# Experimental Investigation of the Stability of AunCln+m− (n = 1–5; m = 1, 3, 5, 7) Clusters by Laser Desorption/Ionization Mass Spectrometry

## TL;DR

This study experimentally examines the stability of various gold chloride clusters under different laser intensities.

## Contribution

The paper reports the first experimental investigation of the stability of AunCln+m− clusters using laser desorption/ionization mass spectrometry.

## Key findings

- The relative intensity of AunCln+1− and AunCln+3− clusters decreases with more AuCl units at higher laser intensities.
- Au3Cl8− is the most stable among AunCln+5− clusters.
- Cluster stability is influenced by bond types and laser intensity.

## Abstract

The stability of gold chloride clusters is an important topic in catalysis and nanomaterials, but experimental data are missing. Here, fourteen different clusters were obtained simultaneously using laser desorption/ionization mass spectrometry and were identified as AunCln+m− (n = 1–5; m = 1, 3, 5, 7) or AuCln+1−, Au2Cl2n+1−, Au3Cl2n+2−, Au4Cl2n+1− and Au5Cl2n+2−. Consequently, the effects of laser intensity on their stability were evaluated, considering differences in the AuCl unit or the number of Cl atoms. For the AunCln+1− and AunCln+3− groups, the relative intensity of the clusters decreased with each additional AuCl unit as the laser intensity increased. AunCln+5− clusters showed a different trend in relative intensities: Au3Cl8− > Au2Cl7− > Au4Cl9− > Au5Cl10−. The mononuclear AuCl4− showed the highest stability, which is consistent with their “superhalogen” character. In the Au2Cl2n+1− clusters, Au2Cl5− with Au (III)–Au(I) interaction was more stable at lower laser intensities, while Au2Cl3 with Au(I)–Au(I) bonds became more dominant at higher intensities. Among the Au3Cl2n+2−, Au4Cl2n+1− clusters, those with purely “aurophilic” interactions became increasingly stable with increasing laser intensity. These results emphasize the importance of bond type and cluster size for the stability of gold chloride clusters at different laser intensities.