The n1-allyl platinum and palladium cationic complexes tridentate neutral pincer ligand [(PNP)M(n1-CH2CH=CHR1)]+ (1, PNP = 2,6-bis-diphenylphosphinomethylpyridine) undergo intermol. attack of the terminal gamma-carbon atom of the allyl system at the coordinated olefin of dicationic platinum and palladium complexes [(PNP)M(n2-CH2=CHR)]2+ (2), producing binuclear species [(PNP)M(n2:n1-CH2=CHCHR1CHRCH2)M(PNP)]3+ (4), in which the metal formerly p-coordinated becomes s-bonded, and the metal formerly s-bonded becomes p-coordinated. The reaction can be run catalytically with respect to the addn. of ethylene to a n1-allyl complex, using the dicationic ethylene complex as catalyst
