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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

DOI: doi:10.1021/om800558w

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
Research Division:Chemical Sciences
Research Group:Other Chemical Sciences
Research Field:Organometallic Chemistry
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Chemical Sciences
Author:Ariafard, A (Associate Professor Alireza Ariafard)
ID Code:91069
Year Published:2008
Web of Science® Times Cited:17
Deposited By:Chemistry
Deposited On:2014-05-07
Last Modified:2015-01-21
Downloads:0

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