Polymerization Of Α-olefins Research Articles

Living Polymerization of α-Olefins at Elevated Temperatures Catalyzed by a Highly Active and Robust Cyclophane-Based Nickel Catalyst

ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTLiving Polymerization of α-Olefins at Elevated Temperatures Catalyzed by a Highly Active and Robust Cyclophane-Based Nickel CatalystDrexel H. Camacho and Zhibin GuanView Author Information Department of Chemistry, University of California, Irvine, California 92697-2025 Cite this: Macromolecules 2005, 38, 7, 2544–2546Publication Date (Web):March 1, 2005Publication History Received7 January 2005Revised12 February 2005Published online1 March 2005Published inissue 1 April 2005https://doi.org/10.1021/ma050039uCopyright © 2005 American Chemical SocietyRIGHTS & PERMISSIONSArticle Views1247Altmetric-Citations124LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit Read OnlinePDF (85 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information SUBJECTS:Alkyls,Catalysts,Hydrocarbons,Living polymerization,Olefin polymerization Get e-Alerts

Highly active new α-diimine nickel catalyst for the polymerization of α-olefins

A new silylated α-diimine ligand, bis[ N, N′-(4- tert-butyl-diphenylsilyl-2,6-diisopropylphenyl)imino]acenaphthene 3, and its corresponding Ni(II) complex, {bis[ N, N′-(4- tert-butyl-diphenylsilyl-2,6-diisopropylphenyl)imino]acenaphthene}dibromonickel 4, have been synthesized and characterized. The crystal structures of 3 and 4 were determined by X-ray crystallography. In the solid state, complex 4 is a dimer with two bridging Br ligands linking the two nickel centers, which have square pyramidal geometries. Complex 4, activated either by diethylaluminum chloride (DEAC) or methylaluminoxane (MAO) produces very active catalyst systems for the polymerization of ethylene and moderately active for the polymerization of propylene. The activity values are in the order of magnitude of 10 7 g PE (mol Ni [E] h) −1 for the polymerization of ethylene and of 10 5 g PP (mol Ni [P] h) −1 for the polymerization of propylene. NMR analysis shows that branched polyethylenes (PE) are obtained at room or higher temperatures and almost linear PE is obtained at 0 °C with 4/DEAC.

The first rare earth organometallic complex of 1,4,7-trithiacyclononane: a precursor to unique cationic ethylene and α-olefin polymerisation catalysts supported by an all-sulfur donor ligand

[Sc([9]aneS3)(CH2SiMe3)3], the first rare earth organometallic complex of 1,4,7-trithiacyclonane, is a precursor to ethylene and alpha-olefin polymerisation catalysts upon activation with BAr(F)3 or [CPh3][BAr(F)4](Ar(F) = C6F5); these are the first cationic rare earth organometallic catalysts supported by an all-sulfur donor ligand.

Developments of rare earth metal catalysts for olefin polymerization

This review article describes recent developments in rare earth metal complexes as polymerization catalysts, focusing on the polymerization of ethylene and α-olefins. Most of this kind of catalysts had been based on metallocene type complexes, and their catalytic behaviors are surveyed. Advanced series of half-metallocene and non-Cp type catalyst systems are also summarized.

Zirconocene catalyst well spaced inside modified montmorillonite for ethylene polymerization: role of pretreatment and modification of montmorillonite in tailoring polymer properties

Zirconocene catalyst was heterogenized inside an organosilane-modified montmorillonite (MMT) pretreated by calcination and acidization, for supported catalyst systems with well-spaced α-olefin polymerization active centers. The varied pretreatment and modification conditions of montmorillonite are efficient for supported zirconocene catalysts in control of polyethylene microstructures, in particular, molecular weight distribution. In contrast to other supported catalyst systems, Cp 2ZrCl 2/modified montmorillonite(MMT-7)-supported catalysts with a distinct interlayer structure catalyzed ethylene homopolymerization and copolymerization with 1-octene activated by methylaluminoxane (MAO), resulting in polymers with a bimodal molecular weight distribution (MWD).

Is the Polymerization of Linear α-Olefins by Transition-Metal Carbene Complexes a Viable Process? A Theoretical Study Based on Density Functional Theory

Gradient-corrected density functional theory has been used to study the mechanism of α-olefin polymerization catalyzed by transition-metal carbene complexes. Taking the [CH2Re(NO)2(PMe3)]+ complex as an example, we investigated the possible elementary steps of the polyethylene formation. This “carbene-to-metallacycle” style mechanism based on a pure carbene intermediate starts with the coordination of the ethylene. Then ethylene reacts with the carbene complex by a [2 + 2] addition. Metallacyclobutane decomposition to a new carbene complex takes place by an α-hydrogen transfer reaction. We have also investigated the possible side reactions for the metallacyclobutane decomposition by metathesis reaction, cyclization, and β-hydride transfer reactions. Calculations have been performed on the monomer and carbene complexes, on the possible intermediates, ethylene π-complexes, metallacyclobutanes, cyclopropyl complexes, cyclopropyl hydride complexes, propylidene complexes, propene π-complexes, allyl−hydride int...

Synthesis and characterization of cationic and zwitterionic allyl zirconium complexes derived from trimethylenemethane (TMM) cyclopentadienylzirconium acetamidinates

Protonation of the trimethylenemethane derivatives, Cp*Zr(σ 2,π-C 4H 6)[N(R 1)C(Me)N(R 2)] ( 1a: R 1=R 2= i-Pr and 1b: R 1=Et, R 2= t-Bu) (Cp*=η 5-C 5Me 5), by [PhNMe 2H][B(C 6F 5) 4] in chlorobenzene at −10 °C provides the cationic methallyl complexes, Cp*Zr(η 3-C 4H 7)[N(R 1)C(Me)N(R 2)] ( 2a: R 1=R 2= i-Pr and 2b: R 1=Et, R 2= t-Bu), which are thermally robust in solution at elevated temperatures as determined by 1H NMR spectroscopy. Addition of B(C 6F 5) 3 to 1a and 1b provides the zwitterionic allyl complexes, Cp*Zr{η 3-CH 2C[CH 2B(C 6F 5) 3]CH 2}[N(R 1)C(Me)N(R 2)] ( 3a: R 1=R 2= i-Pr and 3b: R 1=Et, R 2= t-Bu). The crystal structures of 2b and 3a have been determined. Neither the cationic complexes 2 or the zwitterionic complexes 3 are active initiators for the Ziegler-Natta polymerization of ethylene and α-olefins.

Monocyclopentadienyl and ansa-Monocyclopentadienylalkoxo Complexes of Titanium Containing the 2,2‘-Methylenebis(6-tert-butyl-4-methylphenoxo) Ligand. Synthesis, Characterization, and Polymerization Catalyst Behavior. Molecular Structure of Ti(η5-C5H5)(η2-MBMP)Cl, Ti(η5-C5Me5)(η2-MBMP)Cl, and Ti(η5-C5H4SiMe2-η1-MBMP)Cl2

The dialkoxo titanium complexes TiCp‘(η2-MBMP)Cl [Cp‘ = η5-C5H5 (1); η5-C5Me5 (2)] have been prepared in good yields by reaction of Li2(MBMP) with the corresponding monocyclopentadienyltrichloro titanium derivative. In a similar reaction the addition of 1 equiv of Li2(MBMP) to Ti(η5-C5H4SiMe2Cl)Cl3 generates the analogous titanium compound Ti(η5-C5H4SiMe2Cl)(η2-MBMP)Cl (3), while the ansa-cyclopentadienylalkoxo complex Ti(η5-C5H4SiMe2-η1-MBMP)Cl2 (4) is formed when MBMPH2 is treated with Ti(η5-C5H4SiMe2Cl)Cl3 in the presence of NEt3 in 1:1:2 molar ratio. Compounds 1, 2 and 4 have been characterized by single-crystal X-ray crystallography. DFT calculations were performed in order to elucidate the energies and geometries for these compounds. Upon addition of methylaluminoxane (MAO), the bisphenoxo complexes are active in the polymerization of α-olefins.

Higher α-Olefin Polymerization Behavior of a Bis(Phenoxy-Imine)Titanium Complex/i-Bu3Al/Ph3CB(C6F5)4 Catalyst System

Abstract Catalytic behavior of a bis(phenoxy-imine)Ti complex/i-Bu3Al/Ph3CB(C6F5)4 catalyst system for higher α-olefin polymerization was investigated. The catalyst system exhibited higher activities towards α-olefins having larger molecular sizes and formed ultra-high molecular weight poly(higher α-olefin)s.

Novel 2-indenyl ansa-zirconocenes for the polymerization of α-olefins

A new synthetic route to C-2 bridged indenyl metallocenes utilizing the anion of 1-indanone has been developed. Two new ansa-zirconocene complexes 1a and 1b were synthesized and examined as precursors for the polymerization of α-olefins. These metallocenes were shown to be active for the polymerization of ethylene and for the oligiomerization of propylene when activated with excess methylaluminoxane (MAO).

Synthesis of novel metallacyclic zirconocene complexes from ω-alkenyl-functionalized zirconocene dichloride complexes and their use in the α-olefin polymerization

Novel metallacyclic zirconocene complexes were prepared by reacting ω-alkenyl substituted zirconocene dichloride complexes with two equivalents of n-butyllithium. The factor determining the reaction course and the structure of the respective metallacycle formed is the chain length of the alkenyl group. After activation with methylaluminoxane the metallocene dichloride complexes and the derived metallacyclic derivatives are excellently suited for ethylene polymerization.

Catalytic Copolymerization of Ethylene and Polar and Nonpolar α-Olefins in Emulsion

Novel P,O-chelated Ni(II) catalysts for ethylene and α-olefins polymerization have been used for the copolymerization of ethylene with various long-chain α-olefins in emulsion. Nonfunctionalized α-olefins have been copolymerized with ethylene using miniemulsion to disperse the catalyst at the nanometric level. The influence of the comonomer on catalyst performances as well as latex properties has been analyzed. High comonomer incorporation and stable latex of 30% solid content can be achieved by this method. Other comonomers such as α,ω-dienes, α-olefins bearing a polar functionality in the ω-position, and styrene have also been copolymerized in emulsion. Polymers and latexes have been characterized by an array of techniques including 13C NMR, TEM, DSC, and GPC. It is shown that this emulsion process is specially adapted for copolymerization of ethylene with polar olefins.

Synthesis and characterization of niobium(V) and tantalum(V) derivatives with diamido ligands. Molecular structure of {4,5-Me 2- o-C 6H 2(NSiMe 3) 2} 2NbCl and of a tantalum imide

The reactions between lithium bis(trimethyl)phenylenediamide and niobium or tantalum pentachlorides at low temperature afforded [{4,5-Me 2-C 6H 2(NSiMe 3) 2} 2MCl] (M=Nb ( 1), Ta ( 2)) independently of the stoichiometry used, 1:1 or 2:1. The reaction between tantalum pentachloride and N, N′-bis(trimethylsilyl)- o-dimethylphenylene diamide o-C 6H 2Me 2(NSiMe 3) 2 in Et 2O–DME at −78 °C leads to a tantalum(V) imide 3. Monosubstitution with diamides was achieved on tantalum with the more rigid 1,8-diamido-naphtalene. The various compounds were characterized by elemental analysis, FT-IR and NMR. Compounds 1 and 3 were characterized also by single crystal X-ray diffraction. The metal is pentacoordinated for 1 bearing two bidentate o-phenylenediamide ligands and a chlorine in the apical position of a distorted square-tetragonal pyramid. The salient features are a disymmetrical coordination mode of the diamide ligand with two quite different Nb–N distances namely 1.981(2) and 2.053(3) Å, as well as short Nb–C distances with the phenyl ring [2.495(3) and 2.471(3) Å]. The diamide ligand is thus coordinated in a η 4-fashion in the solid state. The salient feature of the structure of 3 is the presence in the metal coordination sphere of the functional imido ligand [Me 2C 6H 2N(SiMe 2Cl)(NSiMe 3− x Cl x )] 2− ( x=1 or 0) which was generated by N–Si bond cleavage and Si–Me/Si–Cl scrambling. Tantalum is six-coordinate, linked to the bulky imido ligand, three chlorine and a bidentate dimethoxyethane. The surrounding of the metal is distorted with a TaN bond distance of 1.706(5) Å and a large Ta–N(2)–C(2) angle [170.7(5)°]. The thermal behavior as well as the reactivity as soluble α-olefin polymerization catalyst were evaluated for 1.

Application of porous inorganic materials to adsorptive separation of methylalumoxane used as co-catalyst in olefin polymerization

Inorganic siliceous porous materials with different average pore diameters were applied to the adsorptive separation of methylalumoxane (MAO) used as co-catalyst in α-olefin polymerization. The co-catalytic performance of the separated MAO was investigated by propylene polymerization with rac-ethylene(bisindenyl)zirconium dichloride (rac-Et(Ind)2ZrCl2). The polymerization activity and the stereoregularity of the resulting polymer were markedly dependent upon the pore size of the porous material used for adsorptive separation. From the results obtained by the solvent extraction of the produced polymers, it was suggested that the adsorptive separation of MAO by porous materials is helpful in the characterization of MAO, and at least two different species of MAO are present.

Anion Exchange in Alkyl−Zirconocene Borate Ion Pairs. Are Solvated Alkyl−Zirconocene Cations Relevant Intermediates?

Ion pairs of the type Cpx2ZrMe+···A- containing various ansa-zirconocene methyl cations in contact with Me-B(C6F5)3- or B(C6F5)4- anions have been studied with regard to their anion exchange kinetics by 2D-NMR methods in benzene or toluene solutions. The resultsacceleration of anion exchange by added Li+···Me−B(C6F5)3-, substantial nonproductive exchange between added and Zr-bound Me-B(C6F5)3- anions, an increase of exchange rates at increased zirconocene concentrations, and the exclusively entropic origin of this rate increaseall indicate that anion exchange occurs by way of ion quadruples or higher ionic aggregates, rather than via dissociation to solvent-separated ions. These findings imply that solvent-separated (i.e. anion-free) alkyl zirconocene cations are unlikely to be relevant intermediates in reaction systems containing Cpx2ZrMe+···A- ion pairs and, hence, also in zirconocene-based catalyst systems for the polymerization of α-olefins.

Vanadium(III) and -(IV) Complexes withO,N-Chelating Aminophenolate Ligands: Synthesis, Characterization and Activity in Ethene/Propene Copolymerization

Monoanionic, potentially bi- or terdentate aminophenolates, ([OC6H3(CH2NMe2)-2-R-4)]−, R = H (a), Me (b), tBu (c), Cl (d), N=NPh (e), MeO (f) and [OC6H2(CH2NMe2)2-2,6-Me-4]− (g)), have been used in the synthesis of well-defined vanadium-based catalysts for the polymerization of α-olefins. The reaction of [Cp2V] with the parent phenol of g resulted in oxidation of the vanadium(II) nucleus to obtain the vanadium(III) (tris)phenolate [V(OC6H2(CH2NMe2)2-2,6-Me-4)3] (1). Vanadium(III) aminophenolates could not be obtained by reaction of [VCl3(THF)3] with the sodium phenolates because of incorporation of NaCl. However, use of the corresponding silyl ether Me3SiOC6H3(CH2NMe2)-2-Me-4 (2) resulted in the formation of the chlorovanadium (bis)phenolate [VCl(OC6H3(CH2NMe2)-2-Me-4)2] (3). Attempts to oxidize 3 to the corresponding dichlorovanadium(IV) (bis)phenolate were not successful. No reaction was observed with CuCl, AgCl and PbCl2. A dark blue compound 4 was obtained with CuCl2, which was tentatively assigned as a VIII/CuII dinuclear species. Treatment of the vanadium(IV) oxo (bis)phenolates 5a−5f with SOCl2 in benzene at room temperature or in toluene at reflux temperature resulted in the formation of dark blue compounds 6a−6f, whose stoichiometries indicated excess chloride. Only when 5a and 5d were reacted with SOCl2 at −70 °C could the desired dichlorovanadium (bis)phenolates [VCl2(OC6H4(CH2NMe2)-2)2] (7a) and [VCl2(OC6H3(CH2NMe2)-2-Cl-4)2] (7d) be obtained. X-ray crystal structure determination of 1 and 3 showed that both compounds have a trigonal bipyramidal geometry with two aminophenolate ligands bound in a bidentate η2-O,N fashion to the vanadium center in similar ways. The compounds 1, 3, 6 and 7 were tested for ethene/propene copolymerization.

Influences of methylaluminoxane separated by porous inorganic materials on the isospecific polymerization of propylene

Inorganic silicous porous materials such as MFI type zeolite, mesoporous silica MCM-41 and silica gel with different average pore diameters were applied to the adsorptive separation of methylaluminoxane (MAO) used as a cocatalyst in α-olefin polymerizations. The separated MAOs combined with rac-ethylene-(bisindenyl)zirconium dichloride (rac-Et(Ind) 2 ZrCl 2 ) were introduced to propylene polymerization, and their influences on the polymerization activity and stereoregularity of the resulting polymers were investigated. The polymerzation activity and isotactic [mmmm] pentad of the produced propylene were markedly dependent upon the pore size of the porous material used for adsorptive separation. From the results obtained from solvent extraction of the produced polymers, it was suggested that there are at least two kinds of active species with different stereospecificity in the rac-Et(Ind) 3 ZrCl 2 /MAO catalyst system.

New C1 Symmetric Ziegler−Natta Type Zirconocenes for the Production of Isotactic Polypropylene

As part of our continued investigation of the polymerization behavior of substituted asymmetric indenyl−fluorenyl metallocenes, three new zirconocenes bearing 2,4-disubstitution on the indenyl moiety have been synthesized and evaluated as α-olefin polymerization catalysts. For the new complex ethylene-1-(9-fluorenyl)-2-[1-(2-methyl-4-phenyl)indenyl]zirconium dichloride (11), highly isotactic polypropylene with [mmmm] = 91% and Mw 1.1 × 105 at Tp = 40 °C was produced in very high yield. The dimethylsilylene analogue (13) gave similar results in terms of stereoregularity with a 2-fold increase in Mw. In addition, dimethylsilylene(9-fluorenyl)[1-(2,4-dimethyl)indenyl]zirconium dichloride (12) was prepared and found to be an effective catalyst precursor, although the smaller methyl substituent at the 4-position resulted in polypropylenes of lower stereoregularity.

Addition of Lewis bases and acids. Effect on α-olefins polymerization with soluble metallocenes, 2 Propylene

Addition of Lewis bases and acids. Effect on α-olefins polymerization with soluble metallocenes, 2 Propylene

Addition of Lewis bases and acids. Effect on α-olefins polymerization with soluble metallocenes, 1 Ethylene

In this paper the soluble system rac-Etnd 2 -ZrCl 2 /methylaluminoxane (MAO) was studied in propylene polymerization with additives. Lewis acid and base such as AlCl 3 and ethyl benzoate (EB) were used to evaluate their effects on polymerization kinetics, catalyst activities and polymer properties. The results obtained show a trend to improve the performance when AlCl 3 is added. The activity is decreased with EB, but the effect it not as strong a for ethylene (see Part 1). To further elucidate some of the different aspects of metallocene activation and reactivation in the reaction media, several reactions were carried out using different preactivation steps, with and without AlCl 3 . The preactivations were carried out taking account of the different results obtained with both additives (AlCl 3 and EB). The pretreatment with EB was not considered because the activity is decreased in the polymerization. AlCl 3 improves the activity when it is present during the preactivation step, but the presence of EB in the reactor during the polymerization step has a poisoning effect. These results show the importance of the preactivation step carried out without olefin. The molecular weight of polypropylene obtained remains almost unchanged in all the evaluated conditions. A complete discussion of ethylene and propylene results is included, taking account of Part 1 and 2.