ansa-Cyclopentadienyl-Phenoxy Titanium(IV) Complexes (PHENICS): Synthesis, Characterization, and Catalytic Behavior in Olefin Polymerization

Abstract

A series of ansa-cyclopentadienyl-phenoxy titanium complexes (PHENICS: phenoxy-induced complex of Sumitomo) (1a-e), [{Me 2 CCp(OC 6 H 2 -3-R-5-R 0 )}TiCl 2 ] (1a, R = R 0 = H; 1b, R = t Bu, R 0 = Me) and [{Me 2 Si(C 5 Me 4 )(OC 6 H 2 -3-R 00 -5-Me)}TiCl 2 ] (1c, R 00 = i Pr; 1d, R 00 = t Bu; 1e, R 00 = Adm), have been synthesized and characterized. It is noteworthy that the dihedral angles of the cyclopentadienyl and phenoxy moieties of the complexes 1b and 1d, revealed by X-ray crystal structure analysis, are 63.0°(1b) and 68.2°(1d), indicating a distortion from a mutual perpendicular arrangement, whereas the symmetrical patterns of the 1 H NMR spectra indicate a dynamic behavior in solution. The PHENICS-type complexes exhibit good to excellent catalytic activities for copolymerization of ethylene and 1-hexene upon activation with Al i Bu 3 /[Ph 3 C][B(C 6 F 5 ) 4 ] cocatalyst. Particularly, the complexes with a bulky substituent at the ortho position of the phenoxy moiety showed excellent catalytic features (1d, 27 200 kg mol -1 h -1 at 80 °C, 6000 kg mol -1 h -1 at 180 °C). These data show that the catalytic activity of the PHENICS-type catalysts is higher than that reported for the so-called constrained geometry catalyst (CGC) precursors. This becomes even more evident in light of the results for polymerization at 180 °C. Whereas the PHENICS catalyst system acts as a single-site catalyst at 180 °C, the CGC-type catalysts proved to be inactive under analogous conditions. Moreover, the copolymers obtained with PHENICS incorporate much higher content of 1-hexene than those obtained with CGC.

Synthesis and structures of adamantyl-substituted constrained geometry cyclopentadienyl–phenoxytitanium complexes and their catalytic properties for olefin polymerization

“…Adequately bulky ligand would weaken the interaction between the cationic catalyst and the anionic cocatalyst [16,35], therefore could favor the coordination of the olefins and increase the catalytic activity of the catalyst. Similar results have previously been observed for ethylene/1-hexene copolymerization reaction with other half-metallocene titanium(IV) catalyst systems [19,40,41]. With 9/ TIBA/B catalyst system, copolymerization experiments with different 1-hexene feed concentrations were carried out and obvious comonomer effect was observed.…”

Post‐Metallocenes in the Industrial Production of Polyolefins

“…A related catalyst system for LLDPE production, termed PHENICS (phenoxy‐induced complex of Sumitomo), was developed by Sumitomo Chemical (Figure 6). 65, 66 These catalysts typically possess a silicon‐bridged cyclopentadienyl phenoxy ligand coordinating to a Ti IV center. When complex 7 is activated with i Bu 3 Al/[Ph 3 C][B(C 6 F 5 ) 4 ] high‐molecular‐weight ethylene/1‐hexene copolymers are obtained with an activity of 2.7×10 7 g(polymer) mol(Ti) −1 h −1 at a polymerization temperature of 80 °C.…”

Supported permethylindenyl titanium catalysts for the synthesis of disentangled ultra-high molecular weight polyethylene (disUHMWPE)

“…An improvement in activity is reported over CGC catalysts, particularly at high temperature, with single-site catalytic behaviour maintained above 200 1C. [13][14][15][16] Herein, we report the efficient synthesis of a new family of permethylindenyl (Ind*, I*) phenoxide (PHENI*) ansa-metallocenes, and their subsequent immobilisation on various inorganic supports (silica, LDH, and sMAO) to afford highly active solid catalysts. We report their use in slurry-phase polymerisation of ethylene, with extremely high activities, desirable polymer morphology, and the production of ultra-high molecular weight polyethylene (UHMWPE, M w 4 1 MDa).…”