Synthesis and Crystal Structure of Li+@Fluoreno[60]fullerene: Effect of Encapsulated Lithium Ion on Electrochemistry of Spiroannelated Fullerene

摘要

The reaction of [Li+@C-60]TESI- (TFSI = bis(trifluoromethanesulfonyl)imide) with 9-diazofluorene directly produced a [6,6]-adduct of lithium-ion-containing fluoreno[60]fullerene, [6,6]-[Li+@C-60(fluoreno)]TFSF-, which was crystallographically characterized. Cyclic voltammetry of the compound showed a reversible one-electron reduction wave at -0.51 V (vs Fc/Fc(+)) and an irreversible reduction wave for the second electron. The latter was attributed to opening of the three-membered ring due to strong stabilization of the resulting sp(3)-carbanion by the encapsulated Li+ and formation of a 147 pi-electron aromatic fluorenyl anion.