Addition of CF2group to endohedral fullerene Sc3N@Ih-C80

We report the first successful synthesis of a CF(2)derivative of the stable endohedral fullerene Sc3N@I-h-C-80. Reaction with CF2ClCOONa yields a singleC(s)-symmetric Sc3N@C-80(CF2) adduct where the CF(2)group is inserted into a [6,6]-bond and opens it to 2.3 angstrom between the bridgehead carbon atoms. As evidenced by absorption and fluorescence spectroscopy as well as cyclic voltammetry, both the HOMO and the LUMO level of Sc3N@C-80(CF2) are slightly (ca.0.1 eV) downshifted with respect to the parent Sc3N@I-h-C-80, so the HOMO-LUMO gap remains essentially unchanged. The DFT calculations suggest that the reaction mechanism is not the previously assumed [2 + 1]-cycloaddition of :CF(2)carbene but rather nucleophilic addition of CF(2)Cl(-)anion followed by elimination of Cl(-)and closing of the CF(2)bridgeviaintramolecular nucleophilic substitution. Selective formation of the [6,6]-Sc3N@C-80(CF2) turns out to be kinetically controlled and promoted by a particular orientation of the endohedral Sc3N cluster with respect to the CF(2)Cl(-)addition site. In its turn, the CF(2)addend partly hampers the rotation of Sc3N the endohedral cluster compared to its quasi-free reorientations in the parent Sc3N@I-h-C-80.