Synthesis, crystal structures and catalytic activities of palladium complexes with coumarin-functionalised N-heterocyclic carbene ligands

Abstract

In this contribution, we synthesized five new coumarin-functionalised PEPPSI type Pd-NHC complexes in order to examine their catalyst properties. The complexes were synthesized by the reaction of PdCl2 and corresponding benzimidazolium chloride in pyridine in the presence of excess amount of K2CO3. The structures of complexes were fully characterised using NMR and IR spectroscopy, elemental analyses and X-ray diffraction analyses. Crystal structures of four complexes revealed that they have slightly distorted square-planar geometry. Catalytic activities of complexes were tested in Suzuki-Miyaura reaction of phenylboronic acid and aryl bromide derivatives in H2O-DMF solvent system.