Molecular motions in the hydration sphere of the F−ion in aqueous solution. (with some results for HF, HF2, and BF)

Abstract

AbstractExperimental results for the F19nuclear magnetic relaxation rate in aqueous solutions of NaF, KF, RbF and CsF as a function of the concentration are reported. Using these data together with the proton relaxation behaviour in the same solutions three models for the hydration sphere are discussed: A long‐lived rigid and non‐rigid hydration sphere and a short‐lived hydration sphere. Then, experimental results for the self‐diffusion coefficient of the F−ion in aqueous solution together with the corresponding H2O self‐diffusion coefficients are reported. The analysis of all these data yields the result that the F−hydration sphere is non‐rigid and probably fairly short‐lived. ThepH dependence of the F−relaxation is evaluated to give the reorientational correlation times of HF and HFand from the F relaxation in NaBF4solution we derive the reorientational correlation time of the BFion.