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dc.contributor.authorXia, Wei
dc.contributor.authorSalmeia, Khalifah A.
dc.contributor.authorVagin, Sergei I.
dc.contributor.authorRieger, Bernhard
dc.date.accessioned2016-02-25T12:57:23Z
dc.date.available2016-02-25T12:57:23Z
dc.date.issued2015-02-05
dc.identifier.citationXia W, Salmeia KA, Vagin SI, Rieger B (2015) Concerning the Deactivation of Cobalt(III)-Based Porphyrin and Salen Catalysts in Epoxide/CO 2 Copolymerization . Chem Eur J 21: 4384–4390. Available: http://dx.doi.org/10.1002/chem.201406258.
dc.identifier.issn0947-6539
dc.identifier.pmid25656829
dc.identifier.doi10.1002/chem.201406258
dc.identifier.urihttp://hdl.handle.net/10754/597827
dc.description.abstract© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Functioning as active catalysts for propylene oxide (PO) and carbon dioxide copolymerization, cobalt(III)-based salen and porphyrin complexes have drawn great attention owing to their readily modifiable nature and promising catalytic behavior, such as high selectivity for the copolymer formation and good regioselectivity with respect to the polymer microstructure. Both cobalt(III)-salen and porphyrin catalysts have been found to undergo reduction reactions to their corresponding catalytically inactive cobalt(II) species in the presence of propylene oxide, as evidenced by UV/Vis and NMR spectroscopies and X-ray crystallography (for cobalt(II)-salen). Further investigations on a TPPCoCl (TPP=tetraphenylporphyrin) and NaOMe system reveal that such a catalyst reduction is attributed to the presence of alkoxide anions. Kinetic studies of the redox reaction of TPPCoCl with NaOMe suggests a pseudo-first order in cobalt(III)-porphyrin. The addition of a co-catalyst, namely bis(triphenylphosphine)iminium chloride (PPNCl), into the reaction system of cobalt(III)-salen/porphyrin and PO shows no direct stabilizing effect. However, the results of PO/CO2 copolymerization by cobalt(III)-salen/porphyrin with PPNCl suggest a suppressed catalyst reduction. This phenomenon is explained by a rapid transformation of the alkoxide into the carbonate chain end in the course of the polymer formation, greatly shortening the lifetime of the autoreducible PO-ring-opening intermediates, cobalt(III)-salen/porphyrin alkoxides. CO2 saves: The deactivation of cobalt(III)-porphyrin and salen catalysts in propylene oxide/carbon dioxide copolymerization is systematically investigated, revealing a proposed mechanism for the catalyst reduction (see scheme).
dc.description.sponsorshipW.X. and K.A.S. thank the King Abdullah University of Science and Technology (KAUST) for the financial support of this work (UK-C0020/KSA-C0069).
dc.publisherWiley
dc.subjectCarbon dioxide
dc.subjectCatalyst deactivation
dc.subjectCobalt
dc.subjectEpoxides
dc.subjectRing-opening polymerization
dc.titleConcerning the Deactivation of Cobalt(III)-Based Porphyrin and Salen Catalysts in Epoxide/CO 2 Copolymerization
dc.typeArticle
dc.identifier.journalChemistry - A European Journal
dc.contributor.institutionTechnische Universitat Munchen, Munich, Germany
dc.contributor.institutionForschungsinstitution fur Materialwissenschaften Und Technologie Eth-Bereichs, Dubendorf, Switzerland
kaust.grant.numberUK-C0020/KSA-C0069
dc.date.published-online2015-02-05
dc.date.published-print2015-03-09


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