Determining addition pathways and stable isomers for CF₃ functionalization of endohedral Gd@C₆₀

Using density functional theory approaches, we follow the sequential addition of CF₃ functional groups to the surface of the metallic endofullerene species Gd@C₆₀. The presence of gadolinium in the interior of the cage strongly influences the addition sequence. The calculations are able to successfully identify end points in the addition sequence at Gd@C₆₀(CF₃) , n = 3 and two isomers at n = 5, in predictive agreement with experiment. Inverting the algorithm to determine the most labile groups also identifies the correct positively charged $$ isomer, as confirmed by experimental mass spectra. The importance of surface mobility, notably at later stage addition, is discussed.