Metal−Metal Coordination Chemistry:  Free Clusters of Group 11 Elements with Sodium

Abstract

Mixed metal clusters of sodium with copper, silver, and gold were produced by supersonic expansions at well-defined thermodynamic conditions. Differences in the behavior toward binary alloying, cluster formation, and relative thermodynamic stabilities are discussed within a structureless, delocalized, electronic shell model and using molecular orbital arguments and the different strengths of the relativistic effects of the coinage metals. Free-energy changes (∆G) of selected exchange reactions are determined, showing the substitution of gold atoms to be thermodynamically the most favored. This is due to the preferred s-d hybridization in gold atoms, leading to a stronger metal-metal interaction. The measured ionization potentials reveal a distinct shell closing at the octamer for all three heterosystems. The drop of the ionization potential going from the octamer to the nonamer is most pronounced for the sodium-silver heteroclusters and is almost as large as for pure sodium clusters.

Nanoalloys: From Theory to Applications of Alloy Clusters and Nanoparticles

“…Small clusters of Cu, Ag, and Au with Na as well as Cs x Au and Na x Au clusters have also been studied experimentally and theoretically. , …”

A Photoelectron Spectroscopic and Computational Study of Sodium Auride Clusters, NanAun- (n = 1−3)

“…Some bimetallic gold−sodium clusters have been studied in the gas-phase previously. − Neutral sodium−gold Na m Au n clusters ( m = 0−10, n = 6−13) were produced by Hoshino et al., who measured the ionization potentials of Na m Au n . Heiz et al investigated gold-doped alkali−metal clusters Na n Au and Cs n Au; they measured the ionization potentials of these clusters and performed theoretical calculations at the relativistic density-functional level.…”

Catalytic Oxidation of Carbon Monoxide on Monodispersed Platinum Clusters: Each Atom Counts

“…Included are the calculated positions of the centers of the d-bands for Pt10 (-7.2 eV) 44 and Pt13 (-6.3 eV). 45 Dotted line: classical conductive droplet model 50 (the expected fine structure of the ionization potentials observed for small metal clusters 50,51 is not taken into account). Dissociation is favored if the energy of the cluster's HOMO is close to the antibonding πg* state of oxygen.…”