Control of Chain Walking by Weak Neighbouring Group Interac-tions in Unsymmetric Catalysts

Handle URI:
http://hdl.handle.net/10754/626434
Title:
Control of Chain Walking by Weak Neighbouring Group Interac-tions in Unsymmetric Catalysts
Authors:
Falivene, Laura ( 0000-0003-1509-6191 ) ; Wiedemann, Thomas; Göttker-Schnetmann, Inigo; Caporaso, Lucia; Cavallo, Luigi ( 0000-0002-1398-338X ) ; Mecking, Stefan
Abstract:
A combined theoretical and experimental study shows how weak attractive interactions of a neighbouring group can strongly promote chain walking and chain transfer. This accounts for the previously observed very different micro-structures obtained in ethylene polymerization by [κ<sup>2-N,O-{(2,6-(3',5'-R2C6H3)2C6H3-N=C(H)-(3,5-X,Y2-2-O-C6H2)}]NiCH3(pyridine)], namely hyperbranched oligomers for remote substituents R = CH3 versus. high molecular weight polyethylene for R = CF3. From a full mechanistic consideration the alkyl olefin complex with the growing chain cis to the salicylaldiminato oxygen donor is identified as the key species. Alternative to ethylene chain growth by insertion in this species, decoordination of the monomer to form a cis ß-agostic complex provides an entry into branching and chain transfer pathways. This release of monomer is promoted and made competitive by a weak η2-coordination of the distal aryl rings to the metal center, operative only for the case of sufficiently electron rich aryls. This concept for controlling chain walking is underlined by catalysts with other weakly coordinating furane and thio-phene motifs, which afford highly branched oligomers with > 120 branches per 1000 carbon atoms.
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division; KAUST Catalysis Center (KCC)
Citation:
Falivene L, Wiedemann T, Göttker-Schnetmann I, Caporaso L, Cavallo L, et al. (2017) Control of Chain Walking by Weak Neighbouring Group Interac-tions in Unsymmetric Catalysts. Journal of the American Chemical Society. Available: http://dx.doi.org/10.1021/jacs.7b08975.
Publisher:
American Chemical Society (ACS)
Journal:
Journal of the American Chemical Society
Issue Date:
20-Dec-2017
DOI:
10.1021/jacs.7b08975
Type:
Article
ISSN:
0002-7863; 1520-5126
Sponsors:
Financial support by the DFG (Me1388/14-1) and by Byk is gratefully acknowledged. Stefano Santacroce, Florian Wimmer and Giusi Boffa contributed as a part of their undergraduate studies. We thank Rainer Winter for discussions of cyclic voltammetry data.
Additional Links:
http://pubs.acs.org/doi/10.1021/jacs.7b08975
Appears in Collections:
Articles; KAUST Catalysis Center (KCC); Biological and Environmental Sciences and Engineering (BESE) Division

Full metadata record

DC FieldValue Language
dc.contributor.authorFalivene, Lauraen
dc.contributor.authorWiedemann, Thomasen
dc.contributor.authorGöttker-Schnetmann, Inigoen
dc.contributor.authorCaporaso, Luciaen
dc.contributor.authorCavallo, Luigien
dc.contributor.authorMecking, Stefanen
dc.date.accessioned2017-12-27T13:11:15Z-
dc.date.available2017-12-27T13:11:15Z-
dc.date.issued2017-12-20en
dc.identifier.citationFalivene L, Wiedemann T, Göttker-Schnetmann I, Caporaso L, Cavallo L, et al. (2017) Control of Chain Walking by Weak Neighbouring Group Interac-tions in Unsymmetric Catalysts. Journal of the American Chemical Society. Available: http://dx.doi.org/10.1021/jacs.7b08975.en
dc.identifier.issn0002-7863en
dc.identifier.issn1520-5126en
dc.identifier.doi10.1021/jacs.7b08975en
dc.identifier.urihttp://hdl.handle.net/10754/626434-
dc.description.abstractA combined theoretical and experimental study shows how weak attractive interactions of a neighbouring group can strongly promote chain walking and chain transfer. This accounts for the previously observed very different micro-structures obtained in ethylene polymerization by [κ<sup>2-N,O-{(2,6-(3',5'-R2C6H3)2C6H3-N=C(H)-(3,5-X,Y2-2-O-C6H2)}]NiCH3(pyridine)], namely hyperbranched oligomers for remote substituents R = CH3 versus. high molecular weight polyethylene for R = CF3. From a full mechanistic consideration the alkyl olefin complex with the growing chain cis to the salicylaldiminato oxygen donor is identified as the key species. Alternative to ethylene chain growth by insertion in this species, decoordination of the monomer to form a cis ß-agostic complex provides an entry into branching and chain transfer pathways. This release of monomer is promoted and made competitive by a weak η2-coordination of the distal aryl rings to the metal center, operative only for the case of sufficiently electron rich aryls. This concept for controlling chain walking is underlined by catalysts with other weakly coordinating furane and thio-phene motifs, which afford highly branched oligomers with > 120 branches per 1000 carbon atoms.en
dc.description.sponsorshipFinancial support by the DFG (Me1388/14-1) and by Byk is gratefully acknowledged. Stefano Santacroce, Florian Wimmer and Giusi Boffa contributed as a part of their undergraduate studies. We thank Rainer Winter for discussions of cyclic voltammetry data.en
dc.publisherAmerican Chemical Society (ACS)en
dc.relation.urlhttp://pubs.acs.org/doi/10.1021/jacs.7b08975en
dc.rightsThis document is the Accepted Manuscript version of a Published Work that appeared in final form in Journal of the American Chemical Society, copyright © American Chemical Society after peer review and technical editing by the publisher. To access the final edited and published work see http://pubs.acs.org/doi/10.1021/jacs.7b08975.en
dc.subjectCatalysisen
dc.subjectPolymerizationen
dc.subjectIsomerizationen
dc.subjectMechanismen
dc.subjectWeak Interactionsen
dc.subjectSelectivityen
dc.titleControl of Chain Walking by Weak Neighbouring Group Interac-tions in Unsymmetric Catalystsen
dc.typeArticleen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
dc.contributor.departmentKAUST Catalysis Center (KCC)en
dc.identifier.journalJournal of the American Chemical Societyen
dc.eprint.versionPost-printen
dc.contributor.institutionChair of Chemical Materials Science, Department of Chemistry, University of Konstanz, 78464 Konstanz, Germany.en
dc.contributor.institutionDepartment of Chemistry, University of Salerno, Via Giovanni Paolo II, 84084-Fisciano (SA), Italy.en
kaust.authorFalivene, Lauraen
kaust.authorCavallo, Luigien
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