Issue 3, 2006

Imidazolin-2-iminato titanium complexes: synthesis, structure and use in ethylenepolymerization catalysis

Abstract

The Staudinger reaction of the imidazolin-2-ylidenes, 1,3-di-tert-butylimidazolin-2-ylidene (1a), 1,3-diisopropylimidazolin-2-ylidene (1b), 1,3-diisopropyl-4,5-dimethylimidazolin-2-ylidene (1c), 1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (1d) and 1,3-bis(2,6-diisopropylphenylimidazolin-2-ylidene (1e), with trimethylsilyl azide furnishes the corresponding N-silylated 2-iminoimidazolines 2a–e, which react with [(η-C5H5)TiCl3] to afford half-sandwich cyclopentadienyl titanium complexes of the type [CpTi(L)Cl2] (3) (L = imidazolin-2-iminato ligand). Similarly, the reactions of 1,3-di-tert-butyl-2-(trimethylsilylimino)imidazoline (2a) with [(η-tBuC5H4)TiCl3] results in the formation of [(η-tBuC5H4)Ti(L)Cl2] (4) (L = 1,3-di-tert-butylimidazolin-2-imide). Bis(1,3-di-tert-butylimidazolin-2-iminato)titanium dichloride (5) is obtained from the reaction of two eq. of 2a with TiCl4. Treatment of 5 with methyllithium results in the formation of the corresponding dimethyl complex [L2Ti(CH3)2] (6), whereas [CpTi(L)(CH3)2] (7) is similarly obtained from 3a. The molecular structures of 3a, 3b, 3c, 3e·C7H8, 4 and 7 are reported revealing linearly coordinated imidazolin-2-iminato ligands together with very short Ti–N bond distances. All dichloro complexes (3a–e, 4 and 5) can be activated with methylaluminoxane (MAO) to give active catalysts for ethylene homopolymerization. In most cases, moderate to high activities are observed together with the formation of high (HMWPE) or even ultra high molecular weight polyethylene (UHMWPE).

Graphical abstract: Imidazolin-2-iminato titanium complexes: synthesis, structure and use in ethylene polymerization catalysis

Supplementary files

Article information

Article type
Paper
Submitted
17 Aug 2005
Accepted
28 Sep 2005
First published
28 Oct 2005

Dalton Trans., 2006, 459-467

Imidazolin-2-iminato titanium complexes: synthesis, structure and use in ethylene polymerization catalysis

M. Tamm, S. Randoll, E. Herdtweck, N. Kleigrewe, G. Kehr, G. Erker and B. Rieger, Dalton Trans., 2006, 459 DOI: 10.1039/B511752F

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements