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Connection of Stereoselectivity, Regioselectivity, and Molecular Weight Capability in rac-R'2Si(2-Me-4-R-indenyl)2ZrCl2 Type Catalystsстатья Электронная публикация
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 24 ноября 2018 г.
- Авторы: Ehm Christian, Vittoria Antonio, Goryunov Georgy P., Kulyabin Pavel S., Budzelaar Peter H.M., Voskoboynikov Alexander Z., Busico Vincenzo, Uborsky Dmitry V., Cipullo Roberta
- Журнал: Macromolecules
- Том: 51
- Номер: 20
- Год издания: 2018
- Издательство: American Chemical Society
- Местоположение издательства: United States
- Первая страница: 8073
- Последняя страница: 8083
- DOI: 10.1021/acs.macromol.8b01546
- Аннотация: 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 Å is used, stereoselectivity can be predicted with unprecedented accuracy, i.e., a mean average deviation (MAD) of 0.18 kcal/mol (ΔΔG‡enantio), 0.0007 (σ, probability that the preferred propene enantioface is selected at an active site of given chirality), or 0.3% (mmmm pentads). On the basis of this empirical model, we predicted that the catalyst with R = o-tolyl is an ideal candidate for high stereoselectivity/high MW capability. Ad hoc synthesis and testing of the precursor confirmed the expectations: the catalyst shows the highest stereoselectivity reported so far (σ = 0.9999) for metallocenes at 60 °C, while maintaining a high MW capability (Mw > 1 MDa) and relatively high regioselectivity.
- Добавил в систему: Воскобойников Александр Зельманович