Computations of Low-Energy Non-Icosahedral Structures of C6− 60

Abstract Owing to the three-fold degeneracy of the LUMO in C60, its hexa-anion is not subjected to Jahn-Teller distortions. In contrast to the accepted presumptions, however, computations at the MNDO, AMI, PM3, SAM1, HF/STO-3G, HF/3-21G, and HF/4-31G levels show that the completely relaxed, non-icosahedral cage of C6− 60is lower in energy. The computed energy gain varies between 60 and 150 kJ/mol and thus, it is consistently significant (the most sophisticated approach, HF/4-31G, yields 93 kJ/mol). The longest C-C bond in the relaxed structures is at most computed 0.05 Å longer compared to the 5/6 bond in the icosahedral C6− 60The symmetry of C6− 60is relaxed to D2 A C2v, isomer is discussed, too.