Abstract: The catalyst systems, for selective trimerization of ethylene are of great industrial and academic interest, since 1-hexene is used as a comonomer for linear-low-density polyethylene production. The titanium(IV) complex LTiCl3 bearing a substituted phenoxy-imine ligand L activated with MAO produced 1-hexene with high activity and selectivity. The presented work is aimed at NMR and EPR spectroscopic study of the Ti(IV), Ti(III) and Ti(II) species formed upon activation of the pre-catalyst LTiIVCl3 with various activators (MAO, MMAO, AlR3/[CPh3]+[B(C6F5)4]-, R = Me, Et, iBu) to elucidate possible role of the observed titanium species in ethylene trimerization and polymerization reactions. It was found that Ti(IV) complexes [LTiIVMe2]+[A], and Ti(II) complexes of the type [LTiII(S)]+[A]- ([A]- = counter ion, S = solvent or vacancy) participate in the selective ethylene trimerization process, whereas Ti(III) species of the type [LTiIII(μ-H)(μ-Cl)AliBu2]+[MeMMAO] and [LTiIII(μ-Me)(μ-Cl)AliBu2]+[MeMMAO]- can promote undesirable PE formation.

Cite: Soshnikov I.E. , Semikolenova N.V. , Bryliakov K.P. , Zakharov V.A. , Talsi E.P.
Selective Ethylene Trimerization by Titanium Complexes Bearing Phenoxy-Imine Ligands with Pendant Arm: NMR- and EPR-Spectroscopic Study of the Reaction Intermediates
EuropaCat-XII: 12th European Congress on Catalysis “Catalysis: Balancing the use of fossil and renewable resources” 30 Aug - 4 Sep 2015