Isomeric Palladium Complexes Bearing Imidazopyridine-Based Abnormal Carbene Ligands: Synthesis, Characterization, and Catalytic Activity in Direct C-H Arylation Reaction

Yan Yi Lee, Han Wei Zseng, Zong Han Tsai, Yong Siang Su, Ching-Han Hu, Hon Man Lee

Research output: Contribution to journalArticle

2 Citations (Scopus)

Abstract

A series of "abnormal" NHC ligand precursors based on imidazopyridines and their corresponding NHC-palladium diiodide complexes were prepared. Our study included the first report on a palladium complex with an abnormal NHC ligand derived from imidazo[1,5-a]pyridine. DFT calculation on the free ligands confirmed the higher electron-donating properties of the abnormal NHC ligands than their normal NHC isomers. The structural properties of all the complexes were studied in detail by single-crystal X-ray diffraction studies, revealing that, in general, Pd-carbene bond distances in palladium complexes with abnormal NHCs were longer than those in their isomers with normal NHCs. A significant trans influence is observed in the palladium complexes with abnormal NHC ligands. But in the complexes with normal NHC ligands, both Pd-carbene and Pd-N bond distances are short. Catalytic studies revealed that the palladium complexes were very efficient in catalyzing direct C-H arylation between 1,2-dimethylimidazole and aryl halides using a low Pd loading of 0.5 mol %. The difference in catalytic activity between the normal and abnormal isomers is, however, small.

Original languageEnglish
Pages (from-to)805-815
Number of pages11
JournalOrganometallics
Volume38
Issue number4
DOIs
Publication statusPublished - 2019 Feb 25

Fingerprint

Bearings (structural)
Palladium
carbenes
catalytic activity
palladium
Catalyst activity
Ligands
ligands
synthesis
Isomers
isomers
Discrete Fourier transforms
halides
carbene
Structural properties
pyridines
Single crystals
X ray diffraction
Electrons
single crystals

All Science Journal Classification (ASJC) codes

  • Physical and Theoretical Chemistry
  • Organic Chemistry
  • Inorganic Chemistry

Cite this

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title = "Isomeric Palladium Complexes Bearing Imidazopyridine-Based Abnormal Carbene Ligands: Synthesis, Characterization, and Catalytic Activity in Direct C-H Arylation Reaction",
abstract = "A series of {"}abnormal{"} NHC ligand precursors based on imidazopyridines and their corresponding NHC-palladium diiodide complexes were prepared. Our study included the first report on a palladium complex with an abnormal NHC ligand derived from imidazo[1,5-a]pyridine. DFT calculation on the free ligands confirmed the higher electron-donating properties of the abnormal NHC ligands than their normal NHC isomers. The structural properties of all the complexes were studied in detail by single-crystal X-ray diffraction studies, revealing that, in general, Pd-carbene bond distances in palladium complexes with abnormal NHCs were longer than those in their isomers with normal NHCs. A significant trans influence is observed in the palladium complexes with abnormal NHC ligands. But in the complexes with normal NHC ligands, both Pd-carbene and Pd-N bond distances are short. Catalytic studies revealed that the palladium complexes were very efficient in catalyzing direct C-H arylation between 1,2-dimethylimidazole and aryl halides using a low Pd loading of 0.5 mol {\%}. The difference in catalytic activity between the normal and abnormal isomers is, however, small.",
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Isomeric Palladium Complexes Bearing Imidazopyridine-Based Abnormal Carbene Ligands : Synthesis, Characterization, and Catalytic Activity in Direct C-H Arylation Reaction. / Lee, Yan Yi; Zseng, Han Wei; Tsai, Zong Han; Su, Yong Siang; Hu, Ching-Han; Lee, Hon Man.

In: Organometallics, Vol. 38, No. 4, 25.02.2019, p. 805-815.

Research output: Contribution to journalArticle

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AU - Su, Yong Siang

AU - Hu, Ching-Han

AU - Lee, Hon Man

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