Synthesis, characterization and catalytic activity of novel N-heterocyclic carbene-palladium complexes.

The reaction of Pd(OAc)2 with 1-(benzhydryl)-3-(alkyl)benzimidazolium salts 1a-d yields trans-bis[1-(benzhydryl)-3-(alkyl)benzimidazolin-2-ylidene]dibromopalladium(II) complexes (2a-d) which were characterized by elemental analysis, NMR spectroscopy and the molecular structures of 2b, and 2d were determined by X-ray crystallography. The catalytic activity of PdBr2bis(benzimidazolin-2-ylidene) complexes 2a-d was evaluated in the direct arylation reaction of benzothiazole with bromobenzene derivatives.