Abstract
The meso- and rac-like isomers of bis{η 5-(1-benzyl)indenyl}zirconium dichloride ( 5), bis{η 5-(1- para-methoxybenzyl)indenyl}zirconium dichloride ( 6), bis{η 5-(1- para-fluoro-benzyl)indenyl}zirconium dichloride ( 7) and bis{η 5-(1-phenylethyl)indenyl}zirconium dichloride ( 8) were synthesized and isolated. Solid-state structures of meso- and rac-like 5 were determined by X-ray structure analysis. Polymerization properties of the methylaluminoxane (MAO) activated diastereomers of complexes 5– 8 were studied in ethene polymerizations under different monomer concentrations. The rac-like isomer of 1-phenylethyl-substituted 8/MAO showed significantly higher activity than the 1-benzyl substituted analogs 5– 7/MAO. In addition, rac- 8/MAO behaves like a single center catalyst producing polyethene with narrow molar mass distribution (1.8–1.9), while diastereomers of 5– 7/MAO produce polymers with molar mass distributions varying from 2.7 up to 10.3. The rac and meso-like isomers of 5– 7/MAO have different response on the monomer concentration. Quantum chemical calculations suggest a strong interaction between the benzyl substituent and the electron deficient zirconium center. The phenyl metal coordination energies depend on the electronic properties of the para-substituent. In 8/MAO, due to the ethyl spacer, the coordination does not have a significant role and therefore much higher activity and single center polymerization behavior is observed.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
