The Interplay of Backbone Stiffening and Active Pocket Design in Bis(phenolate-ether) Zr/Hf Propene Polymerization Catalysts

For [OOOO]-type catalysts, the introduction of two methyl substituents behind the active site, at the backbone C3 linker, can substantially impact performance in propene polymerization catalysis depending also on the nature of the R1 substituent neighboring the active pocket. Catalyst molar mass capability and productivity can increase by 2-3 orders of magnitude; also, regioselectivity and stereoselectivity increase (2-3 fold). The results highlight (a) the importance of stiffening catalyst backbones of post-metallocene catalysts for high-temperature applications and (b) the complex interplay between backbone and active pocket design in post-metallocene olefin polymerization catalysis.