Bader’s bond ellipticity as a reactivity index for stepwise [2 + 1]-cycloaddition to the C ₆₀ fullerene

Selectivity of chemical reactions of fullerenes is a challenge of fullerene science, as there is no universal tool to predict the favorability of the alternative reaction modes within one reactivity index. This challenge is addressed to both experimental and theoretical chemistry. In the present work, using Bader’s theory Atoms-in-Molecules, we have computationally studied the ellipticities of the C=C bonds in the molecules of fullerene adducts C60Xn (n = 1–3) with symmetric addends X = CH2 and O. We have obtained the correlations between the thermodynamic stability of the fullerene adducts and bond ellipticities in the molecules of their precursors. The found regularity may be further used for predicting the reactivity of other fullerene derivatives and estimating the regioselectivity of their cycloaddition reactions.