Synthesis and Characterization of Imino‐Phenolate Titanium Complexes and Their Use in Homo‐ and Copolymerization of Ethylene

Abstract

A set of titanium precatalysts [(L)TiCl3] based on imino‐phenolate tridentate ligands (Ti1, L = 3,5‐tBu‐2‐(OH)C6H2CH‐N‐8‐C9H6N; Ti2, L = 3,5‐tBu‐2‐(OH)C6H2CH‐N‐C2H4‐O‐C6H5; Ti3, L = 3,5‐tBu‐2‐(OH)C6H2CH‐N‐CH2‐C6H4OMe; Ti4, L = 3,5‐tBu‐2‐(OH)C6H2CH‐N‐C6H4‐C6H5O) is prepared and characterized by elemental analysis, IR, and NMR spectroscopy. Upon activation with methylaluminoxane (MAO), these precatalysts show good activity (200–660 kg of PE mol[Ti]−1 h−1 at 60 °C) in ethylene polymerization yielding high‐density poly­ethylenes (HDPEs) with viscosity‐average molecular weight (Mv) in the range between 184 and 355 × 103 g mol−1. The Mv values of the resulting polyethylenes indicate strong influence of the aluminum concentration on the molecular weight, which can be associated to the probability of chain transfer from titanium to aluminum at high [Al]/[Ti] molar ratios. The polydispersity index (PDI) calculated from Gc(ωc) values are broad (24 to >40) indicating the multisite nature of this class of titanium precatalysts. Ti1–Ti4 are also tested in the copolymerization of ethylene with 1‐hexene affording high‐molecular‐weight poly(ethylene‐co‐1‐hexenes) with comonomer incorporation varying from 1.0 to 4.1 mol%. The crystallization analysis fractionation (CRYSTAF) profiles of copolymers produced by Ti2–Ti3 indicate the production of HDPE with very low efficiency (quantity and distribution) on incorporating 1‐hexene. On the other hand, the polymer produced by Ti1 shows a broad peak of branching fraction with different amount and comonomer distribution, suggesting a good 1‐hexene distribution along of main polymer chain.

Polypropylene and poly(ethylene-co -1-octene) effective synthesis with diamine-bis(phenolate) complexes: Effect of complex structure on catalyst activity and product microstructure

“…All the complexes under given conditions gave copolymers, yet their activity was somewhat lower than that for ethylene polymerization. That makes a typical example of a negative comonomer effect on the activity of the catalytic systems which was observed earlier for other organometallic systems, both metallocene and post‐metallocene ones . The titanium catalyst composition had a small impact on the polymer yield but, as expected, the comonomer incorporation depended on the ligand structure.…”

Facile synthesis of novel NNO-tethered copper(ii) complexes: characterization details, theoretical studies, promising enzyme-like activities, and biomolecular interactions

“…The quinoline-based salicylaldimine Schiff base ligand ( LH ) with nitrogen and oxygen donor atoms was synthesized and characterized following a reported method. 60 A methanol solution of the LH , upon reaction with copper( ii ) perchlorate hexahydrate under stirring, was followed by the addition of ammonium thiocyanate (NH 4 SCN) in a 1 : 1 : 1 molar ratio, which yielded the complex [Cu(L)(NCS)] ( 1 ). Complex [Cu(L)(N 3 )] ( 2 ) was prepared by a procedure similar to that given in the case of 1 , but with the addition of sodium azide (NaN 3 ) instead of NH 4 SCN to the reaction mixture.…”

The 60th Birthday of Prof. Minoru Terano

“…The 60th Birthday of Prof. Minoru Terano www.mcp-journal.de over conventional Ziegler-Natta [1] and newly developed single-site catalytic systems, [2] further development of the Phillips system, [3] and fi nely tuned metallocence systems. [4] Moreover, late-transition-metal complexes are promising for industrial processes producing novel advanced polyolefi n materials, [5] while computation simulation is promising for the design and prediction of effective catalysts, along with the production of advanced polyolefi ns.…”