Nitron-derivative-based palladium carbene complexes: structural characterization, theoretical calculations, and catalytic applications in the Mizoroki-Heck coupling reaction

New palladium(0) and palladium(ii) complexes with N-heterocyclic carbene (NHC) ligands derived from nitron and its derivatives were synthesized. The structures of most of these complexes were established by single-crystal X-ray diffraction studies. Among the new complexes, the palladium complex with a monodentate NHC ligand derived from nitron demonstrated the highest efficacy as a catalyst precursor in the Mizoroki-Heck coupling reaction of aryl chlorides with alkenes. Theoretical calculations provide valuable insights into the electronic parameters of both the ligands and the palladium complexes, highlighting the significance of a robust Pd-C bond and the & pi;-accepting property of the NHC ligand in achieving enhanced catalytic activity. Notably, catalyst activation occurred much more rapidly with the preformed palladium(0) complex compared to its palladium(ii) counterpart. Palladium(0) NHC complexes, obtained from nitron and its derivatives, exhibited high efficacy in catalyzing the Mizoroki-Heck coupling reaction involving aryl chlorides.

Automated summary

New palladium complexes with N-heterocyclic carbene (NHC) ligands derived from nitron and its derivatives were synthesized and their structures were determined by X-ray diffraction. Among these complexes, the palladium complex with a monodentate NHC ligand derived from nitron showed the highest catalytic activity in the Mizoroki-Heck coupling reaction. Theoretical calculations explained the importance of a robust Pd-C bond and the π-accepting property of the NHC ligand for enhanced catalytic activity. Notably, the activation of the preformed palladium(0) complex was much faster compared to its palladium(II) counterpart. Palladium(0) NHC complexes obtained from nitron and its derivatives exhibited high efficacy in catalyzing the Mizoroki-Heck coupling reaction involving aryl chlorides.