Titanium Complexes of Silicon-Bridged Cyclopentadienyl−Phenoxy Ligands Modified with Fused-Thiophene: Synthesis, Characterization, and Their Catalytic Performance in Copolymerization of Ethylene and 1-Hexene

Abstract

dithiophenyl}, were prepared by treating TiCl 4 with the dilithium salts generated by reaction of the corresponding ligands (3, 4, 7, 8, and 11-15) with n BuLi in the presence of Et 3 N in toluene. In the ligand synthesis, the use of, respectively. X-ray crystallographic studies of 6, 17, and 19 indicate that the cyclopentadienyl moiety of 6 with TFCp (TFCp = thiophene-fused cyclopentadienyl) is bound to the titanium atom in an η 5 -fashion, whereas the coordination of the moieties to the metal in 17 and 19 with DTFCp (DTFCp = dithiophene-fused cyclopentadienyl) contributes in somewhat of an η 3 -manner. The newly prepared complexes 5, 6, 9, 10, and 16-20 exhibited high catalytic activities for copolymerization of ethylene and 1-hexene in the presence of i Bu 3 Al/[Me 2 NHPh][B(C 6 F 5 ) 4 ] and afforded higher molecular weight copolymer than the parent tetramethyl-substituted cyclopentadienyl complex Me 2 Si(η 5 -C 5 Me 4 )(3-t Bu-5-Me-2-C 6 H 2 O)TiCl 2 (1a). The complexes 6, 17, and 19 were thermally stable and exhibited high polymerization activities, even at 180 °C. Among tested complexes, the DTFCp complexes 17 and 19 at 180 °C showed very high activity and produced high molecular weight copolymers with good 1-hexene content.

Post‐Metallocenes in the Industrial Production of Polyolefins

“…Increasing the steric bulk of these substituents hampers 2,1‐insertion in propylene homopolymerization and leads to higher molecular weights 67. Further catalyst optimization lead to complexes bearing thiophene‐fused cyclopentadienyl moieties68 or a fluorenyl ligand,69 which were highly active in producing high‐molecular‐weight ethylene/1‐hexene copolymers with high 1‐hexene content even at temperatures up to 210 °C.…”

Preparation of Thiophene-Fused and Tetrahydroquinoline-Linked Cyclopentadienyl Titanium Complexes for Ethylene/α-Olefin Copolymerization

“…The 1 H NMR spectrum indicated a mixture of two stereoisomers in 1:0.9 ratio. 1 H NMR (C 6 D 6 ): δ 7.11 (t, J = 4.4 Hz, 1H), 6.90 (d, J = 5.6 Hz, 2H), 6 …”

“…It produces a higher-molecular-weight polymer and also exhibits greater thermal stability [22]. Other metallocenes and half-metallocenes prepared using thiophene-fused cyclopentadienyls display the same trend in their catalytic performances [6,[23][24][25]. These features allow higher temperature to be used, which is a merit when performing the solution process.…”

“…Now, there is a bright industrial future for metallocene catalysts. Kaminsky's initial bis(cyclopentadienyl)-type metallocene catalysts were later expanded to half-metallocene catalysts, which are titanium(IV) complexes coordinated by a cyclopentadienyl-type ligand and an amido-type ligand [3][4][5][6][7][8][9]. A typical representative of the half-metallocene catalysts is the constrained-geometry catalyst (CGC) [Me 2 Si(η 5 -Me 4 C 5 )(N t Bu)]TiCl 2 [10][11][12].…”

A new post-metallocene catalyst for alkene polymerization: copolymerization of ethylene and 1-hexene with titanium complexes bearingN,N-dialkylcarbamato ligands

“…At the present time, the focus of attention in alkene polymerization chemistry has shifted to soluble post‐metallocene catalysts based on a variety of multi‐dentate complexes of transition metals. Several studies describing the use of different non‐metallocene complexes of group 4 transition metals in ethylene copolymerization reactions have been reported in the literature; some of the catalysts are employed on an industrial scale …”