Impurity Atoms on Small Transition Metal Clusters. Insights from Density Functional Model Studies

Unusual Bonding in Platinum Carbido Clusters

Vibrational spectroscopy and density functional theory calculations are used to determine the structures of small gas-phase platinum carbido clusters PtnC(+), n = 3-5. The carbon atom is found to prefer three-coordinate binding sites near the center of the cluster, in contrast to most previously investigated adatoms on transition metal clusters. The Pt3C unit is particularly stable, and binding of the carbon atom also leads to significant rearrangement of the metal framework when compared to the bare clusters.

Hydrogen activation and metal hydride formation trigger cluster formation from supported iridium complexes

The formation of iridium clusters from supported mononuclear iridium complexes in H(2) at 300 K and 1 bar was investigated by spectroscopy and atomic-resolution scanning transmission electron microscopy. The first steps of cluster formation from zeolite-supported Ir(C(2)H(4))(2) complexes are triggered by the activation of H(2) and the formation of iridium hydride, accompanied by the breaking of iridium-support bonds. This reactivity can be controlled by the choice of ligands on the iridium, which include the support.