Regioselectivity in multiple cycloadditions to fullerene C60: vibronic coupling density analysis

We theoretically investigate multiple cycloadditions of butadienes to fullerene C-60 with the concept of vibronic coupling density (VCD) as a reactivity index. Recently, we have clarified that C-60 bears ethylene moieties at its reactive sites as functional groups, on the basis of VCD. In this study, we calculate the VCDs of C-60 adducts with n butadienes (n=1,..., 5) and show that the ethylene moieties are conserved with almost the same distributions as those in C-60. The VCD analysis predicts that the hexakisadduct with a six-fold axis is finally obtained, which is consistent with experimental observations. (C) 2014 Elsevier Ltd. All rights reserved.