Hafnocenes and MAO: Beware of Trimethylaluminum

A study has focused on finding intrinsic properties of Hafnocenes and methylalumoxane (MAO) based catalysts. The researchers have evaluated more carefully the behavior of HF-based homologues 3 and 4 with yield polymers with much higher average molecular masses rate, in propene polymerization with different activators. Analysts have used MAO or [Ph3C] [B(C 6F5)4]/Al(iso-butyl)3 (TrB/TIBA). TIBA was considered for its role as a scavenger and also as a convenient alkylating agent of metallocene dichlorides. The observation presented in the study highlighted a hidden layer of complexity underneath the seemingly straightforward picture of propene polymerization mediated by group 4 metallocene catalysts. Proposed structure demonstrated that catalyst behavior is strongly idiosyntcratic and that changing the transition metal from Zr(IV) to Hf(IV) in an otherwise identical ligand framework can change dramatically.