Catalyst Speciation during ansa-Zirconocene-Catalyzed Polymerization of 1-Hexene Studied by UV-vis Spectroscopy-Formation and Partial Re-Activation of Zr-Allyl Intermediates | Sciact - CRIS-система Института катализа

Catalyst Speciation during ansa-Zirconocene-Catalyzed Polymerization of 1-Hexene Studied by UV-vis Spectroscopy-Formation and Partial Re-Activation of Zr-Allyl Intermediates Научная публикация

Журнал

Polymers
, E-ISSN: 2073-4360

Вых. Данные

Год: 2019, Том: 11, Номер: 6, Номер статьи : 936, Страниц : 20 DOI: 10.3390/polym11060936

Ключевые слова

Catalyst speciation; De-activation; Polymerization catalysis; Re-activation; UV-vis spectroscopy; Zirconocene-allyl cations

Авторы

Panchenko Valentina N. ^1,2 , Babushkin Dmitrii E. ¹ , Bercaw John E. ³ , Brintzinger Hans H. ⁴

Организации

1	Boreskov Institute of Catalysis, Russian Academy of Sciences, Siberian Branch, RU-630090 Novosibirsk, Russian
2	Novosibirsk State University, Pirogova Str. 2, 630090 Novosibirsk, Russian
3	Arnold and Mabel Beckman Laboratories of Chemical Synthesis, California Institute of Technology, Pasadena, CA 91125, USA
4	Fachbereich Chemie, Universität Konstanz, D-78464 Konstanz, Germany

Информация о финансировании (2)

1	Федеральное агентство научных организаций России	0303-2016-0009
2	German Research Foundation	Br 510/15-1

Catalyst speciation during polymerization of 1-hexene in benzene or toluene solutions of the catalyst precursor SBIZr(μ-Me)2AlMe2+ B(C6F5)4- (SBI = rac-dimethylsilyl-bis(1-indenyl)) at 23 °C is studied by following the accompanying UV-vis-spectral changes. These indicate that the onset of polymerization catalysis is associated with the concurrent formation of two distinct zirconocene species. One of these is proposed to consist of SBIZr-σ-polyhexenyl cations arising from SBIZr-Me+ (formed from SBIZr(μ-Me)2AlMe2+ by release of AlMe3) by repeated olefin insertions, while the other one is proposed to consist of SBIZr-η3-allyl cations of composition SBIZr-η3-(1-R-C3H4)+ (R = n-propyl), formed by σ-bond metathesis between SBIZr-Me+ and 1-hexene under release of methane. At later reaction stages, all zirconocene-σ-polymeryl cations appear to decay to yet another SBIZr-allyl species, i.e., to cations of the type SBIZr- η3-(x-R-(3-x)-pol-C3H3)+ (pol = i-polyhexenyl, x = 1 or 2). Renewed addition of excess 1-hexene is proposed to convert these sterically encumbered Zr-allyl cations back to catalytically active SBIZr-σ-polymeryl cations within a few seconds, presumably by initial 1-hexene insertion into the η1- isomer, followed by repeated additional insertions, while the initially formed, less crowded allyl cations, SBIZr-η3-(1-R-C3H4)+ appear to remain unchanged. Implications of these results with regard to the kinetics of zirconocene-catalyzed olefin polymerization are discussed. © 2019 by the authors.

Panchenko V.N. , Babushkin D.E. , Bercaw J.E. , Brintzinger H.H.
Catalyst Speciation during ansa-Zirconocene-Catalyzed Polymerization of 1-Hexene Studied by UV-vis Spectroscopy-Formation and Partial Re-Activation of Zr-Allyl Intermediates

Polymers. 2019. V.11. N6. 936 :1-20. DOI: 10.3390/polym11060936 WOS Scopus РИНЦ CAPlusCA PMID OpenAlex

Полный текст от издателя

Поступила в редакцию:	26 апр. 2019 г.
Принята к публикации:	24 мая 2019 г.
Опубликована online:	29 мая 2019 г.
Опубликована в печати:	1 июн. 2019 г.

Web of science:	WOS:000473819100008
Scopus:	2-s2.0-85067336842
РИНЦ:	41641868
Chemical Abstracts:	2019:1232441
Chemical Abstracts (print):	174:440073
PMID (PubMed):	31146475
OpenAlex:	W2946910387

БД	Цитирований
Scopus	5
Web of science	5
РИНЦ	4
OpenAlex	8