Pd–PEPPSI-Type Expanded Ring N‑Heterocyclic Carbene Complexes: Synthesis, Characterization, and Catalytic Activity in Suzuki–Miyaura Cross Coupling

The synthesis and characterization of the new six- and seven-membered Pd–PEPPSI-type N-heterocyclic carbene (NHC) complexes 3 and 4 is described. Complexes of the general formula [Pd­(NHC)­(3ClPy)­Cl2] (NHC = 6- or 7-Mes, 3ClPy = 3-chloropyridine) are accessed via the oxidation of the well-defined parent palladium(0) complexes 1 and 2. Complexes 3 and 4 have been employed in Suzuki–Miyaura cross-coupling and catalytic dehalogenation of a range of aryl halide substrates.