Exploration of Formation and Size‐Evolution Pathways of Thiolate‐Gold Nanoclusters in the CO‐Directed [Au₂₅(SR)₁₈]⁻ Synthesis

Abstract

An intermolecular association and decarboxylation mechanism is proposed to understand the experimental evidence of the stepwise 2e− hopping in the reductant‐assisted thiolate‐gold cluster synthesis. Based on the newly proposed intermolecular reaction mechanism, a total of 19 molecular‐like reaction equations are deduced to account for the bottom‐up formation of 2e−–8e− gold nanoclusters in the CO‐directed [Au25(SR)18]− synthesis. With these established reaction equations, atomic pathways of three prototype cluster‐size evolution reactions are comprehensively explored in the course of [Au25(SR)18]− synthesis, namely, the conversion of 0e− homoleptic Au(I)‐SR complexes to the 2e− intermediate Au15(SR)13 cluster, the size‐evolution of 2e− Au15(SR)13 cluster to the 4e−–8e−cluster (stepwise 2e−‐hopping), and the isoelectronic addition reaction of [Au23(SR)16]− to the [Au25(SR)18]−. The studies reveal that the CO can combine with the Au(I)‐complex to form [Aux(SR)x‐COOH]− species in the alkaline condition, which acts as the active precursors in the 2e− hopping cluster‐size evolution process. Lastly, as a conceptual extension of the mechanistic studies of the CO‐reduction system, a similar intermolecular reaction mechanism is proposed for the 2e− reduction in the conventional “NaBH4 reduction” system.

Selective formation of [Au23(SPhtBu)17]0, [Au26Pd(SPhtBu)20]0 and [Au24Pt(SC2H4Ph)7(SPhtBu)11]0 by controlling ligand-exchange reaction

“…For such a geometric structure, formation of a core–shell structure with Pd as the core and Au as the shell typically dose not occur. Although the chemical composition of the final product is affected by the reaction path, 63,64 this geometric factor appears to be largely related to the fact that Au 27 Pd(SPh t Bu) 20 and Au 26 Pd 2 (SPh t Bu) 20 were not formed in our experiments.…”

Exploration of the Atomic Pathway of Seed-Mediated Growth from Icosahedral [Au25(SR)18]− to Bi-Icosahedral Au38(SR)24 and Au44(SR)26 Clusters Based on the 2e– Hopping Mechanism

“…Recently, our group proposed 18 stoichiometric equations to understand the 2e − hopping process in the bottom-up synthesis of the [Au 25 (SR) 18 ] − cluster. 18 The atomic pathway of formation of 2e − , 4e − , 6e − , and 8e − clusters as well as the conversion of facecentered cubic configuration [Au 23 (SR) 16 ] − to the icosahedral [Au 25 (SR) 18 ] − cluster was proposed. Our results indicated that a smaller size cluster can convert into a larger size cluster via a LaMer growth mechanism by carboxylation and decarboxylation reactions.…”

“…Our results indicated that a smaller size cluster can convert into a larger size cluster via a LaMer growth mechanism by carboxylation and decarboxylation reactions. 18 Furthermore, based on the "2e − -unit decomposition" strategy, it was possible to deduce the intermediate species and their structures involved in the size conversion process from one cluster to another cluster. 18 In this study, we carried out systematic theoretical study on the seed-mediated growth mechanism of gold clusters from 8e − [Au 25 (SR) 18 ] − to 14e − Au 38 (SR) 24 and then to the 18e − A u 4 4 ( S R ) 2 6 c l u s t e r .…”

“…We first theoretically predicted the structure of 10e − [Au 29 (SR) 20 ] − , 12e − [Au 33 (SR) 22 ] − , and 16e − Au 41 (SR) 25 clusters based on the "2e − -unit decomposition" strategy. 18 On the basis of the predicted intermediate structures, the 2e − hopping cluster growth pathway from [Au 25 (SR) 19,20 Au 38 (SR) 24 , 21 and Au 44 (SR) 26 22 was taken from the experimental crystal structures. The thiolate group (SR) was unified to 3-mercaptobenzoic acid (m-MBA, −SPhCOOH), in agreement with an experimental report.…”

“…29,36 Unfortunately, the exact atomic structure of two clusters remained unknown, although the two clusters were successfully isolated and characterized by the UV−Vis adsorption analysis. 29,36 Herein, we use our recently proposed "2e − -unit decomposition strategy" 18 to study the structure of 10e 39 and Au 32 (SR) 24 , 39 have been theoretically predicted. However, the predicted atomic packing configuration of these clusters is fcc configuration, which is poorly correlated with the icosahedral Au 25 and bi-icosahedron Au 38 clusters.…”