A molecular beam of multilayer vanadium-benzene organometallic complexes Vn(C6H6)m was produced by a laser vaporization synthesis method. The magnetic moments of the complexes were measured by a molecular beam magnetic deflection technique, and were found to increase with the number of vanadium atoms in the cluster, showing that the unpaired electrons, which occupy the nonbonding dsigma orbitals localized on the metal atoms, couple ferromagnetically. These sandwich species represent a new class of one-dimensional molecular magnets in which the transition metal atoms are formally zerovalent.

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 rates, the interpretation of which requires a detailed understanding of the structures of both the bare metal cluster substrates and the cluster-molecule complexes. Although polyatomic transition metal clusters cannot be characterized by the traditional methods of molecular spectroscopy, the combination of other physical and chemical probes can provide qualitative and semiquantitative structural information. These techniques, when combined with equilibrium geometries calculated using ab initio or semiempirical methods, provide a detailed picture of the structural origin of metal cluster reactivity and its variation with size.