Salt and Nonelectrolyte Interactions in Water.

摘要

The sodium-23NMR chemical shift of Na tetraphenylboron was measured in a variety of solvents and ligands. The shifts and line widths were correlated with a number of electron-donor properties of the same materials to see whether Na-23NMR was a useful probe of ion-ligand interactions. Correlations were poor for Na-23shifts in pure ligand solvents and not much better for dilute acetone solutions of the ligand containing Na tetraphenylboron. Normalized values in acetone solution gave better correlations. Of all electron donor properties,the ability of a solvent to accept hydrogen-bonds correlates best with its interaction with Na(+) as measured by the Na-23shift. Water as a bulk solvent is a much better sodium ion solvator than water in dilute acetone solution,but there is no evidence for long-lived hydrates in solution. Cellulose acetate in acetone causes a shift of the Na-23resonance and considerable line-broadening suggesting the presence of relatively long-lived complexes similar to the behavior of crown ethers or glyme solvents. Titration calorimetry was used to determine K,delta G,delta H and delta S for the formation of ion-pairs and also ion-ligand complexes. The ion pair data show behavior closely parallel to conductance data but with consistent differences suggesting that calorimetry measures a wider range of ion-ion interactions than conductance. Measurements for ion-ligand interactions with pure solvents,crown ethers and glymes generally support previous data with a cruder solution calorimeter.