Formation and Nature of the Active Sites in Bis(imino)pyridine Iron-Based Polymerization Catalysts Full article
| Journal |
Organometallics
ISSN: 0276-7333 , E-ISSN: 1520-6041 |
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| Output data | Year: 2009, Volume: 28, Number: 11, Pages: 3225-3232 Pages count : 8 DOI: 10.1021/om8010905 | ||
| Tags | Alumina Catalysi sCatalysts Chemical activation Electron resonance Electron spin resonance spectroscopy Ethylene Paramagnetic resonance Polymerization Polymers Pyridine Quantum theory Spin dynamics | ||
| Authors |
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| Affiliations |
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Funding (1)
| 1 | Russian Foundation for Basic Research | 09-03-00485 |
Abstract:
The activation of 2,6-bis(2,6-diisopropylphenylimino)ethylpyridine iron-based catalysts of ethylene polymerization with methylalumoxane (MAO) and aluminum trialkyls has been studied in detail by 1H NMR and EPR spectroscopy. Neutral catalytically active species are formed in LiPrFeCl2/Al(Alk)3 systems. They are complexes [LiPr(−)Fe(+)(μ-Me)2AlMe2] (6) or [LiPr(−)Fe(+)(μ-iBu)(μ-X)Al(iBu)2] (7 or 8, X = iBu or Cl), depending on the activator used (either AlMe3 or Al(iBu)3). On the contrary, when “AlMe3-free” methylalumoxane (PMAO) is used as the activator, catalytically active ion pairs of the type [LFeII(μ-Me)2AlMe2]+[MeMAO]− (3) are formed. Intermediates 6 and 8 are relatively unstable and decay within minutes at room temperature, giving rise to an EPR-active iron species with a signal at g = 2.08, presumably of the type L′FeI−Alk (L′FeI(μ-Alk)2Al(Alk)2) in the low-spin state S = 1/2 (where L′ is a modified bis(imino)pyridine ligand). Polymer properties for the different catalyst/activator systems are presented.
Cite:
Brylyakov K.P.
, Talzi E.P.
, Semikolenova N.V.
, Zakharov V.A.
Formation and Nature of the Active Sites in Bis(imino)pyridine Iron-Based Polymerization Catalysts
Organometallics. 2009. V.28. N11. P.3225-3232. DOI: 10.1021/om8010905 WOS Scopus РИНЦ ANCAN OpenAlex
Formation and Nature of the Active Sites in Bis(imino)pyridine Iron-Based Polymerization Catalysts
Organometallics. 2009. V.28. N11. P.3225-3232. DOI: 10.1021/om8010905 WOS Scopus РИНЦ ANCAN OpenAlex
Dates:
| Submitted: | Nov 16, 2008 |
| Published online: | May 1, 2009 |
| Published print: | Jun 8, 2009 |
Identifiers:
| Web of science: | WOS:000266605100014 |
| Scopus: | 2-s2.0-66349133054 |
| Elibrary: | 13613616 |
| Chemical Abstracts: | 2009:525975 |
| Chemical Abstracts (print): | 151:8599 |
| OpenAlex: | W1968569128 |