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Unprecedentedly High Activity and/or High Regio-/Stereoselectivity of Fluorenyl-Based CGC Allyl-Type η31-tert-Butyl(dimethylfluorenylsilyl)amido Ligated Rare Earth Metal Monoalkyl Complexes in Olefin Polymerization

1
Key Laboratory of Cluster Science of Ministry of Education, School of Chemistry and Chemical Engineering, Beijing Institute of Technology, 5 South Zhongguancun Street, Haidian District, Beijing 100081, China
2
Analytical and Testing Center, Liangxiang Campus of Beijing Institute of Technology, Liangxiang East Road, Fangshan District, Beijing 102488, China
3
NHC Key Laboratory of Food Safety Risk Assessment, China National Center for Food Safety Risk Assessment, Beijing 100021, China
*
Authors to whom correspondence should be addressed.
Polymers 2019, 11(5), 836; https://doi.org/10.3390/polym11050836
Received: 11 April 2019 / Revised: 29 April 2019 / Accepted: 30 April 2019 / Published: 8 May 2019
(This article belongs to the Collection Design and Synthesis of Polymers)
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Abstract

A series of fluorenyl-based constrained-geometry-configuration (CGC) allyl-type rare earth metal monoalkyl complexes bearing the divalent anionic η31-tert-butyl(dimethylfluorenylsilyl)amido (η31-FluSiMe2NtBu) ligand (η31-FluSiMe2NtBu)Ln(CH2SiMe3)(THF)2 (13) have been synthesized via the alkane elimination reaction between the FluHSiMe2NHtBu ligand and rare earth metal tri(trimethylsilylmethyl) complexes Ln(CH2SiMe3)3(THF)n. Their structures are characterized by means of NMR spectrum, elemental analyses, and X-ray diffraction. These complexes 13 are isostructural and isomorphous, and each of them adopts a distorted-trigonal-bipyramidal configuration containing one η31-FluSiMe2NtBu ligand, one CH2SiMe3 ligand, and two THF molecules. Unlike traditional CGC allyl-type rare earth metal complexes showing no or low activity and regio-/stereoselectivity in styrene or MMA polymerization, these complexes 13 exhibit high catalytic activities and/or high regio-/stereoselectivities in the cis-1,4-polymerization of isoprene and myrcene or in the syndiotactic polymerization of styrene under the aid of different activators (borate or borane) and AlR3. The in situ 1H NMR spectra suggest that the exchanges of chelating ligands such as alkyl groups and divalent anionic η31-FluSiMe2NtBu ligands between rare earth metal centers and Al centers result in the formation of a heterobimetallic tetraalkylaluminate complex R2Al(μ-R)2Ln(R)(μ-R)2AlR2, which is activated by activators to form a divalent cationic species [Ln(μ-R)2AlR2]2+ as a catalytically active species in the coordination–insertion polymerization of olefins. View Full-Text
Keywords: fluorenyl-based CGC allyl-type rare earth metal catalyst; η31-tert-butyl(dimethylfluorenylsilyl)amido ligand; coordination–insertion polymerization; olefins; regio-/stereoselectivity; active species fluorenyl-based CGC allyl-type rare earth metal catalyst; η31-tert-butyl(dimethylfluorenylsilyl)amido ligand; coordination–insertion polymerization; olefins; regio-/stereoselectivity; active species
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Guo, G.; Wu, X.; Yan, X.; Yan, L.; Li, X.; Zhang, S.; Qiu, N. Unprecedentedly High Activity and/or High Regio-/Stereoselectivity of Fluorenyl-Based CGC Allyl-Type η31-tert-Butyl(dimethylfluorenylsilyl)amido Ligated Rare Earth Metal Monoalkyl Complexes in Olefin Polymerization. Polymers 2019, 11, 836.

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