Genesis of [5,6]-Open Regioisomer via Direct Benzyne-C60 Cycloaddition

Cycloaddition is one of the best studied types of reactions in organic chemistry of fullerenes, engendering in [6,6]-closed adducts in the vast majority of cases. Notwithstanding that a formation of open fulleroid structures is undoubtedly of theoretical interest, no one has demonstrated the conformation of [5,6]-open fulleroid via the direct cycloadditions. Here, we establish that cycloaddition between C60 and benzyne in situ generated from 2-amino-4,5-dibutoxybenzoic acid affords a new type of elusive [5,6]-open structure that is characterized on the basis of NMR, UV-Vis spectroscopies, and cyclic voltammograms. Additionally, from the density functional theory (DFT) calculations for possible [5,6]-open and [6,6]-closed adducts induced by the benzyne-C60 reaction, one should be note that the quantum-chemical features such as the charge distributions, binding characteristics, and frontier molecular orbital levels, are affected by the different binding modes in C60 cage