Infrared spectra and structures of C60Rhn+ complexes

Abstract

Metal clusters supported on carbonaceous substrates are of interest in catalysis, hydrogen storage, and other fields. In this paper, the structures and the infrared spectra of C60Rhn+ (n = 1–6) fullerene-metal complexes are studied by a combination of mass-selective infrared spectroscopy and theoretical calculations. It is found that clustering of Rh on the surface of the fullerene is preferred over surface wetting. For Rh4+ and Rh6+, the structures of the adsorbed clusters are different from those of the free clusters. There is electron transfer from the metal cluster to the fullerene in neutral C60Rhn, and in cationic C60Rhn+ the electron deficit is shared by the metal cluster and the fullerene. Adsorption of Rhn clusters leads to degeneracy lifting of the most intense C60 features in the infrared spectra that were measured in the 300–850 cm−1 range. Agreement is obtained, in general, between the experimental infrared spectra of D2-tagged C60Rhn+ and the calculated spectra for untagged C60Rhn+, except in the 600–750 cm−1 region, where features mainly arise from the presence of D2-messenger molecules adsorbed on the Rhn clusters.