Isopropylammonium tetrafluorohydrogenphthalate: Structural characterization and comparison to two related salts with different stoichiometric ratios

The normal acid salt isopropylammonium tetrafluorohydrogenphthalate (3) was prepared and its structure was determined by X-ray crystallography. This salt is stabilized by N-H…O, O-H…O, C-H…O, and N-H…F hydrogen bonds. Compound 3 was characterized by means of solution and solid-state NMR. The ipso-carbons, whose signals are equivalent in solution, could be distinguished in the solid state, thus reflecting the asymmetric nature of 3. With respect to structural features, 3 was compared with salts of different stoichiometry, i.e. the neutral salt bis(isopropylammonium) tetrafluorophthalate (1) and the anomalous salt isopropylammonium tetrafluorohydrogenphthalate × tetrafluorophthalic acid (2).