Trifluoromethyl Derivatives of Elusive Fullerene C98.

Data concerning the isomeric composition of C98 and the chemistry of C98 derivatives are scarce due to very low abundance of C98 in the fullerene soot. Trifluoromethylation of C98 -containing mixtures followed by HPLC separation of CF3 derivatives and single crystal X-ray diffraction study resulted in structural characterization of four compounds C98 (248)(CF3 )18/20 , C98 (116)(CF3 )18 , and C98 (120)(CF3 )20 . To date, these compounds represent the largest fullerenes isolated as CF3 derivatives with experimentally determined molecular structures. The addition patterns of C98 (CF3 )18/20 are discussed in detail revealing the stabilizing factors, such as isolated double C=C bonds and benzenoid rings on C98 fullerene cages. A detailed comparison with the addition patterns of the known C98 Cln allowed us to contribute to the better understanding the chemistry of elusive C98 fullerene.