Connection of Stereoselectivity, Regioselectivity, and Molecular Weight Capability in rac-R′₂Si(2-Me-4-R-indenyl)₂ZrCl₂ Type Catalysts

A set of 19 silicon-bridged C2-symmetric zirconocenes rac-R′2Si(2-Me-4-R-indenyl)2ZrCl2 of varying steric demand in position 4 were synthesized and screened in propene homopolymerization in a high-throughput experimental setup. The size and accuracy of the experimental data set allow to identify surprisingly good correlations among stereoselectivity, regioselectivity, and molecular weight capability (R2 ≈ 0.8–0.9) over a broad range. We rationalize this trend by assuming that steric tuning in the 4-position affects both preferred insertion and stereoerror formation similarly but leaves other barriers largely unaffected. A quantitative structure–activity relationship based on one single computational descriptor, Δ%VBur—using the difference in the percent of buried volume between the “blocked” and “open” quadrants of the catalyst precursor—is established. Provided that a large sphere of 5.0 A is used, stereoselectivity can be predicted with unprecedented accuracy, i.e., a mean average deviation (MAD) of 0.1...