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- Title
Ionic Pd/NHC Catalytic System Enables Recoverable Homogeneous Catalysis: Mechanistic Study and Application in the Mizoroki–Heck Reaction.
- Authors
Eremin, Dmitry B.; Denisova, Ekaterina A.; Yu. Kostyukovich, Alexander; Martens, Jonathan; Berden, Giel; Oomens, Jos; Khrustalev, Victor N.; Chernyshev, Victor M.; Ananikov, Valentine P.
- Abstract
N‐Heterocyclic carbene (NHC) ligands are ubiquitously utilized in catalysis. A common catalyst design model assumes strong M–NHC binding in this metal–ligand framework. In contrast to this common assumption, we demonstrate here that lability and controlled cleavage of the M−NHC bond (rather than its stabilization) could be more important for high‐performance catalysis at low catalyst concentrations. The present study reveals a dynamic stabilization mechanism with labile metal–NHC binding and [PdX3]−[NHC‐R]+ ion pair formation. Access to reactive anionic palladium intermediates formed by dissociation of the NHC ligands and plausible stabilization of the molecular catalyst in solution by interaction with the [NHC‐R]+ azolium ion is of particular importance for an efficient and recyclable catalyst. These ionic Pd/NHC complexes allowed for the first time the recycling of the complex in a well‐defined form with isolation at each cycle. Computational investigation of the reaction mechanism confirms a facile formation of NHC‐free anionic Pd in polar media through either Ph–NHC coupling or reversible H–NHC coupling. The present study formulates novel ideas for M/NHC catalyst design.
- Subjects
HECK reaction; HOMOGENEOUS catalysis; CARBENES; ION pairs; ELECTROSPRAY ionization mass spectrometry; CATALYSTS recycling
- Publication
Chemistry - A European Journal, 2019, Vol 25, Issue 72, p16564
- ISSN
0947-6539
- Publication type
Article
- DOI
10.1002/chem.201903221