Alkali metal solutions in liquid 15-crown-5

Potassium, rubidium, caesium, and mixed alkali metals dissolve in the liquid crown ether, 1,4,7,10,13-pentaoxa-cyclopentadecane (15-crown-5), to give intensely coloured solutions; spectroscopic studies (optical, e.s.r., and n.m.r.) revealed alkali metal anions, solvated electrons, and various cation–electron aggregates in these systems.