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Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins

Radlauer, Madalyn R. and Day, Michael W. and Agapie, Theodor (2012) Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins. Organometallics, 31 (6). pp. 2231-2243. ISSN 0276-7333. PMCID PMC3375993. http://resolver.caltech.edu/CaltechAUTHORS:20120420-144952369

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Abstract

Dinuclear nickel phenoxyiminato olefin polymerization catalysts based on rigid p-terphenyl frameworks are reported. Permethylation of the central arene of the terphenyl unit and oxygen substitution of the peripheral rings ortho to the aryl–aryl linkages blocks rotation around these linkages, allowing atropisomers of the ligand to be isolated. The corresponding syn and anti dinickel complexes (25-s and 25-a) were synthesized and characterized by single-crystal X-ray diffraction. These frameworks limit the relative movement of the metal centers, restricting the metal–metal distance. Kinetics studies of isomerization of a ligand precursor (7-a) allowed the calculation of the activation parameters for the isomerization process (ΔH^‡ = 28.0 ± 0.4 kcal × mol^(–1) and ΔS^‡ = −12.3 ± 0.4 cal mol^(–1) K^(–1)). The reported nickel complexes are active for ethylene polymerization (TOF up to 3700 (mol C_2H_4) (mol Ni)^(−1) h^(–1)) and ethylene/α-olefin copolymerization. Only methyl branches are observed in the polymerization of ethylene, while α-olefins are incorporated without apparent chain walking. These catalysts are active in the presence of polar additives and in neat tetrahydrofuran. The syn and anti isomers differ in polymerization activity, polymer branching, and polymer molecular weight. For comparison, a series of mononuclear nickel complexes (26, 27-s, 27-a, 28, 30) was prepared and studied. The effects of structure and catalyst nuclearity on reactivity are discussed.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1021/om2011694DOIArticle
http://pubs.acs.org/doi/abs/10.1021/om2011694PublisherArticle
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3375993/PubMed CentralArticle
ORCID:
AuthorORCID
Agapie, Theodor0000-0002-9692-7614
Additional Information:© 2012 American Chemical Society. Received: November 22, 2011. Publication Date (Web): March 8, 2012. We thank Lawrence M. Henling (Caltech) for assistance with collection of crystallographic data and Jerzy Klosin (Dow Chemical) for the collection of GPC data. We are grateful to Dow Chemical and Caltech for funding. The Bruker KAPPA APEXII X-ray diffractometer was purchased via an NSF CRIF:MU Award to Caltech (Grant No. CHE-0639094). The 400 MHz NMR spectrometer was purchased via an NIH award (No. RR027690).
Funders:
Funding AgencyGrant Number
Dow Chemical Company UNSPECIFIED
CaltechUNSPECIFIED
NSFCHE-0639094
NIHRR027690
PubMed Central ID:PMC3375993
Record Number:CaltechAUTHORS:20120420-144952369
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20120420-144952369
Official Citation:Dinickel Bisphenoxyiminato Complexes for the Polymerization of Ethylene and α-Olefins Madalyn R. Radlauer, Michael W. Day, and Theodor Agapie Organometallics 2012 31 (6), 2231-2243
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:30244
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:20 Apr 2012 22:23
Last Modified:05 May 2017 21:30

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