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dc.contributor.authorYan, Tao
dc.contributor.authorVenkatRamani, Sudarsan
dc.contributor.authorSchrock, Richard R.
dc.contributor.authorMüller, Peter
dc.date.accessioned2020-05-01T18:57:17Z
dc.date.available2020-05-01T18:57:17Z
dc.date.issued2019-08
dc.date.submitted2019-06
dc.identifier.issn0276-7333
dc.identifier.issn1520-6041
dc.identifier.urihttps://hdl.handle.net/1721.1/124980
dc.description.abstractWe have synthesized and characterized tungsten oxo alkylidene biphenolate complexes with the formulas W(O)(CHR)(rac-biphenolate)(PPhMe2) and (R,S)-[W(μ-O)(CHR)(biphenolate)]2 (R = CMe2Ph; biphenolate = L1 or L2 in the text). They behave as initiators for the stereoselective (cis,isotactic) polymerization of 2,3-dicarbomethoxy-5-norbornadiene and eight enantiomerically pure 5-substituted norbornenes with a cis,isotactic precision of 95–98% in most cases. The active initiators are 14e W(O)(CHR)(biphenolate) complexes, which are formed through either dissociation of PPhMe2 from the phosphine adducts or scission of the heterochiral dimer. Addition of B(C6F5)3 (one per W) to (R,S)-[W(μ-O)(CHR)(L1)]2 led to formation of what we propose to be monomeric W[OB(C6F5)3](CHR)(L1) in equilibrium with B(C6F5)3 and (R,S)-[W(μ-O)(CHR)(L1)]2. This mixture decomposed over a period of 1–2 h, was much slower to initiate polymerization than (R,S)-[W(μ-O)(CHR)(L1)]2, and was much less stereoselective. Polymerization of five of the monomers with the imido alkyidene initiator, W(N-2,6-Me2C6H3)(CHCMe2Ph)(rac-L1), gave virtually identical results compared to the results obtained with oxo complexes.en_US
dc.description.sponsorshipNational Science Foundation (CHE-1463707)en_US
dc.publisherAmerican Chemical Society (ACS)en_US
dc.relation.isversionofhttp://dx.doi.org/10.1021/acs.organomet.9b00377en_US
dc.rightsCreative Commons Attribution-NonCommercial-NoDerivs Licenseen_US
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/en_US
dc.sourceACSen_US
dc.titleSynthesis of Tungsten Oxo Alkylidene Biphenolate Complexes and Ring-Opening Metathesis Polymerization of Norbornenes and Norbornadienesen_US
dc.typeArticleen_US
dc.identifier.citationYan, Tao et al. "Synthesis of Tungsten Oxo Alkylidene Biphenolate Complexes and Ring-Opening Metathesis Polymerization of Norbornenes and Norbornadienes." Organometallics 38, 16 (August 2019): 3144-3150 © 2019 American Chemical Societyen_US
dc.contributor.departmentMassachusetts Institute of Technology. Department of Chemistryen_US
dc.relation.journalOrganometallicsen_US
dc.eprint.versionFinal published versionen_US
dc.type.urihttp://purl.org/eprint/type/JournalArticleen_US
eprint.statushttp://purl.org/eprint/status/PeerRevieweden_US
dspace.date.submission2019-11-25T19:39:05Z
mit.journal.volume38en_US
mit.journal.issue16en_US


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