【Abstract】 The quantum chemical investigations of some representative bis-adducts of C₆0, C₆0O₂, C₆0（NH）₂, C₆0（CH₂NHCH₂）₂ and C₆0（SO₄）₂ have been carried out at the AM1 and PM3 semi-empirical molecular orbital levels. The relative energies of various isomers of these C₆0 bis-adducts have been calculated. For C₆0O₂ and C₆0（NH）₂ with the sterically non-demanding addends, cis-1 isomer resulted from 1,2-additions to adjacent 6/6 ring fusion is the lowest energy structure; for C₆0（CH₂NHCH₂）₂ and C₆0（SO₄）₂ with sterically demanding addends, the most energetically preferred structure is e isomer. This is consistent with and enhances the general rule for regio-selectivity of fullerene C₆0 established by Hirsch, though Hirschs rule is summarized on the basis of methanofullerenes. The thermodynamic analysis is not significant to explain the experimentally observed regiochemistry for C₆0 bis-adducts, and the kinetic reasons or mechanisms may dominant in determining the regioselectivity of fullerene bis-adducts. Further addition patterns for multiple addition were also discussed.更多还原