Polymerization of Phenylacetylene Catalyzed by Diphosphinopalladium(II) Complexes

Cationic bis(phosphino)palladium complexes were generated in situ from the reaction of (dppf)PdCl(CH3), (dippf)PdCl(CH3), (dppe)PdCl(CH3), (dppf)PdCl2, (dippf)PdCl2, and (dppe)PdCl2 (dppf = bis(diphenylphosphino)ferrocene, dippf = bis(diisopropylphosphino)ferrocene, and dppe = bis(diphenylphosphino)ethane) with AgOTf. The dppf− and dippf−paladium complexes catalyzed the polymerization of phenylacetylene (PA) whereas the dppe analogues formed phenylacetylene oligomers. Solvent and temperature effects on polymerization were investigated and showed that best test polydispersity for phenylacetylene (PPA) formation was a 1:1 CH2Cl2−CH3CN solvent mixture and room temperature.