Analysis of electronic delocalization in buckminsterfullerene (C60)

Buckminsterfullerene (C-60) presents an extensive conjugation that, in principle, should lead to a high delocalization of its electrons, together with a notorious aromaticity. However, previous studies have shown that C-60 behaves chemically and physically as an electron-deficient alkene rather than an electron-rich aromatic system. In the current work, we try to better elucidate the extension of electron delocalization in C-60 by computing the delocalization index for a given carbon atom of C-60. We show that, in C-60, local electron delocalization per carbon atom is lower than that in benzene and naphthalene. However, C-60 presents a global electron delocalization per carbon atom that is almost the same as that of clearly aromatic systems such as benzene or naphthalene. This is attributed to the fact that the electron charge of each atom in C-60 can be shared with a larger number of atoms. (C) 2004 Wiley Periodicals, Inc.