Computer modeling of C 2 cluster addition to fullerene C 60

The reaction between C 2 cluster and C 60 fullerene resulting in C 2 insertion to C 60 with formation of closed C 62 cage (reaction of C 2 ingestion by C 60 ) was investigated by the semiempirical MNDO‐PM3 method. The geometries and energies of extremal points on the C 62 potential energy surface were calculated. Several reaction pathways leading to the formation of three different closed C 62 fullerenes were investigated. All insertion reactions proceed stepwise through intermediate adducts of different structures. The main reaction pathways were found to be addition of C 2 by its one side to the 6,6‐ or 5,6‐bond of C 60 with formation of primary unclosed C 62 adducts of “ball‐with‐fork” structures, lying in deep potential wells. Back reaction of C 2 detachment from primary adducts can compete with that of their transformation to the closed C 62 cages inasmuch as calculated activation barriers of the both reactions are comparable. Model calculations at the B3LYP/6‐31G* level, using C 32 H 12 semisphere instead of C 60 , confirmed the conclusion about two competitive pathways of the primary adducts transformation, C 2 detachment, and C 2 ingestion. The concerted insertion of C 2 to C 60 was realized only in the case of severe restrictions on starting geometry of the C 2 + C 60 system. The results of calculations explain recent experimental data on the formation of metastable adducts upon addition of C 2 to C 60 , obtained using the time‐of‐flight mass spectrometer with laser desorption. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002