Fluxional Bis(phenoxy-imine) Zr and Ti Catalysts for Polymerization
Bis(phenoxy-imine) complexes of zirconium or titanium, a type of Fenokishi-Imin (FI) catalysts, allow the production of polyethylenes with well-defined bimodal molecular weight distributions. Interestingly, by substitution of phenyl rings in the bis(phenoxy-imine) ligands by perfluorinated phenyl ri...
| Autores: | , , , , , , |
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| Tipo de recurso: | artículo |
| Estado: | Versión aceptada para publicación |
| Fecha de publicación: | 2021 |
| País: | España |
| Institución: | Varias* (Consorci de Biblioteques Universitáries de Catalunya, Centre de Serveis Científics i Acadèmics de Catalunya) |
| Repositorio: | Recercat. Dipósit de la Recerca de Catalunya |
| OAI Identifier: | oai:recercat.cat:10256/19820 |
| Acceso en línea: | http://hdl.handle.net/10256/19820 |
| Access Level: | acceso abierto |
| Palabra clave: | Polimerització Catalitzadors Transferència de càrrega Teoria del funcional de densitat Polymerization Catalysts Charge transfer Density functionals |
| Sumario: | Bis(phenoxy-imine) complexes of zirconium or titanium, a type of Fenokishi-Imin (FI) catalysts, allow the production of polyethylenes with well-defined bimodal molecular weight distributions. Interestingly, by substitution of phenyl rings in the bis(phenoxy-imine) ligands by perfluorinated phenyl rings, the polymerization reaches a desired unimodal behaviour. These catalysts have 3 isomers of similar energy that can be easily interconverted. It is likely that the bimodal behaviour is due to the coexistence of more than one isomer in the reaction vessel. Here, we perform static and dynamic DFT calculations to understand the isomerization of the catalytic active species. We analyze the relative Gibbs energies of the different isomers and the barriers for the isomerization processes. Further characterization of the isomers is obtained through stereo maps, aromaticity measures, and NCI plots. Our results show that by changing the phenyl group by a perfluorinated phenyl ring, one of the isomers is particularly stabilized, thus explaining the unimodal behaviour of the polyethylene production process |
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