1H, 19F-HOESY and PGSE diffusion studies on ionic liquids: The effect of co-solvent on structure

1H, 19F-HOESY studies on the ionic liq. based on 1-butyl-3-methylimidazolium tetrafluoroborate, [C4C1i.m.]BF4, [C4C1i.m.][N(OTf)2], and, partially, [C4C1i.m.]PF6, are reported. The addn. of methanol separates the ions; however, in dichloromethane soln. the anions and cations show strong HOESY contacts even after diln. and taken together with the PGSE diffusion measurements, the data suggest strong ion pairing in this solvent.