Solvation of sodium ions studied by 23Na nuclear magnetic resonance

Abstract

The 23Na chemical shifts, extrapolated to infinite dilution, of solutions containing sodium iodide dissolved in 14 different oxygen or nitrogen donor organic solvents have been determined. The observed range of chemical shifts can be successfully related to changes in the paramagnetic term of the general nuclear screening equation. A fair correlation between the magnitude of the paramagnetic term and the Lewis basicity of the solvent has been drawn. Those solvents showing anomalous behavior are the ones for which large magnetic anisotropies are to be expected. The 23Na chemical shifts for two mixed solvent systems containing sodium iodide have been obtained, and these support the conclusion that preferential solvation of the sodium ion occurs.