Intermolecular Cross-coupling Between η2-Olefin and η1-Allyl Ligands in Cationic Platinum(II) and Palladium(II) Complexes

The terminal (gamma) carbon atom of the allyl system in eta(1)-allyl platinum and palladium complexes of the tridentate pincer ligand PNP (PNP = 2,6-bis-diphenylphosphinomethylpyridine) attacks the coordinated olefin of dicationic platinum and palladium complexes with the same ligand, producing binuclear species in which the metal formerly pi-coordinated becomes sigma-bonded, and the metal formerly sigma-bonded becomes pi-coordinated. The reaction can be run catalytically with respect to the addition of ethylene to a eta(1)-allyl complex, using the dicationic ethylene complex as catalyst.