Coordinated olefins as incipient carbocations: catalytic codimerization of ethylene and internal olefins by a dicationic Pt(II)-ethylene complex.

The coordinated ethylene molecule in the dicationic complex [(PNP)Pt(CH2=CH2)](BF4)2 (PNP = 2,6-bis(diphenylphosphinomethyl)pyridine) undergoes nucleophilic attack by free internal alkenes, giving the isolable complexes [(PNP)Pt(CH2=CHCH(Me)CMeRR'](BF4)2 (R, R' = H, Me) and providing a new effective pathway for a chemo- and regio-selective catalytic hydrovinylation reaction.