Zirconium Complexes with Bulkier Amine Bis(phenolate) Ligands and Their Catalytic Properties for Ethylene (Co)polymerization

Abstract

A series of new zirconium complexes bearing bulkier amine bis­(phenolate) tetradentate ligands, Me2NCH2CH2N­{CH2(2-O-3-R-5- t Bu-C6H2)}2ZrCl2 [R = CPhMe2 (1); CMePh2 (2); CPh3 (3); Ph (4); 3,5-Me2C6H3 (5); 3,5- t Bu2C6H3 (6); 4- t BuC6H4 (7)], were synthesized and characterized by 1H nuclear magnetic resonance (NMR), 13C NMR, and elemental analyses. The molecular structures of complexes 1 and 3 were determined by single-crystal X-ray diffraction analysis. The X-ray crystallography analysis reveals that these complexes display a slightly distorted octahedral geometry around their metal centers. Upon activation with methylaluminoxane (MAO), dry-MAO, MAO/butylated hydroxytoluene (BHT), or Al i Bu3/CPh3B­(C6F5)4, these zirconium complexes exhibit high catalytic activity for ethylene polymerization [up to 1.07 × 107 g PE (mol Zr)−1 h–1] and ethylene/1-hexene copolymerization [up to 2.78 × 107 g polymer (mol Zr)−1 h–1], affording (co)­polymers with moderate to high molecular weights and good comonomer incorporations. The zirconium complexes with bulkier R groups show higher catalytic activities and longer lifetimes and produce polymers with higher molecular weights, while the zirconium complexes with aryls as R groups demonstrate relatively good comonomer incorporation ability for the copolymerization reactions. These catalytic systems also show moderate catalytic activities for the polymerization reactions of propylene, 1-hexene, and 1-decene. Upon activation with MAO, the zirconium complexes also show moderate catalytic activities for the copolymerization reaction of ethylene with 3-buten-1-ol (treated with 1 equiv of Al i Bu3), affording copolymers with the incorporation of 3-buten-1-ol up to 1.05%.

Enhancement of Ethylene and Ethylene/1-Hexene (Co)polymerization Activities by Titanium(IV) and Zirconium(IV) Complexes Bearing Constrained Hydroxyindanone-Imine Ligands

“…The incorporation of 1-hexene into the polymers is reported in Table . Generally, the melting temperature ( T m ) of the copolymers decreases as the 1-hexene content increases in the temperature range of 106–117 °C for 1-hexene content of 1.7–8.6 mol % (Table , entries 2–6), comparable to the reported values. − The 1-hexene content in the copolymers also decreases as the steric hindrance increases. Therefore, complex 1 , being the least hindered, produced the copolymer having the highest 1-hexene content of 15.9 mol % (Table , entry 1).…”

Synthesis of Ultrahigh Molecular Weight Ethylene-Based (Co)polymers with Titanium Complexes Bearing Nonsymmetric Amine-bis(phenolate) Ligands

“…3a and 4a were synthesized by a similar procedure described in literature for 2a . NBS (9.08 g, 51.0 mmol) was mixed with 20 mL of dichloromethane to form a suspension, which was then added dropwise to a solution of 2-R 1 -4-( tert -butyl)-phenol (50.0 mmol) in 50 mL of dichloromethane at room temperature.…”

“…So far, most of the mononuclear IIA and IIB type of titanium and zirconium complexes were reported to exhibit very low catalytic activities for ethylene polymerization. – ,, Some of the complexes II were reported to demonstrate low to moderate catalytic activities for ethylene/1-olefine copolymerization reactions with the production of copolymers having moderate comonomer incorporations. – ,, Recently, our group synthesized a series of titanium and zirconium complexes of the type IIA with R 1 = R 2 being bulky substituents and found that the zirconium complexes exhibit high catalytic activities for both ethylene polymerization and ethylene/1-olefin copolymerization reactions. The zirconium complexes are capable of producing polymers with moderate to high molecular weights and comonomer incorporations, while the titanium complexes show relatively low catalytic activities and produce copolymers with low comonomer incorporations due probably to the coordinating environment around the titanium atom being too crowded . On the other hand, high to ultrahigh molecular weight polyethylene (PE) and polyolefin thermoplastic elastomer (POE) or linear low density PE (LLDPE) have attracted much attention because these unique polymers have outstanding physical and mechanical properties .…”

Synthesis of Si‐O‐Si bridged diamido Group 4 complexes and the applications to polymerization of olefins

“…In this connection, diverse ligand frameworks based on cyclopentadienyl [17], amide [18,19], and phenoxy derivatives [5,20] have been developed. While Cp-based metallocene catalysts have been extensively studied in the past several decades, non-Cp ligands based on nitrogen, oxygen, and other heteroatoms provided alternative and diverse solutions for a great number of catalytic processes such as copolymerization reactions [1,4,[20][21][22][23][24]. Recent studies have shown that Group 4 catalysts supported by non-Cp family of ligands could provide many new opportunities for the synthesis of new polyolefins by copolymerization reactions [15,25].…”