Group 3 metal catalysts for ethylene and α-olefin polymerization (original) (raw)
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From Unstable to Stable: Half-Metallocene Catalysts for Olefin Polymerization †
Inorganic Chemistry, 2008
The reaction of LAlMeOH [L) CH(N(Ar)(CMe)) 2 , Ar) 2,6-i-Pr 2 C 6 H 3 ] with CpTiMe 3 , Cp*TiMe 3 , and Cp*ZrMe 3 was investigated to yield LAlMe(µ-O)TiMe 2 Cp (2), LAlMe(µ-O)TiMe 2 Cp* (3), and LAlMe(µ-O)ZrMe 2 Cp* (4), respectively. The resulting compounds 2-4 are stable at elevated temperatures, in contrast to their precursors such as CpTiMe 3 and Cp*ZrMe 3 , which already decompose below room temperature. Compounds 2-4 were characterized by singlecrystal X-ray structural analysis. Compounds 2 and 3 were tested for ethylene polymerization in the presence of methylaluminoxane. The half-metallocene complex 3 has higher activity compared to 2. The polydispersities are in the range from 2.8 to 4.2. A copolymerization with styrene was not observed.
Journal of the American Chemical Society, 1995
This contribution reports the synthesis and activity as precatalysts for stereoselective propylene polymerization of several chiral non-C2 symmetric zirconocene and hafnocene complexes, (R)and (S)-Me2Si(Me&s)-(C5H3R*)MR2 (R = Cl(2) or Me(3)) where R* = (1R,2S,5R)-trans-5-methyl-cis-2-(2-propyl)cyclohexyl ((-)-menthyl; M = Zr, (a) and M = Hf, (b)) and (1S,2S,5R)-truns-5-methyl-cis-2-(2-propyl)cyclohexyl ((+)-neomenthyl; M = Zr (c)). Metallocene dichlorides were prepared from MC4 and Li*MezSi(Me&)(CsH3R*) and converted to the corresponding dimethyl complexes with MeLimLiBr. All complexes were characterized by standard techniques, with absolute configuration established by circular dichroism and X-ray diffraction. For the (R)-R* = (-)menthyldichloro complex (2a): space group = P212121; a = 9.404(2), b = 9.817(3), c = 28.684(7) A(-120 "C), Z = 4; R(F) = 0.056, R,(F) = 0.061 for 2025 reflections having I > 3a(I). For the (R)-R* = (-)-menthyldimethyl complex (3a): space group = P~I ; a = 9.501(3), b = 9.394(3), c = 15.565(3) A, B = 103.76(2)"(-120 "C), Z = 2; R(F) = 0.037, R,(F) = 0.039 for 1528 reflections having I > 3a(I). Reaction of either (R)-3a or (R)-3b with B(C&)3 in toluene yields two spectroscopically discernible methyl cations. The temperature dependence of the ion-pair equilibrium constant in toluene yields AB =-0.7(1) kcal/mol and AS =-3.1(1) eu for (R)-3a and AH = 0.14(3) kcal/mol and AS =-3.1(1) for (R)-3b. "Cationic" propylene polymerization catalysts were generated from 2 + methylalumoxane or 3 + methylalumoxane, B(C&)3, Ph3C+B(C&)4-, or HN("Bu~)+B(C&)~-. Polymerization activities, stereoregularities, and polymer molecular weights are strongly dependent on cocatalyst identities and concentrations, suggesting strong, structure-sensitive ion-pairing effects. Polypropylene isotacticities as high as 95% mm" pentad content are observed, with stereoregularity increasing and polymerization activity falling with decreasing reaction temperature.
Catalysts for olefins polymerization
Catalysis Today, 1998
Polyole®ns are still protagonist of an exciting innovation, due to a continuous development of new catalysts, processes and products. The positive solutions given by polyole®ns to the environmental and energetic issues are among the factors responsible for their success. The most relevant breakthrough occurred in the last years is the discovery of metallocenes, and more in general, of single centre catalysts. They are, in most cases, highly active catalysts and are already employed on the industrial scale for the preparation of both``drop-in'' products with improved properties, and of totally new materials. # 1998 Elsevier Science B.V. All rights reserved.
Advances in Non-Metallocene Olefin Polymerization Catalysis
Chemical Reviews, 2003
I. Introduction and Development of the Field 283 II. Scope of Review 284 III. Group 3 Catalysts 286 IV. Group 4 Catalysts 286 A. Cp and Other Carbon-Donor Ligands 286 1. Cp-Based Precatalysts with an Additional Neutral Donor 286 2. Cp-Based Precatalysts with an Additional Anionic Donor 286 3. Metallocene-Related Precatalysts 288 4. Non-Cp Carbon-Based Ligands 289 B. Chelating Amides and Related Ligands 289 1. Diamide Ligands 289 2. Diamide Ligands with an Additional Donor 290 3.-Diketiminates and Related Six-Membered Chelate Ligands 291 4. Iminopyrrolides and Related Five-Membered Chelate Ligands 291 5. Amidinates and Related Four-Membered Chelate Ligands 292 6. Amide Ligands Forming Three-Membered Chelates 293 C. Chelating Alkoxides, Aryloxides, and Related Ligands 293 1. Salicylaldiminato Ligands 293 2. Bis(phenoxy) Amine Ligands 294 3. Other Aryloxide, Alkoxide, and Thiolate Ligands 294 4. Aryloxide and Alkoxide Ligands in Combination with Cp 294 V. Group 5 Catalysts 295 A. Precatalysts in the +V Oxidation State 295 B. Precatalysts in the +IV Oxidation State 296 C. Precatalysts in the +III Oxidation State 296 VI. Group 6 Catalysts 297 A. Cp-Based Ligands 297 B. Non-Cp-Based Amide, Amine, and Phenoxy Ligands 298 VII. Group 7 Catalysts 300 VIII. Group 8 Catalysts 300 A. Neutral Bis(imino)pyridine and Related Ligands 300 B. Anionic Ligands 302 IX. Group 9 Catalysts 302 X. Group 10 Catalysts 303 A. Neutral Ligands 303 1. R-Diimine and Related Ligands 303 2. Other Neutral Nitrogen-Based Ligands 304 3. Chelating Phosphorus-Based Ligands 304 B. Monoanionic Ligands 305 1. [PO] Chelates 305 2. [NO] Chelates 306 3. Other Monoanionic Ligands 306 4. Carbon-Based Ligands 306 XI. Group 11 Catalysts 307 XII. Group 12 Catalysts 307 XIII. Group 13 Catalysts 307 XIV. Summary and Outlook 308 XV. Glossary 308 XVI. References 308
Handbook of Transition Metal Polymerization Catalysts
Journal of the American Chemical Society, 2010
Over the last 60 years the ability to reduce olefi n refi nery gases or liquids to metastable plastics in a controlled manner has created the colossal polyolefi n materials business. In 2008 an estimated 120 million tonnes of polyolefi ns will be produced. 1 If one considers that the world population was estimated at 6.7 billion people in March 2008, 2 then each person consumed ∼ 18 kg of polyolefi n this year. While this is a considerable per-capita consumption, it should be noted that polyolefi ns afford major environmental benefi ts in such areas as infrastructure (piping and energy transmission), allowing the safe and consistent supply of water and energy (electricity and gas etc) and the removal of sewage; advanced packaging: light and reliable packaging that increases the shelf-life of perishable goods and thus decreases petroleum fuel consumption for shipment because of less weight and less spoilage; automotive applications: and replacing metal with light material producing lighter automobiles and again further contributing to reduced transport emissions. Finally, polyolefi ns themselves are in effect a source of energy. 3 This immense business has been brought about by catalysts and processes which control how macromolecules are assembled. By sequentially linking α-olefi ns, the chain length, skew, and branching present handles which tune properties. When the monomer is substituted (i.e., an α-olefi n), additional opportunities including tacticity (control over regio-error-type linkages) and
Group 4 transition metal complex cations for olefin polymerization
Die Makromolekulare …, 1991
Organometallic compounds of group 4 metals, such as Cp,Zr(CH,), , Cp,Ti(CH3), , CpZrBz, , TiBz,, ZrBz, (Cp = cyclopentadienyl, Bz = benzyl), when used alone have a negligible, if any, activity in promoting olefin polymerization I). However, as reported in the literature2s3) they become very active in promoting ethylene polymerization when combined with a large amount of methylaluminoxane (MAO).
A few considerations on some catalysts for olefin polymerization
Makromolekulare Chemie. Macromolecular Symposia, 1993
Among many precursors and catalysts for alpha‐olefins polymerization, one seems to be particularly interesting, because it has not been completely clarified yet.We refer especially to precursors obtained via reaction between Mg‐alkyls and SiCl4.The products of this reaction are not well known; in fact, under some operating conditions, a special form of MgCl2 is obtained, showing x‐ray diffraction peaks in the angular region lower than 15° (2 theta), which corresponds to the 5.9 A interplanar spacing, characteristic of alpha‐MgCl2.Under other conditions, MgCl2 is obtained in the well known and strongly disordered delta structure.By employing these precursors, some catalytic systems for alpha‐olefins polymerization have been prepared.In this paper, the peculiar aspects of these precursors and catalysts are described, particularly focusing on the correlation between structure and performances in ethylene and propylene polymerization.
Paradox of Late Transition-Metal Catalysts in Ethylene Polymerization
General Chemistry
Polyolefin materials are the most synthesized polymer used nowadays and symbolize the development level of the national petrochemical industry, in which polyethylenes are major along with alternative product α-olefins for co-monomer and substrates for fine chemicals. Likely operating catalysts such as Ziegler-Natta and metallocene meet all demanding of various polyethylene materials, what is any business in developing late-transition metal catalysts for ethylene reactivity? In the past two decades, we realized the advantages of late-transition metal catalysts, such as easy variousness and easy preparation, good stability and high catalytic activity. Besides these, the characteristic different polyethylenes have been achieved as either highly linear polyethylene or highly branched polyethylenes. Therefore, there are some spaces in developing new catalytic system on the base of late-transition metal catalysts to compromise the demanding for new polyethylenes from sole ethylene polymerization.
Polym. Chem., 2015
ABSTRACT The synthesis of four new group 4 metal complexes 1-4 (1 = (t-BuOS)2TiCl2; 2 = (CumOS)2TiCl2; 3 = (t-BuOS)2Zr(CH2Ph)2; 4 = (CumOS)2Zr(CH2Ph)2) bearing two bidentate thioetherphenolate ligands (t-BuOS-H = 4,6-di-tert-butyl-2-phenylsulfanylphenol; CumOS-H = 4,6-bis-(α,α-dimethylbenzyl)-2- phenylsulfanyl phenol) has been accomplished. These complexes show a fluxional solution behaviour revealed by VT 1H NMR and supported by density functional theory (DFT) calculations. All complexes are active catalyst in ethylene polymerization producing linear polyethylene. Notably the zirconium complex 3 displays under proper reaction conditions a very high activity (1422 kgPE•molcat-1•bar-1•h-1) that well compares with that of the most active post-metallocene catalysts. Furthermore propylene polymerization catalyzed by the titanium complex 1 yields atactic polypropylene whereas the zirconium complexes 3 and 4 selectively produces oligopropylene with Schultz-Flory distribution. The NMR analysis of the unsaturated chain-endings in the latter samples evidenced regioselective propagation reaction with a large preference for the 1,2- monomer insertion. DFT calculations allowed modelling the elementary reaction steps, namely the chain propagation reaction, β-hydrogen elimination and transfer, highlighting the importance of the flexibility and the steric hindrance of the ancillary ligands to determinate the high activity of the title catalysts.