Facile Access to Azafullerenyl Cation C59N+ and Specific Interaction with Entrapped Molecules

The facile preparation of azafullerenyl cation C59N+ has been achieved by the assistance of trifluoromethanesulfonic acid. The thus formed C59N+ was quite stable in solution over 1 month and can be used as an intermediate for the electrophilic reaction. Applying this method to endohedral azafullerenes, corresponding cations (H2@C59N+ and H2O@C59N+) were prepared and the dynamic behavior of entrapped molecules was studied on the basis of 1H NMR relaxation time measurements. The results indicated that there is strong intramolecular C59N+···Oδ−H2 interaction in H2O@C59N+, which stands in contrast to isoelectronic H2O@C60 with no electrostatic interaction. We also demonstrated that the magnetic shielding environment inside the C59N+ cage closely resembles that for isoelectronic C60.