Improving the Behavior of Bis(phenoxyamine) Group 4 Metal Catalysts for Controlled Alkene Polymerization

A study was conducted to improve the behavior of bis(phenoxyamine) group 4 metal catalysts for controlled alkene polymerization. The performance of bis(phenoxyamine)Hf homologues was investigated, assuming that a higher chain propagation to transfer ratio was associated with a longer duration of the controlled regime. The bis(phenoxyamine)Hf-dibenzyl complexes Hf-1 and Hf-2 were prepared similarly to the Zr-1 and Zr-2 Hf homologues. The complexes were activated with methylalumoxane (MAO) in combination with 2,6-di-tert-bytylphenol (TBP) to scavenge free trimethylaluminum and inhibit chain transfer through trans-alkylation. The complexes were also tested comparatively with Zr-1 and Zr-2 in ethene and propene polymerization at 25 °C in toluene solution.