Abstract: ~(23)Na~+ chemical shift of NaClO_4 in mixed solvents of water-aceton,water-ace- tonitrile, and water-ethanol and of NaBPh_4 in methanol-DMF,methanol-ben- zene, and methanol-dioxane were measured.By means of iso-solvation point the solvating abilities were compared as water>aceton≥acetonitrile≥ethanol and DMF>methanol. The preferential solvation free energies of Na~+ for the pairs of solvents, methanol-DMFand water-aceton,were evaluated as -2.7 kJ mol~(-1) for DMF to methanol and 4.6 kJ mol~(-1) for aceton to water.
~(23)Na~+ chemical shift in methanol-benzene is independent of the content of benzene. It verifies the simple solvation modle for ion in methanol-inert solvent mixture. However the chemical shift of ~(23)Na~+ in methanol-dioxane mixture varies with the composition of solvent. The inewidth of Na-23 resonance peak increases dramtically with the increasing of dioxane. It seems that the dioxane molecules disturb the primary solvation shell of Na~+ in methanol and result a unsymmetrical immediate surrounding for Na~+ cation.