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Efficient Copolymerization of Acrylate and Ethylene with Neutral P, O-Chelated Nickel Catalysts: Mechanistic Investigations of Monomer Insertion and Chelate Formation

Xiong, Shuoyan and Shoshani, Manar M. and Zhang, Xinglong and Spinney, Heather A. and Nett, Alex J. and Henderson, Briana S. and Miller, Thomas F., III and Agapie, Theodor (2021) Efficient Copolymerization of Acrylate and Ethylene with Neutral P, O-Chelated Nickel Catalysts: Mechanistic Investigations of Monomer Insertion and Chelate Formation. Journal of the American Chemical Society, 143 (17). pp. 6516-6527. ISSN 0002-7863. doi:10.1021/jacs.1c00566. https://resolver.caltech.edu/CaltechAUTHORS:20210430-120931834

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Abstract

The efficient copolymerization of acrylates with ethylene using Ni catalysts remains a challenge. Herein, we report two neutral Ni(II) catalysts (POP-Ni-py (1) and PONap-Ni-py (2)) that exhibit high thermal stability and significantly higher incorporation of polar monomer (for 1) or improved resistance to tert-butylacrylate (tBA)-induced chain transfer (for 2), in comparison to previously reported catalysts. Nickel alkyl complexes generated after tBA insertion, POP-Ni-CCO(py) (3) and PONap-Ni-CCO(py) (4), were isolated and, for the first time, characterized by crystallography. Weakened lutidine vs pyridine coordination in 2-lut facilitated the isolation of a N-donor-free adduct after acrylate insertion PONap-Ni-CCO (5) which represents a novel example of a four-membered chelate relevant to acrylate polymerization catalysis. Experimental kinetic studies of six cases of monomer insertion with aforementioned nickel complexes indicate that pyridine dissociation and monomer coordination are fast relative to monomer migratory insertion and that monomer enchainment after tBA insertion is the rate limiting step of copolymerization. Further evaluation of monomer insertion using density functional theory studies identified a cis–trans isomerization via Berry-pseudorotation involving one of the pendant ether groups as the rate-limiting step for propagation, in the absence of a polar group at the chain end. The energy profiles for ethylene and tBA enchainments are in qualitative agreement with experimental measurements.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1021/jacs.1c00566DOIArticle
ORCID:
AuthorORCID
Shoshani, Manar M.0000-0002-4051-3367
Zhang, Xinglong0000-0003-1698-692X
Miller, Thomas F., III0000-0002-1882-5380
Agapie, Theodor0000-0002-9692-7614
Additional Information:© 2021 American Chemical Society. Received: January 20, 2021; Published: April 22, 2021. We are grateful to Dow (TA) and the Natural Sciences and Engineering Research Counsel of Canada (MMS) for funding. We thank Brad Bailey and Jerzy Klosin (Dow) for insightful discussions. X.Z. acknowledges the Agency for Science, Technology and Research (A*STAR), Singapore, for a National Science Scholarship. We thank Michael Takase and Lawrence Henling for assistance with X-ray crystallography and David VanderVelde for assistance with NMR spectroscopy. We thank Heidi Clements, Hannah Bailey, and Joshua Castleman (Dow) for assistance in collecting polymer characterization data (GPC, DSC, FT-IR). We thank Todd Senecal and Steve Marshall (Dow) for assistance in collecting batch reactor data. Support has been provided for the X-ray diffraction and NMR instrumentation via the Dow Next Generation Educator Fund. X.Z. and T.F.M. acknowledge the computational resources from the Extreme Science and Engineering Discovery Environment (XSEDE) Bridges computer at the Pittsburgh Supercomputing Center through allocation TG-MCB160013. Author Contributions: S.X., M.M.S., and X.Z. contributed equally. The authors declare the following competing financial interest(s): A patent application including ligand 1 was filed.
Funders:
Funding AgencyGrant Number
Dow Chemical CompanyUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Agency for Science, Technology and Research (A*STAR)UNSPECIFIED
Dow Next Generation Educator FundUNSPECIFIED
NSFTG-MCB160013
Issue or Number:17
DOI:10.1021/jacs.1c00566
Record Number:CaltechAUTHORS:20210430-120931834
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20210430-120931834
Official Citation:Efficient Copolymerization of Acrylate and Ethylene with Neutral P, O-Chelated Nickel Catalysts: Mechanistic Investigations of Monomer Insertion and Chelate Formation. Shuoyan Xiong, Manar M. Shoshani, Xinglong Zhang, Heather A. Spinney, Alex J. Nett, Briana S. Henderson, Thomas F. Miller, and Theodor Agapie. Journal of the American Chemical Society 2021 143 (17), 6516-6527; DOI: 10.1021/jacs.1c00566
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108902
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:30 Apr 2021 20:09
Last Modified:10 May 2021 20:42

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