Transition-metal C60 bonding by guided ion beam scattering

Ion beam scattering techniques are used to examine interactions of transition-metal ions with C-60 over the collision energy range from 1-100 eV. The metals studied are iron, manganese, chromium, molybdenum, and tungsten. For each metal ion, in addition to charge transfer and dissociative charge transfer, two distinct types of MC60+ complexes are observed. One forms with no activation barrier at low collision energies, is weakly bound (1-3 eV), and always decomposes by loss of metal. We attribute this to an exohedral coordination complex, as has been proposed by others who have seen this type of complex. A second type of MC60+ complex is observed at collision energies above similar to 10 eV. This high energy complex has a substantial activation barrier to formation, is chemically bound, and decomposes by loss of metal dicarbide (MC2) or metal. We propose that this complex is a network bound structure, with the metal atom probably sitting above the fullerene surface, chemically bound to two or more carbon atoms. (Int J Mass Spectrom 185/186/187 (1999) 603-615) (C) 1999 Elsevier Science B.V.