The pivotal alkyne group in the mutual size-conversion of with nanoclusters

Herein, density functional theory (DFT) calculations were performed to elucidate the mechanism of the reversible single atom size conversion between [Au-10(DMPP)(4)(C6H11C C)](3+) and [Au-9(DMPP)(4)](3+) (DMPP is 2,2'-bis-(dimethylphosphino)-1,1'-biphenyl, the simplified, theoretical model of the experimentally used 2,2'-bis-(diphenylphosphino)-1,1'-binaphthyl). The presence of a unique alkyne group is pivotal to the nucleophilic attack of the phosphine ligand on the electron-deficient Au-10 core. After that, a formal ligand exchange and facile 1,2-P (of the diphosphine ligand) transfer occur to generate the Au-9 cluster product. By contrast, the absence of the alkyne group results in a relatively electron-rich Au-9 core, and thus an electrophilic attack of the Au(alkyne) complex on the most electron-rich metal sites occurs first. After that, the Au(alkyne) migration on the cluster surface, 1,2-P transfer and core-reconstruction occur successively to generate the thermodynamically highly stable Au-10 cluster product.

Automated summary

Density functional theory calculations were used to elucidate the mechanism of reversible single atom size conversion between [Au-10(DMPP)(4)(C6H11C C)](3+) and [Au-9(DMPP)(4)](3+). The presence or absence of the alkyne group plays a crucial role in determining the electron density of the gold core, leading to different pathways for nucleophilic or electrophilic attacks and subsequent transformations.