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Exploring the Nature of the Energy Barriers on the Mechanism of the Zirconocene-Catalyzed Ethylene Polymerization: A Quantitative Study from Reaction Force Analysis

Ortega, Daniela E. and Matute, Ricardo A. and Toro-Labbé, Alejandro (2020) Exploring the Nature of the Energy Barriers on the Mechanism of the Zirconocene-Catalyzed Ethylene Polymerization: A Quantitative Study from Reaction Force Analysis. Journal of Physical Chemistry C, 124 (15). pp. 8198-8209. ISSN 1932-7447. https://resolver.caltech.edu/CaltechAUTHORS:20200331-094810316

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Abstract

Ethylene polymerization mediated by methyl-bis(cyclopentadienyl)-zirconium or zirconocene catalyst, [ZrCp₂CH₃]⁺, is one of the most popular catalytic reaction for polyethylene production. Rationalizing the major effects that control the polymer growth result in a challenge for computational studies. Through quantum chemical calculations, we characterized the zirconocene ethylene polymerization reaction mechanism: chain initiation (I; first ethylene insertion) [ZrCp₂CH₂CH₂CH₃]⁺, chain propagation (P; from second (P₁) to ninth (P₉) ethylene insertion) [ZrCp₂ (CH₂)₂₀CH₃]⁺, and chain termination processes (T; β-hydrogen elimination from P₅ or P₉) [ZrHCp₂ (H₂C═CH(CH₂)₁₈CH₃]⁺ are analyzed through the potential energy surface (PES) and reaction force analysis (RFA). The RFA approach involves pulling out the portion of an activation barrier that corresponds to distorting reactants into the geometries they adopt in a transition state structure until it reaches the structural relaxation toward the equilibrium geometry of the product. Because the interactions between the zirconocene and the ethylene molecule are influenced by a combination of several kinds of steric and electronic effects, it is indispensable to understanding these interactions in order to rationalize and predict in a quantitative manner the reaction barrier heights and the concomitant polymer growth. In the present work, we employ a simple procedure within the framework of the RFA and the density functional steric energy decomposition analysis (EDA) approach to quantitatively separate the different types of interactions; steric (ΔE_s), electrostatic (ΔE_e), and quantum (ΔE_q) effects in order to predict the impact of each factor on the course of the polymerization process as well as for the polymer control and design.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/acs.jpcc.9b11615DOIArticle
ORCID:
AuthorORCID
Ortega, Daniela E.0000-0002-0724-4206
Matute, Ricardo A.0000-0002-0644-3799
Additional Information:© 2020 American Chemical Society. Received: December 17, 2019; Revised: March 30, 2020; Published: March 30, 2020. D.E.O. acknowledges the financial support from the Postdoctoral FONDECYT Grant No. 3190252. R.A.M and A.T.-L. acknowledge FONDECYT Grants No. 1181260 and No. 1181072. Author Contributions: D.E.O. wrote the manuscript and performed all the calculations. Both R.A.M. and A.T.-L. contributed to the final version of the manuscript. A.T.-L. helped supervise the project. The authors declare no competing financial interest.
Funders:
Funding AgencyGrant Number
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)3190252
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1181260
Fondo Nacional de Desarrollo Científico y Tecnológico (FONDECYT)1181072
Issue or Number:15
Record Number:CaltechAUTHORS:20200331-094810316
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20200331-094810316
Official Citation:Exploring the Nature of the Energy Barriers on the Mechanism of the Zirconocene-Catalyzed Ethylene Polymerization: A Quantitative Study from Reaction Force Analysis. Daniela E. Ortega, Ricardo A. Matute, and Alejandro Toro-Labbé. The Journal of Physical Chemistry C 2020 124 (15), 8198-8209; DOI: 10.1021/acs.jpcc.9b11615
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:102194
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:31 Mar 2020 17:01
Last Modified:16 Apr 2020 17:33

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