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Updated: Jun 10, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Experimental Evidence for Zerovalent Pd(NHC) as a Competent Catalyst in C-N Cross-Coupling (NHC = DiMeIHeptCl)
Volodymyr Semeniuchenko1,2, Sepideh Sharif3, Neha Rana3
1Centre for Catalysis Research and Innovation (CCRI), Department of Chemistry and Biomolecular Sciences, University of Ottawa, Ottawa, Ontario K1N 6N5, Canada.
The novel DiMeIHeptCl ligand stabilizes key palladium intermediates for C-N cross-coupling reactions. This research details the isolation and characterization of these stable palladium complexes, advancing catalytic chemistry.
Area of Science:
- Organometallic Chemistry
- Catalysis
Background:
- Palladium-catalyzed C-N cross-coupling reactions are crucial in organic synthesis.
- Stabilization of reactive palladium intermediates is essential for efficient catalysis.
Purpose of the Study:
- To synthesize and characterize novel palladium-N-heterocyclic carbene (NHC) complexes.
- To investigate the role of a sterically demanding NHC ligand in stabilizing palladium intermediates for C-N cross-coupling.
Main Methods:
- Synthesis and structural characterization of palladium complexes using the DiMeIHeptCl ligand.
- Isolation and characterization of zerovalent and divalent palladium intermediates.
- Investigation of catalyst activation pathways and oxidative addition.
Main Results:
- Isolation and structural characterization of stable zerovalent palladium complexes ([Pd(DiMeIHeptCl)]2(μ-N2), [Pd(DiMeIHeptCl)]2(μ-η2-1,2-η2-4,5-C6H6), Pd(DiMeIHeptCl)(pyridine)).
- Isolation and characterization of divalent palladium complexes (PdCl(Ph)(DiMeIHeptCl), PdCl(Ph)(DiMeIHeptCl)(n-propylamine)).
- A 14-electron Pd complex demonstrated exceptional stability due to dispersion interactions.
Conclusions:
- The branched NHC ligand DiMeIHeptCl effectively stabilizes reactive palladium intermediates.
- Understanding these intermediates provides insights into catalyst activation mechanisms for Pd-catalyzed C-N cross-coupling.
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