Analysis of the total ion–solvent encounter configurations of CIO –4 and BF –4 with Na+ and Li+ in water, studied by various nuclear magnetic relaxation times

Abstract

From ¹⁹F magnetic relaxation rates caused by nuclear magnetic dipole–dipole interaction with ¹⁷OD₂ and ¹⁶OH₂, the orientation of water molecules in the hydration sphere of the structure breaking ion BF^–₄ is determined. We find the radial orientation of the electric dipole moment to be very likely at high dilution, though at higher concentration marked deviations from this orientation do occur. From ¹⁹F–⁷Li magnetic interaction a cation–anion model distribution function was obtained; ⁷Li–H₂O interactions lead to information on the hydration structure of Li⁺. ⁷Li and ²³Na relaxation together with ³⁵Cl and ¹¹B relaxation, all caused by electric quadrupole interaction, within the electrostatic model theory, yield a particular electric dipole orientation for the three water molecules belonging simultaneously to the cationic and anionic hydration sphere during the process of ion encounter.