Conversion of Pd() off-cycle species into highly efficient cross-coupling catalysts

We report on the facile conversion of [Pd 2 (μ-Cl)(μ-η 3 -R-allyl)(NHC) 2 ] complexes, which are commonly considered undesirable off-cycle species in cross-coupling reactions, into active [PdCl(μ-Cl)(NHC)] 2 pre-catalysts. All reactions proceed under mild conditions (40 °C, 1-2 hours in acetone) usi...

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Published inDalton transactions : an international journal of inorganic chemistry Vol. 5; no. 16; pp. 542 - 5427
Main Authors Liu, Yaxu, Voloshkin, Vladislav A, Scattolin, Thomas, Cavallo, Luigi, Dereli, Busra, Cazin, Catherine S. J, Nolan, Steven P
Format Journal Article
LanguageEnglish
Published England Royal Society of Chemistry 28.04.2021
Subjects
Acetone
Catalysis
Catalysts
Chemical reactions
Conversion
Cross coupling
Dimers
NMR
Nuclear magnetic resonance
Oxidizing agents
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Summary:We report on the facile conversion of [Pd 2 (μ-Cl)(μ-η 3 -R-allyl)(NHC) 2 ] complexes, which are commonly considered undesirable off-cycle species in cross-coupling reactions, into active [PdCl(μ-Cl)(NHC)] 2 pre-catalysts. All reactions proceed under mild conditions (40 °C, 1-2 hours in acetone) using inexpensive HCl as both an oxidant and chloride source. DFT calculations were performed to explore the possible mechanism of this transformation, which appears to involve a combination of two different pathways. Moreover this study provides insights into factors favoring and hindering Pd( i ) dimer formation undesirable in catalysis. A simple and eco-friendly protocol to convert off-cycle Pd( i ) dimeric species into catalytically active air and moisture stable [Pd(NHC)Cl 2 ] 2 is presented.
Bibliography:Dedicated to the memory of Professor Victor Snieckus.
10.1039/d1dt00929j
Electronic supplementary information (ESI) available: Synthetic procedures, NMR spectra and computational data. See DOI
ObjectType-Article-1
SourceType-Scholarly Journals-1
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ISSN:1477-9226
1477-9234
DOI:10.1039/d1dt00929j