Ziegler-Natta catalyst (atactic)

Other names: zirconocene dichloride, dichloridobis(η⁵-cyclopentadienyl)zirconium

C₁₀H₁₀Cl₂Zr

14/50 common

Zirconocene dichloride here functions as a Ziegler-Natta catalyst for olefin polymerization, in this case for the production of so-called "atactic" polyolefins with no stereochemical control. Its structure is a bent metallocene with a zirconium center coordinated to two pentahaptic cyclopentadienyl (Cp) ligands and two chloride ligands. Unlike stereoselective Ziegler-Natta catalysts, this variant produces polymers with a random configuration, leading to amorphous materials with lower crystallinity. In practical use, zirconocene dichloride must first be activated with methylaluminoxane (MAO) or similar co-catalysts to initiate polymerization.