Bis(1,3-di-tert-butylimidazolin-2-iminato) titanium complexes as effective catalysts for the monodisperse polymerization of propylene

Manab Sharma; Haneen Simaan Yameen; Boris Tumanskii; Sabina Alexandra Filimon; Matthias Tamm; Moris S. Eisen

doi:10.1021/ja3071545

Bis(1,3-di-tert-butylimidazolin-2-iminato) titanium complexes as effective catalysts for the monodisperse polymerization of propylene

Manab Sharma, Haneen Simaan Yameen, Boris Tumanskii, Sabina Alexandra Filimon, Matthias Tamm^*, Moris S. Eisen

^*Corresponding author for this work

Research output: Contribution to journal › Article › peer-review

53 Scopus citations

Abstract

The use of bis(1,3-di-tert-butylimidazolin-2-iminato) titanium dichloride (1) and dimethyl (2) complexes in the polymerization of propylene is presented. The complexes were activated using different amounts of methylalumoxane (MAO), giving in each case a very active catalytic mixture and producing polymers with a narrow molecular weight distribution (polydispersity = 1.10). The use of the cocatalyst triphenylcarbenium (trityl) tetra(pentafluorophenyl)borate totally inhibits the reaction, producing the corresponding bis(1,3-di-tert- butylimidazolin-2-iminato) titanium(III) methyl complex, the trityl radical (CPh₃), the anionic MeB(C₆F₅)₄ ^-, B(C₆F₅)₃, and the bis(1,3-di-tert-butylimidazolin-2-iminato) titanium(IV) dimethyl·B(C ₆F₅)₃ complex. The use of a combination of physical methods such as NMR, ESR-C₆₀, and MALDI-TOF analyses enabled us to propose a plausible mechanism for the polymerization of propylene, presenting that the polymerization is mainly carried out in a living fashion. In addition, we present a slow equilibrium toward a small amount of a dormant species responsible for 2,1-misinsertions and chain transfer processes.

Original language	English
Pages (from-to)	17234-17244
Number of pages	11
Journal	Journal of the American Chemical Society
Volume	134
Issue number	41
DOIs	https://doi.org/10.1021/ja3071545
State	Published - 17 Oct 2012
Externally published	Yes

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title = "Bis(1,3-di-tert-butylimidazolin-2-iminato) titanium complexes as effective catalysts for the monodisperse polymerization of propylene",

abstract = "The use of bis(1,3-di-tert-butylimidazolin-2-iminato) titanium dichloride (1) and dimethyl (2) complexes in the polymerization of propylene is presented. The complexes were activated using different amounts of methylalumoxane (MAO), giving in each case a very active catalytic mixture and producing polymers with a narrow molecular weight distribution (polydispersity = 1.10). The use of the cocatalyst triphenylcarbenium (trityl) tetra(pentafluorophenyl)borate totally inhibits the reaction, producing the corresponding bis(1,3-di-tert- butylimidazolin-2-iminato) titanium(III) methyl complex, the trityl radical (CPh3), the anionic MeB(C6F5)4 -, B(C6F5)3, and the bis(1,3-di-tert-butylimidazolin-2-iminato) titanium(IV) dimethyl·B(C 6F5)3 complex. The use of a combination of physical methods such as NMR, ESR-C60, and MALDI-TOF analyses enabled us to propose a plausible mechanism for the polymerization of propylene, presenting that the polymerization is mainly carried out in a living fashion. In addition, we present a slow equilibrium toward a small amount of a dormant species responsible for 2,1-misinsertions and chain transfer processes.",

author = "Manab Sharma and Yameen, {Haneen Simaan} and Boris Tumanskii and Filimon, {Sabina Alexandra} and Matthias Tamm and Eisen, {Moris S.}",

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AU - Sharma, Manab

AU - Yameen, Haneen Simaan

AU - Tumanskii, Boris

AU - Filimon, Sabina Alexandra

AU - Tamm, Matthias

AU - Eisen, Moris S.

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N2 - The use of bis(1,3-di-tert-butylimidazolin-2-iminato) titanium dichloride (1) and dimethyl (2) complexes in the polymerization of propylene is presented. The complexes were activated using different amounts of methylalumoxane (MAO), giving in each case a very active catalytic mixture and producing polymers with a narrow molecular weight distribution (polydispersity = 1.10). The use of the cocatalyst triphenylcarbenium (trityl) tetra(pentafluorophenyl)borate totally inhibits the reaction, producing the corresponding bis(1,3-di-tert- butylimidazolin-2-iminato) titanium(III) methyl complex, the trityl radical (CPh3), the anionic MeB(C6F5)4 -, B(C6F5)3, and the bis(1,3-di-tert-butylimidazolin-2-iminato) titanium(IV) dimethyl·B(C 6F5)3 complex. The use of a combination of physical methods such as NMR, ESR-C60, and MALDI-TOF analyses enabled us to propose a plausible mechanism for the polymerization of propylene, presenting that the polymerization is mainly carried out in a living fashion. In addition, we present a slow equilibrium toward a small amount of a dormant species responsible for 2,1-misinsertions and chain transfer processes.

AB - The use of bis(1,3-di-tert-butylimidazolin-2-iminato) titanium dichloride (1) and dimethyl (2) complexes in the polymerization of propylene is presented. The complexes were activated using different amounts of methylalumoxane (MAO), giving in each case a very active catalytic mixture and producing polymers with a narrow molecular weight distribution (polydispersity = 1.10). The use of the cocatalyst triphenylcarbenium (trityl) tetra(pentafluorophenyl)borate totally inhibits the reaction, producing the corresponding bis(1,3-di-tert- butylimidazolin-2-iminato) titanium(III) methyl complex, the trityl radical (CPh3), the anionic MeB(C6F5)4 -, B(C6F5)3, and the bis(1,3-di-tert-butylimidazolin-2-iminato) titanium(IV) dimethyl·B(C 6F5)3 complex. The use of a combination of physical methods such as NMR, ESR-C60, and MALDI-TOF analyses enabled us to propose a plausible mechanism for the polymerization of propylene, presenting that the polymerization is mainly carried out in a living fashion. In addition, we present a slow equilibrium toward a small amount of a dormant species responsible for 2,1-misinsertions and chain transfer processes.

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Bis(1,3-di-tert-butylimidazolin-2-iminato) titanium complexes as effective catalysts for the monodisperse polymerization of propylene

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