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Solutions of alkali metal fluorides in aliphatic diols or carboxylic acids have been investigated by 19F n.m.r. at concentrations of ca. 0.5 mol kg–1 and greater. Heats of association of potassium fluoride with ethane-1,2-diol and methanoic acid are obtained from variable-temperature n.m.r. studies. The nature of the strong hydrogen bond and its influence on the n.m.r. spectra are discussed.

Heavy alkali-metal fluorides are soluble in low-molecular-weight liquid aliphatic diols. Low-field shifts in the proton magnetic resonances of selected fluoride–diol solutions may be interpreted as being due largely to strong hydrogen bonding between the fluoride anion and the diol hydroxyls, although cation effects are also evident. Variable-temperature 1H n.m.r. studies on KF–1,2-ethanediol, CH3CN–1,2-ethanediol, and neat 1,2-ethanediol have been carried out and values of –(50 ± 10) kJ mol–1 for ΔH⊖ and –(130 ± 25) J K–1 mol–1 for ΔS⊖ have been determined for the (F ⋯ HO)– hydrogen bond.

Heavy alkali-metal fluorides are soluble in low-molecular-weight liquid aliphatic diols. Low-field shifts in the proton magnetic resonances of selected fluoride–diol solutions may be interpreted as being due largely to strong hydrogen bonding between the fluoride anion and the diol hydroxyls, although cation effects are also evident. Variable-temperature 1H n.m.r. studies on KF–1,2-ethanediol, CH3CN–1,2-ethanediol, and neat 1,2-ethanediol have been carried out and values of –(50 ± 10) kJ mol–1 for ΔH⊖ and –(130 ± 25) J K–1 mol–1 for ΔS⊖ have been determined for the (F ⋯ HO)– hydrogen bond.