title: Regioselectivity of Sc2C2@C3v(8)-C82: Role of the Sumanene-Type Hexagon in Diels-Alder Reaction.
abstract: Recently, several experiments have demonstrated high chemical reactivity of the sumanene-type hexagon in Sc2C2@C82. To further uncover its reactivity, the Diels-Alder reaction to all the nonequivalent C-C bonds of C82 and Sc2C2@C82 has been investigated by density functional theory calculations. For the free fullerene, the [5,6] bond 7 is the thermodynamically most favored, whereas the addition on the [6,6] bond 3 has the lowest activation energy. Diels-Alder reaction has no preference for addition sites in the sumanene-type hexagon. However, in the case of the endohedral fullerene, the [6,6] bond 19 in the special hexagon becomes the most reactive site according to both kinetic and thermodynamic considerations. Further analyses reveal that bond 19 in Sc2C2@C82 exhibits the shortest bond length and third largest π-orbital axis vector. In addition, the LUMOs of bond 19 are also symmetry-allowed to interact with butadiene.
authors.affiliation: Institute for Chemical Physics & Department of Chemistry, State Key Laboratory of Electrical Insulation and Power Equipment, School of Science, Xi'an Jiaotong University , Xi'an 710049, China.
authors.forename: Pei
authors.initials: P
authors.lastname: Zhao
authors.affiliation: Institute for Chemical Physics & Department of Chemistry, State Key Laboratory of Electrical Insulation and Power Equipment, School of Science, Xi'an Jiaotong University , Xi'an 710049, China.
authors.forename: Xiang
authors.initials: X
authors.lastname: Zhao
authors.affiliation: Institute for Molecular Science , Okazaki 444-8585, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ehara