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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.

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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.

Item Type:Journal Article, refereed
Communities & Collections:07 Faculty of Science > Department of Chemistry
DDC:540 Chemistry
Language:English
Date:3 April 2002
Deposited On:11 Feb 2008 12:25
Last Modified:27 Nov 2013 21:24
Publisher:American Chemical Society
ISSN:0002-7863
Publisher DOI:10.1021/ja010943b
Related URLs:http://pubs3.acs.org/acs/journals/doilookup?in_doi=10.1021/ja010943b
PubMed ID:11916416
Citations:Web of Science®. Times Cited: 47
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