Odd-even effect of the number of free valence electrons on the electronic structure properties of gold-thiolate clusters

ABSTRACT

It is essential to understand the intrinsic stability of the gold-thiolate clusters, which present extensive potential applications in many fields such as the catalysis, biomedicines and molecular machines. The electronic structures and aromaticity indexes of a series of Au_m(SH)_n (m, n = 5–12) were comprehensively investigated through energetic, vibrational, magnetic, and electronic density properties, which are highly sensitive to the size and topological structure of the cluster. Generally, computational results of energy gap between the frontier molecular orbitals, normalized atomization energy (NAE), and electron localization function (ELF)-σ values exhibit the odd-even effect, in which clusters with the even number of free valence electrons, being reflected by the value of (m–n), possess relatively higher stability than the odd one. However, it is difficult to describe the stability of cluster with the sophisticated three-dimensional structure through one single aromaticity index such as the nucleus-independent chemical shift (NICS) value. Principal component analysis and clustering analysis of the calculation results of Au_m(SR)_n clusters suggest that the value of (m–n) and the Au₄ unit are important for predicting the stability of the Au clusters.

GRAPHICAL ABSTRACT

KEYWORDS:

• Gold-thiolate clusters
• bond strength order
• principal component analysis
• clustering analysis

Acknowledgements

We are grateful to the High Performance Computing Centre of Nanjing University for providing the IBM Blade cluster system.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the National Key Research and Development Program of China under [grant number 2017YFB0702600, 2017YFB0702601] and the National Natural Science Foundation of China under [grant number No. 21673111].