Enantiospecific cis–trans Isomerization in Chiral Fulleropyrrolidines: Hydrogen-Bonding Assistance in the Carbanion Stabilization in H2O@C60

The stereochemical outcome of cis–trans isomerization of optically pure [60], [70], and endohedral H2O@C60 fulleropyrrolidines reveals that the electronic nature of substituents, fullerene size, and surprisingly the incarcerated water molecule plays a crucial role in this rearrangement process. Theoretical DFT calculations are in very good agreement with the experimental findings. On the basis of the experimental results and computational calculations, a plausible reaction mechanism involving the hydrogen-bonding assistance of the inner water molecule in the carbanion stabilization of endofullerene is proposed.