Ethylene Polymerization by Palladium/Phosphine–Sulfonate Catalysts in the Presence and Absence of Protic Solvents: Structural and Mechanistic Differences

M. Kanazawa, S. Ito, K. Nozaki*
Organometallics 2011, 30, 6049–6052.  DOI: 10.1021/om2004207

Abstract: Ethylene polymerization catalyzed by palladium(II)/phosphine–sulfonate complexes was performed in the presence and absence of CH₃OH or CH₃OD. The addition of the protic solvents resulted in a significant decrease of molecular weight and a slight increase of internal alkene chain ends, suggesting that β-H elimination from alkylpalladium intermediates was accelerated, which led to the following alkene dissociation from the Pd center or alkene isomerization. In the presence of CH₃OD, linear polyethylenes possessing deuteriums in the main chain were obtained presumably via a β-H elimination, H/D exchange, and reinsertion sequence.