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Talzi, E. P.; Babushkin, Dmitrii E.; Semikolenova, Nina V.; Зудин, В. Н.; Захаров, В. А.

doi:10.1023/a:1010451213400

Cited by 26 publications

(11 citation statements)

References 7 publications

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“…The mechanism by which polymerization is believed to proceed is essentially the same as for early transition metals, that is, the active species is a cationic metal( II ) alkyl complex. One recent publication contradicts this belief for the iron‐based catalyst system 2. Mechanistic studies are difficult for several reasons.…”

Section: Methodsmentioning

confidence: 99%

Olefin Polymerization with [{bis(imino)pyridyl}CoIICl2]: Generation of the Active Species Involves CoI

et al. 2001

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The independent discovery by the groups of Brookhart and Gibson that bis(imino)pyridyl (N 3 ) complexes of iron and cobalt ( Figure 1) are precursors for active polymerization and oligomerization catalysts [1] has put a new perspective on late transition metals as polymerization catalysts. However, there have been very few reports of successful extension of the system (other than trivial changes of substituents), which indicates that our understanding of this catalytic system is still incomplete.The mechanism by which polymerization is believed to proceed is essentially the same as for early transition metals, that is, the active species is a cationic metal(ii) alkyl complex. One recent publication contradicts this belief for the ironbased catalyst system. [2] Mechanistic studies are difficult for several reasons. In addition to problems of high activity (and hence low concentration) and the large excess of MAO (MAO methylaluminoxane) used, the Fe and Co systems are also paramagnetic, which complicates NMR spectroscopy studies. Gibson has mentioned some preliminary studies of iron ± alkyl species which appear to support formation of [N 3 FeR] [3] moieties, but so far no reports on the corresponding Co systems have appeared. The groups of Gambarotta [4a] Figure 4. The relationship between the electron transfer and the metal ± ligand bond lengths. crossover phenomenon. However, the present calorimetric study clearly revealed that this novel phenomenon is quite different from usual (or classical) spin-crossover phenomenon. Experimental SectionSynthesis of 1 is reported elsewhere. [1, 4] Heat capacity measurements between 8 K and 300 K were made with a home-built adiabatic microcalorimeter. [11, 12] The mass of the sample for calorimetry was 0.95853 g (1.4556 mmol). A small amount of He gas was sealed in the calorimeter cell to aid the heat transfer.

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Section: Methodsmentioning

confidence: 99%

Olefin Polymerization with [{bis(imino)pyridyl}CoIICl2]: Generation of the Active Species Involves CoI

et al. 2001

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“…Organoaluminum co‐catalysts (AlMe 3 , AlMe 2 Cl, MAO) and [Ph 3 C][B(C 6 F 5 ) 4 ] were purchased from Aldrich. Al(CD 3 ) 3 was synthesized by Dr. D. Babushkin according to the published procedure . Ethylene polymerization was performed in a 0.3 L steel reactor.…”

Section: Methodsmentioning

confidence: 99%

Vanadium(III)‐Catalyzed Polymerization of α‐Olefins: Detailed NMR Spectroscopic Characterization of Intermediates Modeling the Active Species of Polymerization

et al. 2017

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The ion pairs formed upon the activation of bis(imino)pyridine complex LVCl3 (L=2,6‐bis[1‐(2,6‐dimethylphenylimino)ethyl]pyridine) with AlMe2Cl and AlMe3/[Ph3C][B(C6F5)4] were characterized in detail by 1H and 2H NMR spectroscopy, including the first NMR observation of the VIII−CH3 group. The following ion pairs were identified: [L(Cl)VIII(μ‐Cl)2AlMe2]+[A]−, [L(Me)VIII(μ‐Cl)2AlMe2]+[A]−, [LVIIICl2(THF)]+[A]−, and [LVIII(Cl)Me(THF)]+[A]− ([A]−=[AlMe3Cl]− or [B(C6F5)4]−, THF=tetrahydrofuran). The nature of the ethylene polymerization active species is discussed.

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“…For a standard bis(iminopyridyl)Co(II) dichloride catalyst, Gal and coworkers reported on the formation of a cobalt(I), instead of a cobalt(II), species that is active in ethylene polymerization [126]. This is in absolute contradiction to the cationic metal(II) alkyl species that have been considered so far as active species, or to previously postulated neutral Fe(0) compounds [127]. Further investigations on this issue will certainly have implications on the design of new polymerization catalysts.…”

Section: Fe- Co- Pd- and Ni-based Systemsmentioning

confidence: 95%

Transition metal-based polymer chemistry: a critical micro-review

Buchmeiser¹

2002

Designed Monomers and Polymers

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Abstract-This micro-review summarizes mainly recent (i.e. mostly later than 1995) and important developments in transition metal-catalyzed polymerization and their impact on polymer synthesis. It is not intended to be entirely comprehensive, yet will focus on signi cant improvements or interesting aspects in certain areas of polymer chemistry. For this particular reason, not all transition metal-based polymerizations will be fully covered. Instead, besides providing a 'snapshot' of the state of the art, it was a major intention to outline the main advantages and disadvantages of certain important polymerizations in a critical, yet hopefully objective way.

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Untitled

Cited by 26 publications

References 7 publications

Olefin Polymerization with [{bis(imino)pyridyl}CoIICl2]: Generation of the Active Species Involves CoI

Olefin Polymerization with [{bis(imino)pyridyl}CoIICl2]: Generation of the Active Species Involves CoI

Vanadium(III)‐Catalyzed Polymerization of α‐Olefins: Detailed NMR Spectroscopic Characterization of Intermediates Modeling the Active Species of Polymerization

Transition metal-based polymer chemistry: a critical micro-review

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