Synthesis, structure and catalysis of a NHC-Pd(II) complex based on a tetradentate mixed ligand

摘要

Bis-benzimidazolium salt (S)-2,2'-bis[2''-(N-picolyl-benzimidazoliumyl) ethoxy]-1,1'-binaphthyl hexafluorophosphate [(S)-LH2]center dot(PF6)(2) and its NHC palladium(II) complex [(S)-LPd](PF6)(2) (1) have been prepared and characterized. Complex 1 is formed by one tetradentate mixed ligand (S)-L and one Pd(II) ion, in which one 15-membered ring and two 6-membered rings are present. In this complex, intramolecular pi-pi interactions between naphthalene rings and benzimidazole rings are observed. Additionally, the catalytic activity of complex 1 in three types of C-C coupling reactions (Suzuki-Miyaura, Heck-Mizoroki and Sonogashira reactions) was investigated. The results show that complex 1 is an effective catalyst in these coupling reactions.