Wydział Chemii

Mateusz Janeta

Julius X. Heidlas

Olafs Daugulis

Maurice Brookhart

2021

Angewandte Chemie - International Edition

60

4566-4569

10.1002/anie.202013854

Naukowa

Angielski

Artykuł

The reactivity of Ni^II and Pd^II olefin polymerization catalysts can be enhanced by introduction of electron‐withdrawing substituents on the supporting ligands rendering the metal centers more electrophilic. Reported here is a comparison of ethylene polymerization activity of a classical salicyliminato nickel catalyst substituted with the powerful electron‐withdrawing 2,4,6‐triphenylpyridinium (trippy) group to the ‐CF₃ analogue. The trippy substituent is substantially more electron‐withdrawing (σ_meta=0.63) than the trifluoromethyl group (σ_meta=0.43) which results in a ca. 8‐fold increase in catalytic turnover frequency. An additional advantage of trippy is the high steric bulk relative to the trifluoromethyl group. This feature results in a four‐fold increase in polymer molecular weight owing to enhanced retardation of chain transfer. A significant increase in catalyst lifetime is observed as well.

homogeneous catalysis, ligand design, nickel, polyolefins

http://dx.doi.org/10.1002/anie.202013854

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