Effect of Incarcerated HF on the Chemical Reactivity of Endohedral HF@C60

Abstract

The first chemical modification on the endohedral HF@C60 is reported. In particular, the isomerization from optically pure (2S,5S)-cis-pyrrolidinofullerene 2b to (2S,5R)-trans-pyrrolidinofullerene 2b has been studied and compared with empty C60 (2a) and endo-hedral H2O@C60 (3). Interestingly, the incarcerated HF molecule contributes to increase the isomerization rate through a H-bonding assistance involving weak hydrogen bonding without affecting the final cis-trans ratio or promoting the loss of enantioselective control through the retro-cycloaddition reaction. The comparative study shows a kinetic order for the isomerization process of H2O@C60 ˃ HF@C60 ˃ C60, thus confirming the effect of the incarcerated species on the zwitterionic intermediate stability