Palladium(II) Complexes with Benzimidazolin-2-ylidene and Phosphane Ligands and their Catalytic Activity in Mizoroki-Heck Coupling Reactions


Tuerkmen H. , PAPE T., HAHN F. E. , CETINKAYA B.

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, ss.285-294, 2009 (SCI İndekslerine Giren Dergi) identifier identifier

  • Basım Tarihi: 2009
  • Doi Numarası: 10.1002/ejic.200800948
  • Dergi Adı: EUROPEAN JOURNAL OF INORGANIC CHEMISTRY
  • Sayfa Sayıları: ss.285-294

Özet

Symmetrically and unsymmetrically substituted benzimidazolium bromides (1a-d = NHC center dot HBr) were synthesized, incorporating bulky benzyl and/or methoxyethyl substituents (a: R = pentamethylbenzyl, R' = 2-methoxyethyl; b: R = 2,3,5,6-tetramethylbenzyl, R' = methoxyethyl; c: R, R' = pentamethylbenzy]; d: R, R' = 2,3,5,6-tetramethylbenzyl). The salts were used to prepare NHC palladium complexes. Reaction of 1a-d with Pd(OAC)(2) and NaBr in d 1:1:3 ratio in dmso gave mono or dinuclear, bromide-bridged complexes of type 2. Complexes of type 2 react with monodentate or bidentate phosphanes in CH2Cl2 to afford the mixed benzimidazolin-2-ylidene-phosphane complexes 3-6. Reaction of salts 1a-d with Pd(OAc)(2) in a 1:2 ratio, in the absence of NaBr, gave complexes trans-[PdBr2(NHC)(2)] (7). All compounds were fully characterized by NMR spectroscopy, mass spectrometry (MALDI), and elemental analysis. In addition, the molecular structures of 2c, 3c, 3d, and 5b were determined by X-ray diffraction. The catalytic activities of 2-7 in Mizoroki-Heck C-C coupling reactions of aryl halides with n-butyl acrylate are described and compared. ((C) Wiley-VCH Verlag GmbH & Co, KGaA, 69451 Weinheim, Germany, 2009)