Expanding on bond dissociation energy of gold

In order to understand how transition metal clusters behave in the gaseous phase, scientists first need to explore the thermochemistry of transition metal dimers. A better understanding of these heterogeneous catalytic processes could one day improve industrial applications. While previous studies have focused on lighter transition metals, relatively fewer studies have characterized the movement of electrons in the outer electron shells (4d and 5d) of heavier transition metal dimers.

The new paper reports the first direct measurement of the bond dissociation energy for the gold dimer cation. Using guided ion beam tandem mass spectrometry, the team obtained a value of 2.20 ± 0.21 eV for the bond dissociation energy of this simple species.

Peter Armentrout, an author of the paper, said he was excited when his group was able to measure a simple, fundamental property for the first time. “By benchmarking the theory for a simple species like gold dimer cations, we can expand to larger species theoretically with more confidence in the results,” he said.

Subsequent analysis suggests that the relatively weak bond can be explained by a single electron bonding in the 6s-orbitals as the experimental ground state for gold dimer cations.

“The fact that no one has been able to provide this kind of benchmark information before is intriguing and an accomplishment in and of itself,” Armentrout said. “Our work also validates the experimental approach and provides guidance for future theoretical studies.”

The team plans to next explore how methane, ethene, and carbon monoxide bind to gold dimer cation and their role in catalysis.

Source: “Bond dissociation energy of Au₂⁺: A guided ion beam and theoretical investigation,” by Cameron J. Owen, Nicholas R. Keyes, Changjian Xie, Hua Guo, and P. B. Armentrout, The Journal of Chemical Physics (2019). The article can be accessed at https://doi.org/10.1063/1.5092957 .