Heteropolymetallic Complexes Linked to a 9,10-Dihydroanthracenyl Frame. Ruthenium as Active Spectator for Palladium Reactivity

New monometallic Pd­(II) (3, 4) and heteropolymetallic Pd­(II)/Ru­(II) complexes (5, 6) linked to an original 9,10-dihydroanthracenyl–pyrrolidine scaffold were synthesized and fully characterized. For monometallic complexes, exo-3 and endo-4 conformers were exclusively obtained from Pd­(OAc)₂ and [PdCl₂(COD)], respectively. The formation of the sterically hindered endo-4 was justified by the positive noncovalent intramolecular Cl−π interaction, observed by X-ray diffraction. The reaction of endo-4 with 1 and 2 equiv of [RuCp­(NCMe)₃]­PF₆ led to complexes 5 and 6, respectively. It is worth noting that lower conversions in the Suzuki–Miyaura coupling were found using 5 and 6 as catalysts, in comparison to those with monometallic palladium complexes. This behavior could be related to the higher stabilization of Pd­(II) species for the heteropolymetallic complexes, as proven by electrochemical analyses.