Impact of internal electron transfer on the structure of C74 encapsulating Sc and La metal atom impurities

Frontier orbital theory as well as the Hückel 4n + 2 rule are discussed as guiding principles for the design and the interpretation of metallofullerene architecture where systems of the form Mi@C74 (M = Sc, La; i = 1,2) serve as examples. Transfer of electrons from the metal impurities to the fullerene enclosure populates preferentially the low‐lying unoccupied molecular orbitals of the cage. It further tends to induce aromaticity in the C5 rings neighboring the impurity sites. These observations are used to derive systematically stable structures of the studied mono‐ and dimetallofullerenes. Various geometries and spin states of M2@C74 (M = Sc, La) are considered, and novel ground state candidates are proposed. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007