Regioselective Sequential Additions of Nucleophiles and Electrophiles to Perfluoroalkylfullerenes: Which Cage C Atoms Are the Most Reactive and Why?

The sequential addition of CN(-) or CH3(-) and electrophiles to three perfluoroalkylfullerenes (PFAFs), C(s)-C70(CF3)8, C1-C70(CF3)10, and C(s)-p-C60(CF3)2, was carried out to determine the most reactive individual fullerene C atoms (as opposed to the most reactive C=C bonds, which has previously been studied). Each PFAF reacted with CH3(-) or CN(-) to generate metastable PFAF(CN)(-) or PFAF(CH3)2(2-) species with high regioselectivity (i.e., one or two predominant isomers). They were treated with electrophiles E(+) to generate PFAF(CN)(E) or PFAF(CH3)2(E)2 derivatives, also with high regioselectivity (E(+)=CN(+), CH3(+), or H(+)). All of the predominant products, characterized by mass spectrometry and (19)F NMR spectroscopy, are new compounds. Some could be purified by HPLC to give single isomers. Two of them, C70(CF3)8(CN)2 and C70(CF3)10(CH3)2(CN)2, were characterized by single-crystal X-ray diffraction. DFT calculations were used to propose whether a particular reaction is under kinetic or thermodynamic control.