Structures of gas-phase (C60)n(CN)m trianions from reactions of C60 with NaCN in solution

Negative ion electrospray mass spectra of solutions containing C-60 and a 100-fold molar excess of NaCN display numerous polyanionic species of the general form (C-60)(n)(CN)(m)(x-) where n = 1-3, m = 1-7, and x = 1-3. Collision-induced dissociation studies of selected di- and trianions reveal the structures of those ions; e.g., (C-60)(3)(CN)(7)(3-) is shown to be [C-60(CN)(2)... C-60(CN)(3)... C-60(CN)(2)](3-). Simple electrostatic calculations indicate that the effective binding force ("..." in the aforementioned example) between the components may result from a Coulomb barrier acting to prevent spontaneous dissociation of the components.