Effect of Metallocene Structures on their Performance in Ethene Polymerisation

Six (Cp)(4-phenyl-indenyl)MCl2 (A) and four (Cp)(1-phenyl-indenyl)MCl2 (C) (M=Zr/Hf) based complexes were tested in ethene homo- and copolymerisation under different conditions to explain how the differences in the complex structure affect the polymerisation process and the formed polymer. Polymerisation experiments reveal that hafnocene catalysts need a higher amount of MAO to reach the maximum activity than zirconocenes. Hafnocenes also incorporate better 1-hexene. Catalysts with the Cp* or 1,2,4-Me 3 Cp ligand show higher activity, and work well with [HNMe2Ph][B(C6F5)4]/TIBA as cocatalyst, but produce polymers with lower M n than the corresponding catalyst with a plain Cp ligand. The Cp* ligand seems to prevent 1-hexene incorporation. A methyl group in the 2-position of (Cp)(4-PhInd)ZrCl 2 decreases the activity and M n but favours 1-hexene insertion. Polymerisation activity is higher with catalysts with a 1-PhInd-ligand than with a 4-PhInd-ligand.