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Updated: Nov 26, 2025

Palladium N-Heterocyclic Carbene Complexes: Synthesis from Benzimidazolium Salts and Catalytic Activity in Carbon-carbon Bond-forming Reactions
Published on: July 30, 2017
Urea-Substituted Tetramethylcyclopentadienyl Ligands for Supramolecularly Accelerated RhIII -Catalyzed ortho-C-H
David Maurer1, Bernhard Breit1
1Institut für Organische Chemie, Albert-Ludwigs-Universität Freiburg, Albertstraße 21, 79104, Freiburg, Germany.
Abstract:
The design and synthesis of air-stable and conveniently crystallizable RhIII -cyclopentadienyl catalysts substituted with a urea moiety, which are able to accelerate the C-H olefination of benzoic acid derivatives, is reported. Through kinetic studies and NMR titration experiments, the catalysts' substrate recognition ability mediated by hydrogen bonding was identified to be the reason for this effect. Introduction of pyridone-phosphine ligands capable of forming additional H-bond interactions increased the catalytic performance even further. By unveiling a proportionality between reaction rate and relative complex formation enthalpy the hypothesis of a supramolecular catalyst preformation was supported. Its application to a variety of substrates proved the catalyst system's advantages, generally increasing the yields when compared to the results obtained with widely used [RhCp*Cl2 ]2 .
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