Catalytic Polymerization of Acetylenes and Olefins by Tetrakis(acetonitrile)palladium(II) Bis(tetrafluoroborate)

The cationic Pd(II) compound [Pd(CH₃C-N)₄](BF₄)₂ was found to catalyze the polymerization of H-C≡C-R (R = Ph, COOMe), styrene, α-methylstyrene, 1,3-cyclohexadiene, norbornylene, and norbornadiene under very mild conditions. The polyacetylenes are highly colored and have relatively high molecular weights. The poly(phenylacetylene) has a trans configuration around the C=C bond. The polymerization of 1,3-cyclohexadiene leads predominantly to the 1,2 polymer with only minimal cross-linking. The norbornane framework is retained during the polymerization of norbornylene. The poly(norbornadiene) is a highly crosslinked material.