The C60O2 structures with a trans (the most distant) arrangement of th
e oxygen atoms are treated by means of the AM1 quantum-chemical method
. Full geometry optimization of the D2h and C2h structures is performe
d together with vibrational harmonic analysis (the latter structure is
lower in energy by about 103 kJ/mol). Low-lying triplet states are po
inted out. In the D2h structure the O-bridged C-C bond is elongated to
1.55 angstrom, while in the C2h is broken.