Toward Single-Site, Immobilized Molecular Catalysts:  Site-Isolated Ti Ethylene Polymerization Catalysts Supported on Porous Silica

2004 ◽  
Vol 126 (10) ◽  
pp. 3052-3053 ◽  
Author(s):  
Michael W. McKittrick ◽  
Christopher W. Jones
Keyword(s):  
Ethylene Polymerization ◽  
Porous Silica ◽  
Single Site ◽  
Polymerization Catalysts ◽  
Molecular Catalysts

Ethylene and 1-hexene polymerization using zirconium iminophosphonamide complexes

2006 ◽  
Vol 84 (2) ◽  
pp. 214-224 ◽  
Author(s):  
Robert Tomaszewski ◽  
Rainer Vollmerhaus ◽  
Abdulaziz Al-Humydi ◽  
Qinyan Wang ◽  
Nicholas J Taylor ◽  
...  
Keyword(s):  
Ethylene Polymerization ◽  
Room Temperature ◽  
Chain Transfer ◽  
Single Site ◽  
Complex Behavior ◽  
Polymerization Catalysts ◽  
Dichloromethane Solution ◽  
Polymerization Catalysis ◽  
Multinuclear Nmr Spectroscopy ◽  
Poly Ethylene

Ethylene polymerization was studied using a variety of iminophosphonamide (PN2) complexes of zirconium. Bis(PN2) dichloride complexes [Ph2P(NR′)2]2ZrX2 (X = Cl; 1a: R′ = p-tolyl; 1b: R′ = Bn; 1c: R′ = C6F5) or dimethyl complexes (X = Me; 2a: R′ = p-tolyl; 2b: R′ = Bn) and cyclopentadienyl(PN2)zirconium dichloride complexes [η5-C5R′′5][R2P(NR′)2]ZrCl2 (3a: R′ = p-tolyl, R = Ph, R′′ = H; 3b: R′ = SiMe3, R = Et, R′′ = H; 3c: R′ = C6F5, R = Ph, R′′ = H; 3e: R′ = 3,5-(CF3)2Ph, R = Ph, R′′ = H; 3f: R′ = 3,5-(CF3)2Ph, R = Ph, R′′ = Me) or dimethyl analogs [η5-C5H5][R2P(NR′)2]ZrMe2 (4a: R′ = p-tolyl, R = Ph; 4b: R′ = SiMe3, R = Et) were evaluated under a range of conditions using methylaluminoxane (PMAO) activator. Complexes 1 and 2 behave as precursors to single-site polymerization catalysts under the conditions studied, while complexes 3 or dialkyls 4 show more complex behavior and formation of poly(ethylene) with a bimodal molecular weight distribution. In contrast, activation of dialkyl complexes 4 with [Ph3C][B(C6F5)4] and polymerization in the presence of small amounts of PMAO or TIBAL as scavenger, led to single-site behavior. PMAO reacts with the neutral dialkyls via ligand abstraction to produce a number of P-containing species that may explain the multi-site behavior observed when using this activator. Dialkyls 4 react cleanly with [Ph3C][B(C6F5)4] in haloarene or even dichloromethane solution to furnish the corresponding cationic alkyls 5, which were characterized by multinuclear NMR spectroscopy. Fluxional dinuclear species are formed in the presence of excess dialkyl and these are susceptible to C—H activation to form µ-Me,µ-CH2 complexes one of which could be isolated in pure form. The cationic alkyls initiate the polymerization of 1-hexene at room temperature in chlorobenzene solution, but extensive chain transfer occurs and the systems are not living.Key words: single site, early metal olefin polymerization catalysis.

Doubly fused N,N,N-Iron Ethylene Polymerization Catalysts appended with Fluoride Substituents; probing catalytic performance via a combined experimental and MLR study

2021 ◽  
Author(s):  
Qiuyue Zhang ◽  
Wenhong Yang ◽  
Zheng Wang ◽  
Gregory A. Solan ◽  
Tongling Liang ◽  
...  
Keyword(s):  
Ethylene Polymerization ◽  
Catalytic Performance ◽  
Chloride Complex ◽  
Polymerization Catalysts

Access to six examples of α,α’-bis(imino)-2,3:5,6-bis(pentamethylene)pyridine-iron(II) chloride complex, [2,3:5,6-{C4H8C(N(2-R1-4-R3-6-R2C6H2)}2C5HN] (R1 = Me, R2 = R3 = CH(p-FPh)2 Fe1; R1 = Et, R2 = R3 = CH(p-FPh)2 Fe2; R1 = iPr,...

3D-QSAR as a Tool for Understanding and Improving Single-Site Polymerization Catalysts. A Review

2014 ◽  
Vol 33 (12) ◽  
pp. 2944-2959 ◽  
Author(s):  
Victor L. Cruz ◽  
Sonia Martinez ◽  
Javier Ramos ◽  
Javier Martinez-Salazar
Keyword(s):  
3D Qsar ◽  
Single Site ◽  
Polymerization Catalysts
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