ammonium and substituted ammonium difluorides

The 19F free induction decays from the difluoride ion in the ammonium, phenylamine, 2- and 4-methylphenylamine salts have been fitted theoretically by a Fourier transform of the lineshape function. In all four compounds, the best fit is obtained for a centred difluoride ion with F … F = 2.34 A(motionally-corrected value of 2.28 A); in the phenylamine and methylphenylamine difluorides the maximum departure of the proton from the centred position is 0.05 A.