Simple bond patterns predict the stability of Diels–Alder adducts of empty fullerenes

摘要: We present an extensive and systematic study on the regioselectivity of Diels-Alder (DA) cycloadditions to empty fullerenes, covering whole range cage sizes from C60 C180. Reaction energies obtained DFT calculations, which correlate with activation barriers, can be well reproduced by using a simple Huckel model, indicating that π electronic effect is key factor determining relative stability DA adducts. Based these results, we propose couple rules thumb, in terms set bond patterns, as visual guide for approximate prediction reactive sites. Moreover, suggest two quantitative descriptors regioadducts fullerenes; one combines free valences orders involved addition, other characterizes local aromaticity around addition site. The latter criterion allows us easily rationalize proposed rules.