Modeling Key Pathways Proposed for the Formation and Evolution of “Cocktail”-Type Systems in Pd-Catalyzed Reactions Involving ArX Reagents

Mikhail Polynskii, Valentine P. Ananikov

Research output: Contribution to journalArticleScientificpeer-review

18 Citations (Scopus)
67 Downloads (Pure)

Abstract

Reversible leaching of palladium nanoparticles occurs in a variety of catalytic reactions including cross-couplings, amination, the Heck reaction, etc. It is complemented by capturing of soluble palladium species on the surface of nanoparticles and de novo formation of nanoparticles from Pd precatalysts. We report here a detailed computational study of leaching/capture pathways and analysis of related stabilization energies. We demonstrate the validity of the "cocktail-of-species" model for the description of Pd catalysts in ArX oxidative addition-dependent reactions. Three pools of Pd species were evaluated, including (1) the pool of catalytically active Pd nanoparticles with a high concentration of surface defects, (2) the pool of monomeric and oligomeric L[ArPdX]<sub>n</sub>L species, and (3) the pool of irreversibly deactivated Pd. Stabilization by ArX oxidative addition, coordination of base species, and binding of X<sup>−</sup> anions (derived from salt additives) were found to be crucial for "cocktail"-type systems, and the corresponding reaction energies were estimated. An inherent process of ArX homocoupling, leading to the formation of Pd halides that require re-activation, was considered as well. The pool of irreversibly deactivated Pd comprises nanoparticles with (1 1 1) and (1 0 0) facets and Pd in the bulk form. The study is based on DFT modeling and specifies the role of Pd nanoparticles in (quasi )homogeneous coupling reactions involving ArX reagents.
Original languageEnglish
Pages (from-to)3991-4005
Number of pages15
JournalACS Catalysis
Volume9
Issue number5
DOIs
Publication statusPublished - 2019

Keywords

  • aryl halides
  • catalyst evolution
  • cross-coupling catalysts
  • DFT modeling
  • oxidative addition
  • Pd halides
  • Pd leaching
  • Pd nanoparticles

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