ИСТИНА

The concept of stiffening the backbone of olefin polymerization catalysts, particularly through conformational rigidity, has emerged as a powerful strategy to enhance catalytic performance. By restricting flexibility and influencing bond angles, it allows for tightening the active pocket, resulting in enhanced activity and stability, especially at elevated polymerization temperatures. This principle is exemplified in the development of ansa-metallocenes, where backbone rigidity has been a key focus, alongside substituent optimization. However, the strategy is equally applicable to post-metallocene catalysts, which often exhibit higher intrinsic flexibility. A vivid illustration of this strategy is demonstrated in the design of Salan-type catalysts, where stiffening the backbone was employed to effectively block isomerization of the polymerization-active fac-fac isomer of the catalyst into the inactive mer-mer form. This was achieved by preventing the rotation around the carbon-carbon bond between the methylene spacer and the phenyl ring via introduction of cyclic moieties functioning as “conformational locks”. As a result, the newly developed Indanosalan catalysts exhibited remarkable propene polymerization activity and molecular weight capability, outperforming the Salan-type catalysts known so far. This success highlights the broader potential of conformational rigidity as a design principle, offering a pathway to unlock the latent performance of underutilized catalyst systems.