Significant Polar Comonomer Enchainment in Zirconium‐Catalyzed,Masking Reagent‐Free,Ethylene Copolymerizations

In principal, the direct copolymerization of ethylene with polar comonomers should be the most efficient means to introduce functional groups into conventional polyolefins but remains a formidable challenge. Despite the tremendous advances in group 4‐centered catalysis for olefin polymerization, successful examples of ethylene + polar monomer copolymerization are rare, especially without Lewis acidic masking reagents. Here we report that certain group 4 catalysts are very effective for ethylene + CH₂=CH(CH₂)_nNR₂ copolymerizations with activities up to 3400 Kg copolymer mol^?1‐Zr h^‐1 atm^‐1, and with comonomer enchainment up to 5.5 mol % in the absence of masking reagents. Group 4 catalyst‐amino‐olefin structure–activity‐selectivity relationships reflect the preference of olefin activation over free amine coordination, which is supported by mechanistic experiments and DFT analysis. These results illuminate poorly understood facets of d⁰ metal‐catalyzed polar olefin monomer copolymerization processes.