IDENTIFICATION OF DIANIONS OF C-84 AND C-90 BY ELECTROSPRAY MASS-SPECTROMETRY

We have observed the dianions of the fullerenes C-84 and C-90 in the n egative-ion electrospray mass spectrometry (EMS) of specific solutions of a commercial sample of a mixture of higher fullerenes (C-60 to C-9 6) which contains mostly C-84. The results of semiempirical calculatio ns show that, in contrast to the cases of C-60 and C-70, these dianion s are likely to have strongly positive electron affinities, explaining their stability in a high-vacuum environment. While C-84(2-) has rece ntly been observed in the isolated state, this is the first observatio n of the intrinsically stable C-90(2-). (C) 1998 Elsevier Science B.V. All rights reserved.