TY - JOUR

T1 - Modeling Key Pathways Proposed for the Formation and Evolution of “Cocktail”-Type Systems in Pd-Catalyzed Reactions Involving ArX Reagents

AU - Polynski, Mikhail V.

AU - Ananikov, Valentine P.

PY - 2019

Y1 - 2019

N2 - 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] n L species, and (3) the pool of irreversibly deactivated Pd. Stabilization by ArX oxidative addition, coordination of base species, and binding of X - anions 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 reactivation, 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.

AB - 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] n L species, and (3) the pool of irreversibly deactivated Pd. Stabilization by ArX oxidative addition, coordination of base species, and binding of X - anions 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 reactivation, 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.

KW - DFT modeling

KW - Pd halides

KW - Pd leaching

KW - Pd nanoparticles

KW - aryl halides

KW - catalyst evolution

KW - cross-coupling catalysts

KW - oxidative addition

UR - http://www.scopus.com/inward/record.url?scp=85064351444&partnerID=8YFLogxK

U2 - 10.1021/acscatal.9b00207

DO - 10.1021/acscatal.9b00207

M3 - Article

VL - 9

SP - 3991

EP - 4005

JO - ACS Catalysis

JF - ACS Catalysis

SN - 2155-5435

IS - 5

ER -