Computer modeling of C2 cluster addition to fullerene C60

The reaction between C2 cluster and C60 fullerene resulting in C2 insertion to C60 with formation of closed C62 cage (reaction of C2 ingestion by C60) was investigated by the semiempirical MNDO‐PM3 method. The geometries and energies of extremal points on the C62 potential energy surface were calculated. Several reaction pathways leading to the formation of three different closed C62 fullerenes were investigated. All insertion reactions proceed stepwise through intermediate adducts of different structures. The main reaction pathways were found to be addition of C2 by its one side to the 6,6‐ or 5,6‐bond of C60 with formation of primary unclosed C62 adducts of “ball‐with‐fork” structures, lying in deep potential wells. Back reaction of C2 detachment from primary adducts can compete with that of their transformation to the closed C62 cages inasmuch as calculated activation barriers of the both reactions are comparable. Model calculations at the B3LYP/6‐31G* level, using C32H12 semisphere instead of C60, confirmed the conclusion about two competitive pathways of the primary adducts transformation, C2 detachment, and C2 ingestion. The concerted insertion of C2 to C60 was realized only in the case of severe restrictions on starting geometry of the C2 + C60 system. The results of calculations explain recent experimental data on the formation of metastable adducts upon addition of C2 to C60, obtained using the time‐of‐flight mass spectrometer with laser desorption. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002