Isolation of gravimetrically quantifiable alkali metal arenides using 18-crown-6

Small, polyaromatic radical monoanions, e.g. C10H8-center dot, are a valued class of reagents that are routinely used as potent outer-sphere reductants. Owing to their high reactivity, these arenides are typically prepared in solution and used in situ. We have found that treatment of M[arene(-center dot)] (M = Li, Na, K; arene = biphenyl, naphthalene, anthracene, perylene) with the 18-crown-6 polyether readily provides [M(18-c-6)(solvent)(n)][arene(-center dot)] as thermally stable, easily handled, bottleable crystalline solids that can be stored indefinitely under inert conditions.