Superior Catalytic Outcomes of Dinuclear Palladium(II) NHC/PCy Complex Over Its Mononuclear Counterpart in Intermolecular α-Arylation of Amide.

Cooperation between metal centers appeared to be beneficial in many catalytic transformations when the metal centers are placed on a properly designed poly-NHC ligand platform. However, examples of such NHC ligand platforms are limited. Dinuclear palladium(II) complexes comprising bis-imidazolylidene along with pyridine or tricyclohexylphosphine (PCy) as ancillary ligands were synthesized and characterized by using standard spectroscopic techniques. The dinuclear bis-NHC complex with PCy as an ancillary ligand appeared to be a highly active precatalyst for the intermolecular α-arylation of 1-methyl-2-oxindole and this complex appeared to be beneficial over its corresponding mononuclear complex in terms of catalytic outcomes which is possibly due to the cooperative action between two palladium(II) centers during catalysis. The DLS measurements were performed which indicates the homogeneous nature of the aforementioned catalysis.