Cross-over in the structure of the charged (C60)nn− oligomers Original Research Article

The stability of the cycloadduct (D_D2h) and the single-bonded (S_C2h) structure of the linear c60 oligomers with one extra electron per buckyball (C60)nn− (n = 2,3,4) was investigated using semiempirical AM1 calculations. The single-bonded structure was found to be more stable than the cycloadduct one in the case of the dimers. However, the single-bonded tetramer is already unstable and dissociates into two S_C2h dimers. On the other hand, the stability of the cycloadduct structure increases with increasing chain length.