Adsorption of C60 on nickel clusters at high temperature

The adsorption of C-60 on nickel clusters has been studied in a flow-tube reactor at temperatures between 823 and 1073 K. Saturation coverages of C-60 have been determined for Ni-2-Ni-72 and show a size dependence consistent with C-60 adsorption on essentially spherical Ni-n clusters. There is no evidence for C-60 decomposition. The configuration of the adsorbed C-60 molecules appears to change from tetrahedral-->octahedral-->cubic-->less symmetrical arrangements as metal cluster size increases. An RRK modeling of the first C-60 that binds to the nickel clusters yields a binding energy in excess of 2.06 eV. The binding energy appears to decrease with decreasing metal nuclearity of the binding site, with binding to atop sites on the Ni-n clusters being relatively weak. It is argued that electron transfer to the C-60 ligands is limited by charging of the central Ni-n core and that this may provide a way of controlling the extent of electron transfer to the adsorbed molecules. [S0163-1829(99)03720-0].