Synthesis of polyolefins containing silacycloalkane units in the main chain, 1 copolymerization of ethylene and disubstituted diallylsilanes involving intramolecular cyclization with zirconocene catalysts

Copolymerizations of ethylene and disubstituted diallylsilanes (CH ₂=CH-CH₂)₂R₂Si (R = CH₃, C₆H₅) have been investigated with various zirconocene catalysts using methylaluminoxane as a cocatalyst. The bridged stereospecific catalysts showed a higher reactivity for disubstituted diallylsilanes than the non-bridged aspecific catalysts, Disubstituted diallylsilanes were incorporated into the polymer chain via cyclization insertion preferentially, and formed 3,5-disubstituted silacyclohexane units in the polyethylene main chain. A zirconocene catalyst, dimethylsilylenebis(indenyl)zirconium dichloride, produced a copolymer containing pendant ullyl groups derived from the 1,2-insertion of diallyldiphenylsilane without cyclization.