title: Introducing "Ynene" Metathesis: Ring-Expansion Metathesis Polymerization Leads to Highly Cis and Syndiotactic Cyclic Polymers of Norbornene.
abstract: Tungsten alkylidynes [CF3-ONO]W≡CC(CH3)3(THF)2 (1) and [(t)BuOCO]W≡CC(CH3)3(THF)2 (3) react with ethylene. Complex 1 reacts reversibly with ethylene to give the metallacyclobutene (2). Complex 3 reacts with ethylene to form the tethered alkylidene (4) featuring a tetraanionic pincer ligand. Complexes 1 and 3 initiate the polymerization of norbornene at room temperature. The polymerization of norbornene by 1 is not stereoselective, whereas 3 generates a highly cis and syndiotactic cyclic polynorbornene. Comparison of the intrinsic viscosity, radius of gyration, and elution time of the synthesized cyclic polynorbornene with those of linear analogues provides conclusive evidence for a cyclic topology.
authors.affiliation: Center for Catalysis, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Soufiane S
authors.initials: SS
authors.lastname: Nadif
authors.affiliation: Center for Macromolecular Science & Engineering and George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Kubo
authors.affiliation: Center for Catalysis, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Stella A
authors.initials: SA
authors.lastname: Gonsales
authors.affiliation: Center for Catalysis, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Sudarsan
authors.initials: S
authors.lastname: VenkatRamani
authors.affiliation: Center for Catalysis, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.|Center for Macromolecular Science & Engineering and George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Ion
authors.initials: I
authors.lastname: Ghiviriga
authors.affiliation: Center for Macromolecular Science & Engineering and George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Brent S
authors.initials: BS
authors.lastname: Sumerlin
authors.affiliation: Center for Catalysis, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.|Center for Macromolecular Science & Engineering and George & Josephine Butler Polymer Research Laboratory, Department of Chemistry, University of Florida , P.O. Box 117200, Gainesville, Florida 32611, United States.
authors.forename: Adam S
authors.initials: AS
authors.lastname: Veige