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Synthesis of double-end-capped polyethylene by a cationic tris(pyrazolyl)borate zirconium benzyl complex
Citation
Nienkemper, K and Lee, H and Jordan, RF and Ariafard, A and Dang, L and Lin, Z, Synthesis of double-end-capped polyethylene by a cationic tris(pyrazolyl)borate zirconium benzyl complex, Organometallics, 27, (22) pp. 5867-5875. ISSN 0276-7333 (2008) [Refereed Article]
Copyright Statement
Copyright 2008 American Chemical Society
Abstract
The cationic complexes Tp*Zr(CH2Ph)2+ (I, B(C6F5)4− salt; Tp* = HB(3,5-Me2-pyrazolyl)3) and {(PhCH2)(H)B(μ-Me2pz)2}Zr(η2-Me2pz)(CH2Ph)+ (II; Me2pz = 3,5-Me2-pyrazolyl) polymerize ethylene at −78 to −60 °C to linear polyethylene (PE) without significant chain transfer. For I, chain growth takes place at only one benzyl group. Quenching these polymerizations with MeOH yields benzyl-capped PE (PhCH2(CH2CH2)nCH2CH3). Quenching I-catalyzed ethylene polymerization with Br2 yields double-end-capped PE containing benzyl and bromo chain ends (PhCH2(CH2CH2)nCH2CH2Br). DFT calculations on model catalysts show that ethylene insertion into a Zr−η2-CH2Ph bond requires greater structural distortion than insertion into a Zr−CH2CH2CH2Ph bond. The calculations also show that the β-H transfer to monomer and β-H elimination chain transfer pathways are both strongly disfavored for I, but the β-H transfer to monomer path may be possible for II.
Item Details
Item Type: | Refereed Article |
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Research Division: | Chemical Sciences |
Research Group: | Inorganic chemistry |
Research Field: | Organometallic chemistry |
Objective Division: | Expanding Knowledge |
Objective Group: | Expanding knowledge |
Objective Field: | Expanding knowledge in the chemical sciences |
UTAS Author: | Ariafard, A (Associate Professor Alireza Ariafard) |
ID Code: | 91069 |
Year Published: | 2008 |
Web of Science® Times Cited: | 21 |
Deposited By: | Chemistry |
Deposited On: | 2014-05-07 |
Last Modified: | 2015-01-21 |
Downloads: | 0 |
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