Acidity and delocalisation of C70-substituted hydrofullerenes: an ab initio quantum-chemical study

An ab initio HF/3-21G study is made of the acidity of a series of substituted [70]hydrofullerenes. All systems under consideration result from substituting one hydrogen atom in C70H2 by a functional group, for which a series of alkyl and fluorine- and chlorine-containing groups has been chosen. Acidities are obtained via a previously set up correlation with calculated gas-phase deprotonation energies. Electronic delocalisation in the conjugate base is seen to play an important role in the fairly high acidity of these systems. Also, the interplay of group hardness and electronegativity on the acidity sequence is shown.