Multinuclear PGSE diffusion and overhauser NMR studies on a variety of salts in THF solution

H-1, F-19, and Li-7 pulsed gradient spin-echo (PGSE) NIVIR measurements for a series of salts are reported. The Li-7 is shown to complement the H-1 and F-19 measurements; however, the use of higher concentrations (for the less-sensitive Li-7) can lead to aggregation. For all of the salts discussed {Li(BF4); (n-Bu4N)(BF4), a trinuclear Ru cluster; [Ir(1,5-COD)(4)](BF4), where 4 is a chiral P,N ligand; and the crown ether stabilized potassium salt, [K(18-crown-6)(NPh2)], 6}, the use of THF seems to promote strong ion pairing. In several cases, the degree of ion pairing approaches 100%. In THF solution, the potassium salt, 6, prefers to exist as a more classical ion pair rather than as the pi complex found in the solid state. In some cases, H-1, H-1 NOESY and H-1, F-19 HOESY spectra help to pinpoint the cation/anion spatial relationship.