Stable radical anions inside fullerene cages: formation of reversible electron transfer systems

The complexation behavior of La(2)@C(80) dimetallofullerenes with organic donor molecules (D) in solution has been investigated. It has been shown that La(2)@C(80) and D form 1:1 complexes as a result of electron transfer interactions in the ground state. The equilibrium between La(2)@C(80)/D and [La(2)@C(80)](•-)/[D](+) in solution is readily controlled by changing the temperature and solvent.