title: Bis(phenolate)amine-supported lanthanide borohydride complexes for styrene and trans-1,4-isoprene (co-)polymerisations.
abstract: New bis(phenolate)amine-supported neodymium borohydride complexes and their previously reported samarium analogues were tested as catalysts for the polymerisation of styrene and isoprene. Reaction of Na2O2N(L) (L = py, OMe, NMe2) with Nd(BH4)3(THF)3 afforded the borohydride complexes Nd(O2N(L))(BH4)(THF) (L = py (1-Nd), OMe (2-Nd), NMe2 (3-Nd)). Complex 1-Nd has shown a propensity to form phenolate-O-bridged dimer [Nd(μ-O2N(py))(BH4)]2 (1′-Nd) as previously observed with the samarium analogues Sm(O2N(L))(BH4)(THF) (L = py or Pr). X-ray structures of 1′-Nd and 2-Nd were determined and are presented. The neodymium borohydride complexes 1-Nd to 3-Nd and their samarium analogues Sm(O2N(L))(BH4)(THF)x (L = py (1-Sm), OMe (2-Sm), NMe2 (3-Sm), Pr (4-Sm)) were tested as catalysts for the polymerisation of isoprene and styrene in the presence of n-butylethylmagnesium (Mg((n)Bu)(Et)). All complexes were found to be active for the polymerisation of isoprene in these conditions, leading to polyisoprene up to 95.1% trans-1,4 stereoregular. They were also found to be active for the polymerisation of styrene leading to atactic polystyrene in all cases. Interestingly, samarium-based complexes were found to be more active than the neodymium ones toward this latter monomer, in sharp contrast to what is usually observed with rare earth borohydride complexes. The structure of both trans-polyisoprenes and polystyrenes obtained were studied in detail by MALDI-ToF analysis in order to better understand the polymerisation mechanisms. The coordinative chain transfer polymerisation (CCTP) of both monomers was further conducted using Mg((n)Bu)(Et) as transfer agent. Finally, the statistical copolymerisation of isoprene and styrene was examined using these catalytic systems, leading to the formation of poly[(trans-1,4-isoprene)-co-styrene] with up to 39% of styrene moieties inserted in a highly trans-1,4-stereoregular polyisoprene.
authors.affiliation: Unité de Catalyse et de Chimie du Solide, CNRS, University of Lille 1, Science and Technology, 59655 Villeneuve d'Ascq, France. fanny.bonnet@ensc-lille.fr.
authors.forename: Fanny
authors.initials: F
authors.lastname: Bonnet
authors.forename: Hellen E
authors.initials: HE
authors.lastname: Dyer
authors.forename: Yassine
authors.initials: Y
authors.lastname: El Kinani
authors.forename: Carin
authors.initials: C
authors.lastname: Dietz
authors.forename: Pascal
authors.initials: P
authors.lastname: Roussel
authors.forename: Marc
authors.initials: M
authors.lastname: Bria
authors.forename: Marc
authors.initials: M
authors.lastname: Visseaux
authors.forename: Philippe
authors.initials: P
authors.lastname: Zinck
authors.forename: Philip
authors.initials: P
authors.lastname: Mountford