A pair of diphosphine-protected gold nanoclusters differing by a single gold atom on the kernel surface

Abstract

The atom-level manipulation of atomically precise metal nanoclusters (NCs) has attracted considerable attention due to its potential for facilitating the elucidation of structure–property relationships. Herein, we report two atomically precise gold NCs, [Au₉(DPPF)₄]Cl₃ (DPPF = bis(diphenylphosphino)ferrocene) (Au₉) and [Au₈(DPPF)₄]Cl₂ (Au₈), identified by single-crystal X-ray diffraction (SCXRD) and electrospray ionization mass spectrometry (ESI-MS). SCXRD analysis revealed that the two gold NCs contain a similar Au₈ unit enclosed by a tetrahedral framework consisting of four DPPF ligands, and the only difference is the addition of a gold atom on the kernel surface of the Au₉ NC, which can be resected to form the Au₈ NC. This represents the achievement of precise atomic “tailoring” of the surface of a kernel of a gold NC without altering the other parts of the structure. Notably, the two NCs allow for the identification of free valence electrons (6e). A further investigation into their electronic structures and electrocatalytic CO₂ reduction reaction activity was performed to explore the functionality of such minimal kernel tailoring at the atomic level. This study not only enriches the family of diphosphine-protected small-sized gold NCs but also realizes the atomic-level tailoring of specific sites on a nanoparticle.