Header

UZH-Logo

Maintenance Infos

Formation of cyclodimeric (sp(2)-C(1))-bridged Cp/-oxido ("CpC(1)O"M(IV)X(2)) group 4 metal Ziegler-Natta catalyst systems--how important is the "constrained geometry" effect?


Kunz, K; Erker, G; Kehr, G; Fröhlich, R; Jacobsen, H; Berke, Heinz; Blacque, Olivier (2002). Formation of cyclodimeric (sp(2)-C(1))-bridged Cp/-oxido ("CpC(1)O"M(IV)X(2)) group 4 metal Ziegler-Natta catalyst systems--how important is the "constrained geometry" effect? Journal of the American Chemical Society, 124(13):3316-3326.

Abstract

Deprotonation of sodium acetylcyclopentadienide (11) was achieved by treatment with LDA in THF to generate the dianion equivalent [Cp-C(=CH(2))-O](2-)(12). Transmetalation with Cl(2)Ti(NMe(2))(2) gave ([Cp-C(=CH(2))-O]Ti(NMe(2))(2))(2) (17); treatment of 12 with Cl(2)Zr(NEt(2))(2)(THF)(2) furnished (([Cp-C(=CH(2))-O]Zr(NEt(2))(2))(2) (18). Cryoscopy in benzene revealed a dimeric structure of 18 in solution. Complex 18 was characterized further by an X-ray crystal structure analysis and by DFT calculations. The two zirconium centers of 18 are connected by means of two symmetry-equivalent eta(5):kappaO[Cp-C(=CH(2))-O] ligands. The ligand backbone shows no specific steric constraints, different from the formally related "constrained geometry" systems such as [Cp-SiMe(2)-NCMe(3)]Zr(NMe(2))(2) (1b). Nevertheless, upon treatment with MAO the CpCO group 4 metal complex system (18) generates an active homogeneous Ziegler-Natta catalyst for effective ethene/1-octene copolymerization, with up to 20% 1-octene having become incorporated in the resulting copolymer at 90 degrees C.

Abstract

Deprotonation of sodium acetylcyclopentadienide (11) was achieved by treatment with LDA in THF to generate the dianion equivalent [Cp-C(=CH(2))-O](2-)(12). Transmetalation with Cl(2)Ti(NMe(2))(2) gave ([Cp-C(=CH(2))-O]Ti(NMe(2))(2))(2) (17); treatment of 12 with Cl(2)Zr(NEt(2))(2)(THF)(2) furnished (([Cp-C(=CH(2))-O]Zr(NEt(2))(2))(2) (18). Cryoscopy in benzene revealed a dimeric structure of 18 in solution. Complex 18 was characterized further by an X-ray crystal structure analysis and by DFT calculations. The two zirconium centers of 18 are connected by means of two symmetry-equivalent eta(5):kappaO[Cp-C(=CH(2))-O] ligands. The ligand backbone shows no specific steric constraints, different from the formally related "constrained geometry" systems such as [Cp-SiMe(2)-NCMe(3)]Zr(NMe(2))(2) (1b). Nevertheless, upon treatment with MAO the CpCO group 4 metal complex system (18) generates an active homogeneous Ziegler-Natta catalyst for effective ethene/1-octene copolymerization, with up to 20% 1-octene having become incorporated in the resulting copolymer at 90 degrees C.

Statistics

Citations

49 citations in Web of Science®
49 citations in Scopus®
Google Scholar™

Altmetrics

Additional indexing

Item Type:Journal Article, refereed
Communities & Collections:07 Faculty of Science > Department of Chemistry
Dewey Decimal Classification:540 Chemistry
Language:English
Date:3 April 2002
Deposited On:11 Feb 2008 12:25
Last Modified:05 Apr 2016 12:20
Publisher:American Chemical Society
ISSN:0002-7863
Publisher DOI:https://doi.org/10.1021/ja010943b
Related URLs:http://pubs3.acs.org/acs/journals/doilookup?in_doi=10.1021/ja010943b
PubMed ID:11916416

Download

Full text not available from this repository.
View at publisher

TrendTerms

TrendTerms displays relevant terms of the abstract of this publication and related documents on a map. The terms and their relations were extracted from ZORA using word statistics. Their timelines are taken from ZORA as well. The bubble size of a term is proportional to the number of documents where the term occurs. Red, orange, yellow and green colors are used for terms that occur in the current document; red indicates high interlinkedness of a term with other terms, orange, yellow and green decreasing interlinkedness. Blue is used for terms that have a relation with the terms in this document, but occur in other documents.
You can navigate and zoom the map. Mouse-hovering a term displays its timeline, clicking it yields the associated documents.

Author Collaborations