Facile and Efficient Olefination of Aryl Halides Catalyzed by a Palladium Complex Containing a Heteroarene-Functionalized N-Heterocyclic Carbene

[Ag 4 (L) 4 ](PF 6 ) 4 and [Pd(L) 2 ](PF 6 ) 2 (L = 3-(2,4-dimethyl-1,8-naphthyrid-7-yl)-1-picolylimidazolylidene) have been prepared and fully characterized. The silver compound consists of a Ag 4 ring with short Ag−Ag contacts displaying a butterfly conformation. The palladium complex exhibits a helical structure with palladium located in a square-planar environment with two carbene ligands and two pyridines in a cis arrangement. The palladium complex has proven to be a highly efficient catalyst for Heck coupling reactions of aryl bromides with n -butyl acrylate. TON values up to 10 6 and TOF values up to 5 × 10 5 h −1 can be achieved.