Identification of dianions of C84 and C90 by electrospray mass spectrometry

We have observed the dianions of the fullerenes C84 and C90 in the negative-ion electrospray mass spectrometry (EMS) of specific solutions of a commercial sample of a mixture of higher fullerenes (C60 to C96) which contains mostly C84. The results of semiempirical calculations show that, in contrast to the cases of C60 and C70, these dianions are likely to have strongly positive electron affinities, explaining their stability in a high-vacuum environment. While C842− has recently been observed in the isolated state, this is the first observation of the intrinsically stable C902−.