The Pivotal Radical Intermediate [Au21(SR)15]+ in the Ligand-Exchange-Induced Size-Reduction of [Au23(SR)16]- to Au16(SR)12

Mengting Cui; Yanan Shi; Xiangyu Ma; Qingliang Li; Ling Chen; Lichao Zhang; Junfei Wu; Haizhu Yu; Manzhou Zhu

doi:10.1021/acsnano.3c12765

The Pivotal Radical Intermediate [Au₂₁(SR)₁₅]⁺ in the Ligand-Exchange-Induced Size-Reduction of [Au₂₃(SR)₁₆]^- to Au₁₆(SR)₁₂

ACS Nano. 2024 Feb 27;18(8):6591-6599. doi: 10.1021/acsnano.3c12765. Epub 2024 Feb 2.

Authors

Mengting Cui¹, Yanan Shi¹, Xiangyu Ma¹, Qingliang Li¹, Ling Chen¹, Lichao Zhang¹, Junfei Wu¹, Haizhu Yu¹, Manzhou Zhu¹

Affiliation

¹ Department of Chemistry and Centre for Atomic Engineering of Advanced Materials, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology and Anhui Province Key Laboratory of Chemistry for Inorganic/Organic Hybrid Functionalized Materials, Anhui University, Hefei, Anhui 230601, China.

PMID: 38305198
DOI: 10.1021/acsnano.3c12765

Abstract

The atomic precision of sub-nanometer-sized metal nanoclusters makes it possible to elucidate the kinetics of metal nanomaterials from the molecular level. Herein, the size reduction of an atomically precise [Au₂₃(CHT)₁₆]^- (HCHT = cyclohexanethiol) cluster upon ligand exchange with HSAdm (1-adamantanethiol) has been reported. During the 16 h conversion of [Au₂₃(CHT)₁₆]^- to Au₁₆(SR)₁₂, the neutral 6e Au₂₁(SR)₁₅, and its 1e-reduction state, i.e. the 5e, cationic radical, [Au₂₁(SR)₁₅]⁺, are active intermediates to account for the formation of thermodynamically stable Au₁₆ products. The combination of spectroscopic monitoring (with UV-vis and ESI-MS) and DFT calculations indicates the preferential size-reduction on the corner Au atoms on the core surface and the terminal Au atoms on longer Au_nS_n+1 staples. This study provides a reassessment on the electronic state of the Au₂₁ structure and highlights the single electron transfer processes in cluster systems and thus the importance of the EPR analysis on the mechanistic issues.

Keywords: Atomic precision; Gold nanoclusters; Mechanism; Radical intermediate; Size-reduction.