Department of Chemistry, Shiraz University, Shiraz, I.R. IRAN
Complexes of benzo-15-crown-5 macrocycle with Li+ and Cs+ ions were investigated by 7Li and 133Cs NMr in a number of nonoqueous solutions. The resulting 1:1 complex with Li+ ion was found to be much more stable than that with Cs+ ion. With the exception of pyridine solutions the stabilities of the complexes varied inversely with the Gutmann donor number of the solvents. Some indirect evidence for the formation of very weak 2:1 complexes was observed.