A DFT Insight into Hashmi Phenol Synthesis Catalyzed by M₆@Au₃₂ (M=Ag, Cu, Pd, Pt, Ru, Rh) Core–Shell Nanoclusters

Abstract

The Hashmi phenol synthesis reaction (the ω‐alkynylfuran cycloisomerization) catalyzed by the M6@Au32 (M=Ag, Cu, Pd, Pt, Ru, and Rh) core–shell nanoclusters was investigated systematically. The 5‐exo Friedel–Crafts‐type mechanism of the ω‐alkynylfuran cycloisomerization on the six core–shell nanoclusters was analyzed in details. The adsorption property and catalytic activity of the Au38 nanocluster could be effectively tuned by the substitution of the core Au atoms. The adsorption properties of alkynes on core–shell and Au38 clusters depended on four factors, including the numbers of unoccupied and occupied d orbitals, orientation of d orbital and d‐bonding down‐shift. Compared with the Au38 cluster, the core–shell nanoclusters could cause larger changes in the interaction energies between the substrate and cluster fragments, which are beneficial for facilitating the cyclization step and the ring closing of the dienone carbene–gold intermediate. In addition, according to the calculated results, the catalytic activity of Au38 can be tuned by substitution of the core gold atoms.

Theoretical insights into ω-alkynylfuran cycloisomerisation catalyzed by Au/CeO2(111): the role of the CeO2(111) support

“…4-7, the rate-limiting step of the 5-exo FCT reaction route in the gas phase is the nucleophilic addition of the Cb atom to the C1 site of the furan ring to form the spiro-intermediate IM2, which has an energy barrier of 13.66 kcal mol À1 , while the formation of IM4 is the rate-determining step in acetonitrile. However, for the DDA pathway, the formation of the b-alkenylated furan and the 6-endo FCT pathway, the energy barriers of the rate-limiting steps are 46 On the basis of our previous reports [37][38][39] and the above discussions, the 5-exo Friedel-Cras-type mechanism (FCT) is the most feasible pathway for u-alkynylfuran cycloisomerisation. Accordingly, the 5-exo FCT mechanism of u-alkynylfuran cycloisomerisation on the various reaction sites of Au 10 / CeO 2 (111) and Au 11 /CeO 2 (111) were investigated.…”

“…Herein, u-alkynylfuran cycloisomerisation catalyzed by CeO 2 -supported gold nanoparticles (Au 3 , Au 4 , Au 10 , Au 11 ) is explored with the help of density functional theory (DFT), as an expansion of our prior research. [37][38][39] Gold nanoparticles (Au 3 , Au 4 , Au 10 , Au 11 ) were employed for consistence with experimental results reported by Oliver-Meseguer et al and others. [40][41][42] In these studies, it was found that small gold clusters (only 3 to 10 atoms in size) can be formed during the catalytic processes, which can catalyze the ualkynylfuran cycloisomerisation reaction.…”

“…The 5-exo Friedel-Cras-type mechanism (FCT) is the most feasible pathway of u-alkynylfuran cycloisomerisation to produce the targeted phenol derivative product, catalyzed by subnanometer gold clusters and planar gold clusters, based on our previous reports. [37][38][39] In order to illustrate the catalytic role of the supporting material, stoichiometric CeO 2 and partially reduced CeO 2 with one vacancy are also considered here. In addition, the possible catalytic sites of Au n /CeO 2 (111), including the atop, edge and interface sites, are investigated, aiming to illustrate the catalytic activity of the catalytic sites and interfacial effects.…”