Probing the structures and bonding of auropolyynes, Au-(C≡C) n -Au- (n = 1-3), using high-resolution photoelectron imaging

Free-Energy Landscape and Isomerization Rates of Au4 Clusters at Finite Temperatures

In metallic nanoparticles, the geometry of atomic positions controls the particle's electronic band structure, polarizability, and catalytic properties. Analyzing the structural properties is a complex problem; the structure of an assembled cluster changes from moment to moment due to thermal fluctuations. Conventional structural analyses based on spectroscopy or diffraction cannot determine the instantaneous structure exactly and can merely provide an averaged structure. Molecular simulations offer an opportunity to examine the assembly and evolution of metallic clusters, as the preferred assemblies and conformations can easily be visualized and explored. Here, we utilize the adaptive biasing force algorithm applied to first-principles molecular dynamics to demonstrate the exploration of a relatively simple system, which permits a comprehensive study of the small metal cluster Au₄ in both neutral and charged configurations. Our simulation work offers a quantitative understanding of these clusters' dynamic structure, which is significant for single-site catalytic reactions on metal clusters and provides a starting point for a detailed quantitative understanding of more complex pure metal and alloy clusters' dynamic properties.

Observation of unsaturated platinum carbenes Pt2C2n - (n = 1-3) clusters: A photoelectron imaging spectroscopic and theoretical study

The structural and bonding properties of the Pt₂C_2n ^- (n = 1-3) complexes have been investigated by mass-selected photoelectron velocity-map imaging spectroscopy with quantum chemical calculations. The adiabatic detachment energies and vertical detachment energies of Pt₂C_2n ^- have been obtained from the measured photoelectron imaging spectra. Theoretical results indicate that the lowest-energy isomers of Pt₂C_2n ^- (n = 1-3) possess linear chain-shaped configurations. The binding motif in the most stable isomer of Pt₂C₂ ^- has a linear cumulenic structure with a Pt=C=C=Pt configuration, and the structural characteristic persists up to all the lowest-energy isomers of the Pt₂C₄ ^- and Pt₂C₆ ^- anions. The chemical bonding analyses indicate that the Pt₂C_2n ^- (n = 1-3) complexes have multicenter two-electron characteristics.

Does gold behaves as hydrogen? A joint theoretical and experimental study

It has been established that the noble-metal-H analogue has been found in a large number of noble-metal-ligand clusters in view of geometric and electronic structures. Here, we demonstrated a different view of noble-metal-H analogue between noble-metal and hydrogen in M(SCH3)2 - (M = Cu, Ag, Au and H) systems. Although H(SCH3)2 - is a typical ion-hydrogen bonding cluster dramatically different from the chemical bonding clusters of M(SCH3)2 - (M = Cu, Ag and Au), the comparison of the two typical bonding patterns has not yet been fully investigated. Through a series of chemical bonding analyses, it is indicated that the evolution has been exhibited from typical ionic bonding in Cu(SCH3)2 - to a significant covalent bonding nature in Au(SCH3)2 - and hydrogen bonding dominating in H(SCH3)2 -. The comparison of M(SCH3)2 - (M = Cu, Ag and Au) with H(SCH3)2 - illustrates the differences in bonding between noble metals and hydrogen, which are mainly related to their diverse atomic orbitals participating in chemical bonding.