Reactions of transition metal clusters with small molecules

Atoms and small molecules react with transition metal clusters in ways that are analogous to the physisorption and chemisorption reactions observed on the corresponding extended metal surface. However, often underlying these similarities are size-dependent variations in the reaction mechanisms and r ates, the interpretation of which requires a detailed understanding of the structures of both the bare metal cluster substrates and the cluster-molecu le complexes. Although polyatomic transition metal clusters cannot be chara cterized by the traditional methods of molecular spectroscopy, the combinat ion of other physical and chemical probes can provide qualitative and semiq uantitative structural information. These techniques, when combined with eq uilibrium geometries calculated using ab initio or semiempirical methods, p rovide a detailed picture of the structural origin of metal cluster reactiv ity and its variation with size.