Robust and electron-rich cis-palladium(II) complexes with phosphine and carbene ligands as catalytic precursors in Suzuki coupling reactions

Chuang Yi Liao, Kai Ting Chan, Cheng Yi Tu, Yu Wei Chang, Ching Han Hu, Hon Man Lee

Research output: Contribution to journalArticle

56 Citations (Scopus)

Abstract

A new imidazolinium ligand precursor [L2H]Cl (2) was prepared in 86 % yield. Compared with its imidazolium counterpart, [L1H]Cl (1), 2 is very sensitive to moisture and can undergo ring-opening reactions very readily. Palladium complexes with the ring-opened products from imidazolinium salts were isolated and characterized by X-ray crystallography. Theoretical studies confirmed that the imidazolinium salt has a higher propensity for the ring-opening reaction than the imidazolium counterpart. New mixed phosphine/carbene palladium complexes, Cis-[PdCl2(L)(PR3)] (L = L1 and L2; R = Ph. Cy). were successfully prepared. These complexes are highly robust as revealed by variable-temperature NMR spectroscopic studies and thermal gravimetric analysis. The structural and electronic properties of the new complexes on varying the carbene group (imidazol-2-ylidene group (unsaturated carbene) vs. imidazolin-2-ylidene (saturated carbene)) and the phosphine group (PPh3 vs. PCy 3) were studied in detail by X-ray crystallography, X-ray photoelectron spectroscopy, and theoretical calculations. The catalytic study reveals that Cis-[PdCl2(L2)-(PCy3)] is a competent PdII precatalyst for Suzuki coupling reactions, in which unreactive aryl chlorides can be applied as substrates.

Original languageEnglish
Pages (from-to)405-417
Number of pages13
JournalChemistry - A European Journal
Volume15
Issue number2
DOIs
Publication statusPublished - 2009 Jan 2

All Science Journal Classification (ASJC) codes

  • Catalysis
  • Organic Chemistry

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