NMR study of the FH⋯F hydrogen bond. Relation between hydrogen atom position and FH⋯F bond length Original Research Article

1H and 19F NMR study of (NH4)3BiBr6NH4Br·2NH4HF2 shows the bifluoride ion in this compound to be asymmetric with distances r(HF) = 1.042 ± 0.002 and R(FF) = 2.373 ± 0.008 Å. Existing NMR and neutron diffraction data for the FH⋯F hydrogen bond in solids have been studied to find a relation between the position of the hydrogen atom and FH⋯F bond length. Such a relation has been established and explained in the framework of the two-dimensional dynamic model of the hydrogen bond. The dependencies of r(AH) on R(AB) for the OH⋯O and FH⋯F bonds are shown to be similar.