Dinuclear N-heterocyclic carbene palladium(II) complexes as efficient catalysts for the Buchwald–Hartwig amination

Abstract

A series of dinuclear N-heterocyclic carbene (NHC) palladium complexes [PdCl2(NHC)]2(μ-L) (1–6, L = diphosphine ligands) has been synthesized and fully characterized by 1H NMR, 13C NMR and 31P NMR spectroscopies, elemental analysis, IR spectroscopy, and X-ray crystal structural study. The solid-state structures of 1–6 show dinuclear frameworks with two palladium(II) centres were held together by bridging diphosphine ligands. Each palladium centre was coordinated by an N-heterocyclic carbene ligand, a phosphorus atom and two chloro ions in a trans-arrangement. Further explorations of the catalytic potential of the dinuclear carbene palladium complexes as catalysts for Pd-mediated transformations have been examined under microwave irradiation conditions and the title complexes (1–6) displayed good catalytic activities in Buchwald–Hartwig aminations of aryl chlorides.