Insights into the Active Catalyst Formation from Dinuclear Palladium Acetate in Pd-Catalyzed Coupling Reactions: A DFT Study

Abstract

We studied the steps in the formation of active palladium catalyst species from palladium acetate dimer employing density functional theory calculations. We explored the possible pathways with an automated reaction search and studied the kinetics with stochastic simulation analysis. The dimeric form of palladium acetate is considered a resting state of the catalyst. Our reaction search starting from the dimeric form by sequential ligand addition resulted in experimentally observed monomeric species. We analyzed the bonding in the palladium acetate dimer and the role of Pd in the stability of the dimeric species. We implemented the Gillespie stochastic simulation algorithm to gain more insights into multichannel reaction paths and applied it to the degradation pathways. The analysis of the thermodynamic and kinetic data for these degradation pathways suggests that the dimeric form of the catalyst can be a potential catalytic precursor in the palladium acetate-catalyzed coupling reactions under the experimental reaction conditions.

Synthesis of Vinyl Acetate Monomer Over PdCu Alloys: The Role of Surface Oxygenation in the Reaction Path

“…The results of in situ DRIFT, in combination with catalyst characterization, provide support for the reaction mechanism proposed by Stacchiola et al, [61,71,73] This mechanism involves ethylene and AcOH coupling steps that are favored by oxygenated surface groups and terminal hydroxyl groups. These findings are consistent with the results of Augustine et.al, [89,90] which suggest that vinyl acetate-hydrated intermediates are present in the same region of Pd(AcOH) surface intermediates.…”

“…Figure 4 displays the DRIFT spectra of the reaction on the PCZT and PCZA catalysts at 200 °C, along with the deconvolution regions.Figure4displays the DRIFTS results at 200 °C, which suggests that the surface intermediates resulting from the ethylene and acetic acid moved over the surface, as suggested by Jacobs et al[61] Indeed, the PCZT catalyst exhibited a lower proportion of the surface intermediates of hydrogenated VAM, whereas the PCZA catalyst the stretching corresponding to CO 2 , suggesting predominant combustion of acetic acid (Figure4c). Noteworthy is that the PCZT catalyst prevents the CO 2 adsorption [19].…”

Bringing a Mechanistic Lens to the Development of New Transfer Hydroarylation Isodesmic Reactions for the Synthesis of Amides, Thioamides, Amidines, Alkenes and Ketones from Carboxylic Acids via Extrusion and Insertion Elementary Steps

“…Palladium carboxylates, which are the key precursors to decarboxylation, are well established species in inorganic chemistry. For example, palladium acetate and palladium trifluoroacetate are both readily available from a wide range of chemical suppliers and these are widely used as precatalysts [116,117] …”

“…For example, palladium acetate and palladium trifluoroacetate are both readily available from a wide range of chemical suppliers and these are widely used as precatalysts. [116,117] Carboxylates can bind to palladium centers via a number of coordination modes (Figure 1A). [118] For mononuclear complexes, they can bind in a k 2 -bidentate, (1) or k 1monodentate, 2, fashion, while a number of bridging binding modes are known in dinuclear and polynuclear palladium carboxylate complexes (e. g. 3).…”