Copolymerization of ethylene with cycloolefins by titanium complexes containing tridentate [o⁻NS^R] ligands

Abstract

A family of titanium complexes of the general formula [N‐(3,5‐di‐tert‐butylsalicylidene)‐2‐alkylsulfanylanilinato]Ti(IV)Cl3 5a–f was prepared from the reaction of TiCl4 with the potassium salts of the corresponding ligands. These complexes were fully characterized by various spectroscopic techniques and elemental analyses. The molecular structures of 5b and 5e were further confirmed by single‐crystal X‐ray analyses. Complexes 5a–f (except for 5c) exhibited good to high catalytic activities in ethylene copolymerization with cycloolefins such as norbornene, cyclopentene, dicyclopentadiene in the presence of modified methylaluminoxane. The reaction conditions and the steric hindrance of the alkyl substituents on sulfur atom in the precatalysts influenced strongly the copolymerization behaviors and the structures of the resultant copolymers. Complex 5c with bulky tert‐butylthio sidearm showed both low catalytic activity and comonomer incorporation ratio. The n‐alkylthio complexes 5a, 5d–f all exhibited good ethylene copolymerization capabilities with cycloolefins, which is superior to the corresponding phenylthio complex 5g. © 2008 Wiley Periodicals, Inc. JPolym Sci Part A: Polym Chem 46: 2807–2819, 2008

Well-defined vanadium complexes as the catalysts for olefin polymerization

“…A remarkable decrease in catalytic activity of 6a-d (at 30 min more than 70% of activity was reduced in contrast with that at 5 min) was observed, whereas catalysts 6e-f, 7 and 8 bearing softer second-row donors (S, P) showed a smaller decrease (ca. 30%), indicating the latter four catalysts possess higher thermal stability [63][64][65][66][67][68]71,72].…”

“…Enhancement of catalytic activity and/or selectivity was observed following the introduction of pendant donor groups in N,O ligands with the group IV metal catalysts; this has been proposed to arise from both steric hindrance and electronic effects [61][62][63][64][65][66][67][68]. The fast deactivation of mono(salicylaldiminato) vanadium(III) complexes took place at high polymerization temperatures, while the thermal stability of the catalysts was enhanced by the introduction of a heteroatom containing group onto the N-aryl moiety of the salicylaldiminato ligands [59,60].…”

Is imatinib mesylate a promising drug in systemic sclerosis?

“…Recent advances in the design and synthesis of the single‐site or well‐defined catalysts for olefin polymerization have promoted the discovery of several efficient catalysts for the living (co)polymerization of ethylene and/or other alkenes 3–5. The complexes of Group 4 transition metals bearing two phenoxy‐imine chelate ligands (FI catalysts) are one type of the representative nonmetallocene catalysts,6–25 which were discovered based on ligand‐oriented catalyst design 6–17. FI catalysts are capable of producing PE of low to high MW by changing the substituents near the catalytic reaction center 13.…”

Novel vanadium(III) complexes with tridentate phenoxy‐phosphine [O,P(O),O] ligands: Synthesis, characterization, and catalytic behavior of ethylene polymerization and copolymerization with 10‐undecen‐1‐ol

“…Introducing some softer second‐row donors in the ligand is another effective method to offer beneficial stabilization of the highly reactive metal center 34–41. The combination of hard donors with soft phosphine donors in early transition metal polymerization catalysis increased the configurational stability of the catalyst, which was found by Gibson34–36 and Tang 42–49. Previously, we reported the synthesis and structural characterization of a type of vanadium catalysts featuring bidentate phenoxy‐phosphine ligands, which revealed remarkable catalyst activity not only for ethylene polymerization but also for ethylene/1‐hexene copolymerization 50.…”