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Journal Articles Dalton Transactions Year : 2017

Dissimilar catalytic behavior of molecular or colloidal palladium systems with a new NHC ligand

Abstract

In this work, we describe the synthesis of a new N-heterocyclic carbene (NHC) ligand, derived from a hybrid pyrazole-imidazolium scaffold, namely 1-[2-(3,5-dimethylpyrazol-1-yl)ethyl]-3-((S)-1-phenylethyl)-3H-imidazol-2-ylidene (L). This ligand has been used as a stabilizer for the organometallic synthesis of palladium(0) nanoparticles (Pd NPs). L presents a better stabilizing effect than its pre-carbenic HLCl counterpart, allowing the formation of isolated Pd NPs while HLCl yields aggregated ones. Additionally, molecular Pd(ii) coordination compounds of L and HLCl were synthesized and characterized to better understand the coordination modes of these ligands. Both molecular and colloidal Pd systems have been further tested in catalytic C-C coupling processes. Three different types of reactions have been observed depending on the catalytic system: (i) the Suzuki-Miyaura reaction takes place with Pd molecular complexes; (ii) a secondary reaction, the dehalogenation of the substrate, is always detected and (iii) the C-C homocoupling between two molecules of bromoarenes is observed with colloidal catalysts.

Dates and versions

hal-01940897 , version 1 (30-11-2018)

Identifiers

Cite

Fernando Gomez-Villarraga, Jonathan de Tovar, Miguel Guerrero, Pau Nolis, T. Parella, et al.. Dissimilar catalytic behavior of molecular or colloidal palladium systems with a new NHC ligand. Dalton Transactions, 2017, 46 (35), pp.11768-11778. ⟨10.1039/C7DT02729J⟩. ⟨hal-01940897⟩
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