Homo- and Copolymerization of Ethylene with Norbornene Catalyzed by Vanadium(III) Phosphine Complexes

Abstract

Herein, we report the homo- and co-polymerization of ethylene (E) with norbornene (NB) catalyzed by vanadium(III) phosphine complexes of the type VCl3(PMenPh3-n)2 [n = 2 (1a), 1 (1b)] and VCl3(PR3)2 [R = phenyl (Ph, 1c), cyclohexyl (Cy, 1d), tert-butyl (tBu, 1e)]. In the presence of Et2AlCl and Cl3CCOOEt (ETA), 1a–1e exhibit good activities for the polymerization of ethylene, affording linear, semicrystalline PEs with a melting temperature of approximately 130 °C. Mainly alternating copolymers with high comonomer incorporation were obtained in the E/NB copolymerization. A relationship was found between the electronic and steric properties of the phosphine ligands and the catalytic performance. Overall, the presence of electron-withdrawing ligand substituents increases the productivity, complexes with aryl phosphine (weaker σ–donor character) exhibiting a higher (co)polymerization initiation rate than those with alkyl phosphines (stronger σ–donor character). Steric effects also seem to play a key role since 1d and 1e, having large size phosphines (PCy3 θ = 170° and PtBu3 θ = 182°, respectively) are more active than 1a (PMe2Ph θ = 122°). In this case, the larger size of PtBu3 and PCy3 likely compensates for their higher donor strength compared to PMe2Ph.

Copolymerization of ethylene with propylene and higher α-olefins catalyzed by (imido)vanadium(iv) dichloride complexes

“…21 The recent resurgence of vanadium stems from the use of Schiff−base phenoxyimine−type ligands by Fujita at Mitsui. 13 Since then, a set of vanadium complexes supported by mono-and multi-dentate ligands, [22][23][24] including phenoxyimines, 25 aryloxides, 26 β−enaminoketonato, 27 diaminebis(phenolate), 28 bis(arylimo)acenaphthene, 29 phosphine, [30][31][32] oxazoline, 33 and N-heterocyclic carbenes 34 have been successfully developed. In this framework, we recently reported the synthesis of a set of phosphine adducts of (imido)V(IV) complexes, and we demonstrated their successful application as catalyst precursors for the copolymerization of ethylene with cyclic olefins.…”

Vanadium catalysts for ethylene-norbornene copolymerization

“…In addition, the relatively low cost and large variety of phosphines encourage the development of metal-phosphine complexes. The vanadium(III) (I-VII) and vanadium(IV) (VIII-X) catalysts with phosphine ligands used in the Et-NB copolymerization are complexes with monodentate and bidentate ligands [30,[52][53][54].…”

Structural and Thermal Properties of Ethylene-Norbornene Copolymers Obtained Using Vanadium Homogeneous and SIL Catalysts

“…To prevent this, ethyl trichloroacetate (ETA) reactivator is often used. Another method of stabilizing the vanadium active center is applying ligands with electron-donating atoms, oxygen or nitrogen [ 14 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 ]. In our previous works it was found that the vanadium metallocene and post-metallocene catalysts with oxazoline ligand activated by the traditional organoaluminium compound (AlEt 2 Cl) and ETA can be successfully used for COC synthesis [ 35 , 36 , 37 , 38 , 39 , 40 , 41 ].…”