Abstract: ~(23)Na~+ chemical shift of NaClO_4 in mixed solvents of water-acetone,water- acetonitrile, and water-ethanol and of NaBPh_4 in methanol-DMF, methanol-benzene, and methanol-dioxane were measured. By means of iso-solvation point the sol- rating abilities were compared as water>acetone≥acetonitile≥ethanol and DMF> methanol. The preferential solvation free energies of Na~+ for the pairs solvenst, methanol-DMF and water-acetone, were evaluated as -2.7 kJmol~(-1) for DMF to methanol and 4.6 kJmol~(-1) for acetone to water.
~(23)Na~+ chmical shift in methanol-benzene is independent of the content of benzene. It verified 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 linewidth 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.