Gold–Ligand-Catalyzed Selective Hydrogenation of Alkynes into cis-Alkenes via H₂ Heterolytic Activation by Frustrated Lewis Pairs

Abstract

The selective hydrogenation of alkynes to alkenes is an important synthetic process in the chemical industry. It is commonly accomplished using palladium catalysts that contain surface modifiers, such as lead and silver. Here we report that the adsorption of nitrogen-containing bases on gold nanoparticles results in a frustrated Lewis pair interface that activates H 2 heterolytically, allowing an unexpectedly high hydrogenation activity. The so-formed tight-ion pair can be selectively transferred to an alkyne, leading to a cis isomer; this behavior is controlled by electrostatic interactions. Activity correlates with H 2 dissociation energy, which depends on the basicity of the ligand and its reorganization on activation of hydrogen. High surface occupation and strong Au atom−ligand interactions might affect the accessibility and stability of the active site, making the activity prediction a multiparameter function. The promotional effect found for nitrogen-containing bases with two heteroatoms was mechanistically described as a strategy to boost gold activity.

Design of Single Gold Atoms on Nitrogen‐Doped Carbon for Molecular Recognition in Alkyne Semi‐Hydrogenation

“…[13] Thesingle-atom catalyst Au/AC-413 shows approximately three-fold higher activity than the rest Au/ACs amples containing mainly Au nanoparticles.O n the other hand, the two substrates display strikingly different catalytic responses on the Au/NC-T series.W hile the 1hexyne hydrogenation activity is independent on the activation temperature and consequent Au speciation, av olcanolike curve is observed in the case of 2-methyl-3-butyn-2-ol. In accordance with the literature reports, [14] all these gold systems give essentially full selectivity to the aimed alkenes. In addition, HAADF-STEM examination on the two extreme Au/NC-T catalysts confirmed that the atomic dispersion of gold remains unaltered after the hydrogenation performance ( Figure S10).…”

A Durable Nickel Single‐Atom Catalyst for Hydrogenation Reactions and Cellulose Valorization under Harsh Conditions

“…Thea ctivation barrier for this step is 0.58 eV (DH), which is 0.87 eV lower than that on Au(111) surface. [19] Theelectron density difference of TS1 (Figure 3c)s hows as ignificant electron density decrease on H d+ and an increase on H dÀ .From the ELF and LOL maps the covalent interaction between Na nd H d+ is clearly seen, and the high localization of electron density around H dÀ and delocalization between H dÀ and Ni are also observed. Consequently,t he H 2 molecule is heterolytically dissociated to form a meta-stable H d+ -N and H dÀ -Ni configuration (Figure 3b;S upporting Information, Figure S13).…”

A Durable Nickel Single‐Atom Catalyst for Hydrogenation Reactions and Cellulose Valorization under Harsh Conditions

“…It can be viewed as the coordination exchange of the pyridine ligand and hydrogen atom during H 2 activation. The activation barrier for this step is 0.58 eV (Δ H ), which is 0.87 eV lower than that on Au(111) surface . The electron density difference of TS1 (Figure c) shows a significant electron density decrease on H δ+ and an increase on H δ− .…”