title: Isoprene polymerization mediated by vanadium-[ONNO] complexes.
abstract: A series of vanadium complexes bearing dianionic tetradentate amine-bisphenolate [ONNO] ligands, V([double bond, length as m-dash]O)X[ONNO(Me)] (X = Cl (1); O(i)Pr (2)), VCl2[ONNO(Me)] (3) and V(O(i)Pr)2[ONNO(R)] (R = Me (4), (t)Bu (5), Cl (6)), displaying various electronic and steric properties have been prepared. The molecular structures of two of these complexes, namely V[ONNO(R)](O(i)Pr)2 with R = (t)Bu (5) or Cl (6), are reported. Activated with dialkylmagnesium, all complexes lead to modest isoprene homo-polymerization activities at 50 °C. Quantitative polymerizations were observed using 4 and 6 as pre-catalysts combined with Al(i)Bu3. The resulting polyisoprene microstructure was composed of ca. 70% 3,4 enchainments, the remaining 30% 1,4 enchainments being a mixture of cis and trans stereoisomers. 6 leads to a more active catalyst than 4. β-Hydride abstraction occurs during the reaction.
authors.affiliation: UCCS, Unité de Catalyse et Chimie du Solide, CNRS, UMR8181, ENSCL, Université de Lille, F-59652 Villeneuve d'Ascq, France and Department of Chemistry, Faculty of Science, Naresuan University, Phitsanulok 65000, Thailand.
authors.forename: Yupin
authors.initials: Y
authors.lastname: Phuphuak
authors.affiliation: UCCS, Unité de Catalyse et Chimie du Solide, CNRS, UMR8181, ENSCL, Université de Lille, F-59652 Villeneuve d'Ascq, France.
authors.forename: Fanny
authors.initials: F
authors.lastname: Bonnet
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, F-31077 Toulouse, France. lorber@lcc-toulouse.fr and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France.
authors.forename: Laure
authors.initials: L
authors.lastname: Vendier
authors.affiliation: CNRS, LCC (Laboratoire de Chimie de Coordination), 205 route de Narbonne, F-31077 Toulouse, France. lorber@lcc-toulouse.fr and Université de Toulouse, UPS, INPT, LCC, F-31077 Toulouse, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Lorber
authors.affiliation: UCCS, Unité de Catalyse et Chimie du Solide, CNRS, UMR8181, ENSCL, Université de Lille, F-59652 Villeneuve d'Ascq, France.
authors.forename: Philippe
authors.initials: P
authors.lastname: Zinck