Identification of cyano dianions of C60 by electrospray mass spectrometry

We have observed three dianions of cyano-adducted buckminsterfullerene, namely C60(CN)22−, C60(CN)42− and C60(CN)62−, in the negative-ion electrospray mass spectrometry (EMS) of freshly prepared solutions of C60 and NaCN. The results of semi-empirical calculations show that the dianions are likely to have radically different geometries to those preferred by the corresponding neutral molecules. So while C60(CN)6 exhibits the same structure as C60Cl6, its dianion C60(CN)62− has a preferred geometry in which CN− and (CN)5− groups are located on opposite sides of the C60 sphere.