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

Abstract

Bis-benzimidazolium salt (S)-2,2′-bis[2′′-(N-picolyl-benzimidazoliumyl)ethoxy]-1,1′-binaphthyl hexafluorophosphate [(S)-LH₂]·(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 π–π 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.