Scandium complex [{(.eta.5-C5Me4)Me2Si(.eta.1-NCMe3)}(PMe3)ScH]2: a unique example of a single-component .alpha.-olefin polymerization catalyst

Shapiro, Pamela J.; Bunel, Emilio E.; Schaefer, William P.; Bercaw, John E.

doi:10.1021/om00117a055

Cited by 547 publications

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“…The ansa-monocyclopentadienylamido ligand for olefin polymerization catalyst was originally introduced by Bercaw and colleagues 10 in a scandium complex, and the titanium complex with ansa-monocyclopentadienylamido ligand was first reported by Okuda 11 The commercial application of group IV ansa-monocyclopentadienylamido complexes was developed by Dow and Exxon and was named constrained geometry catalysts (CGCs) after the structure of the complexes. CGCs are superior in the copolymerization of ethene with 1-alkene or styrene compared with bis(cyclopentadienyl) group IV metal complexes and have been applied for the production of ethene-based copolymers such as linear low-density polyethylene.…”

Section: Synthesis and Structures Of Titanium Complexes Synthesis Of mentioning

confidence: 99%

Living polymerization of olefins with ansa-dimethylsilylene(fluorenyl)(amido)dimethyltitanium-based catalysts

Shiono

2011

Polym J

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This article reviews the living homopolymerization and copolymerization of propene, 1-alkene and norbornene with ansadimethysilylene(fluorenyl)(amido)dimethyltitanium, Me 2 Si(g 3 -C 13 H 8 )(g 1 -N t Bu)TiMe 2 and its derivatives, correlating the effects of cocatalysts, solvents, polymerization conditions and the substituents of the fluorenyl ligand with catalytic features, such as livingness, initiation efficiency, propagation rate, syndiospecificity and copolymerization ability. The synthesis of novel olefin block copolymers and their catalytic synthesis are also introduced using this living system. Polymer Journal (2011) 43, 331-351; doi:10.1038/pj.2011 Keywords: cycloolefin copolymer; living polymerization; norbornene; propene; single-site catalyst; syndiospecific polymerization; 1-alkene A living polymerization system, in which neither chain transfer nor deactivation occurs, affords polymers with predictable molecular weights and narrow molecular weight distributions (MWDs). Living polymerization techniques are utilized for the synthesis of terminally functionalized polymers and block copolymers. Another feature of living polymerization is its simple kinetics. Because neither chain transfer nor deactivation occurs in living polymerization, the number of polymer chains (N) is equal to the number of active centers ([C*]), and the number-average molecular weight (M n ) directly reflects the propagation rate. In living polymerization, the propagation rate can be evaluated from the M n value and the polymerization time. As chain transfer via b-elimination and/or transmetalation with trialkylaluminum as a cocatalyst is inevitable in conventional Ziegler-Natta catalytic systems; homogeneous V(acac) 3 /Et 2 AlCl (where acac is acetylacetonate or its analog) had previously been the only catalytic system that produced syndiotactic-rich living polypropylene (PP) atThe development of metallocene catalysts has enabled us to produce a variety of uniform olefin copolymers and to control the stereoregularity of poly(1-alkene)s. 3,4 The success of metallocene catalysts has stimulated research on transition metal complexes for olefin polymerization, 5-7 so-called single-site catalysts, which has also resulted in various transition metal complexes for the living polymerization of olefins. 8,9 We have also developed a living polymerization system using ansa-dimethysilylene(fluorenyl)(amido)dimethyltitanium, Me 2 Si(Z 3 -C 13 H 8 )(Z 1 -N t Bu)TiMe 2 (1), combined with a suitable cocatalyst. The catalytic system allows not only a syndiospecific living polymerization of propene and a 1-alkene but also a living homopolymerization and copolymerization of norbornene with a 1-alkene. We investigated the effect of cocatalyst, solvent and the ligand of the titanium complex on propene polymerization in terms of the livingness of the system. We also synthesized novel olefin block copolymers with the living system. This article reviews the characteristics of 1-based catalysts for tailor-made polyolefins. SYNTHESIS AND STRUCTURES OF TIT...

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Section: Synthesis and Structures Of Titanium Complexes Synthesis Of mentioning

confidence: 99%

Living polymerization of olefins with ansa-dimethylsilylene(fluorenyl)(amido)dimethyltitanium-based catalysts

Shiono

2011

Polym J

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“…Since these are well defined, single-component catalyst systems, an investigation of their reactions with a-olefins provides a rare opportunity to probe the mechanisms of chain propagation and chain termination in Ziegler-Natta polymerization. The tertiary phosphine adducts [(r/5-CsMea)2SiMe2]ScH(PMe3) Piers, Shapiro, Bunel & Bercaw, 1990) and {[(r/5-C5 -Me4)SiMe2(r/~-NCMe3)](PMe3)Sc}2(/z-H)2 (Shapiro, Bunel, Schaefer & Bercaw, 1990) are effective catalysts; however, the role of the phosphine in stabilizing their structures and/or inhibiting olefin insertion is not yet clear. The title compound, with a tertiary phosphine ligand linked to a cyclopentadienyl group, was prepared to examine the reactivity of a scandium alkyl with a high effective [PR3] concentration.…”

Section: Introduction Organoscandium Derivatives May Servementioning

confidence: 99%

Structure of a scandium-(silicon-bridged Cp, Cp*) complex

Schaefer¹,

Köhn²,

Bercaw³

1992

Acta Crystallogr C

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“…1990 年 Bercaw 等设计合成了含硅桥联氮负离子侧链的四甲基环戊二烯配体, 并得到了限定几何构型的单茂钪配合物(图 12) [127,128] . 含硅桥联氮负离子侧链的四甲基环戊二烯基是一种 8 电子给体, 与中心金属离子以 [129] .…”

Section: 单茂稀土金属有机配合物unclassified

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

Changtao¹,

Wang²,

Chen³

2014

Acta Chim. Sinica

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Rare-earth elements include scandium, yttrium and fifteen lanthanides. Since Wilkinson and Birmingham reported the fist example of rare-earth organometallic complex, the chemistry of rare-earth organometallic complexes has had a great advance during the past sixty years. A variety of Cp containing rare-earth metal complexes, including mono-Cp, bis-Cp, and tri-Cp complexes, have been synthesized. Variation of the size of substituent on Cp ring, introducing the nitrogen or oxygen containing pendant arm to Cp ring or using ansa bis-Cp ligands make the synthesis and stabilization of these three types of rare-earth metal Cp complexes available. The Cp related ligands, such as indenyl and fluorenyl, also have been applied for the rare-earth organometallic complexes. From 1990's, there was a tendency to explore the rare-earth organometallic complexes with ancillary ligands beyond Cp and its derivatives in order to search for more efficient rare-earth metal catalysts. Non-Cp ligands, such as biphenolates, β-diketiminates, amidinates, guanidinates, etc. have been introduced into the chemistry of rare-earth organometallic complexes, and a larger number of non-Cp rare-earth organometallic complexes have been synthesized and characterized. The application of non-cyclopentadienyl ligands not only resulted in the rare-earth organometallic complexes with new structural features, but also the catalysts with high activity and high selectivity for the polymer synthesis and organic synthesis. The rare-earth organometallic complexes catalyze homo-and co-polymerization of olefins as well as specific polymerization of dienes and polar monomers. The discovery of the catalytic system composed of the neutral rare-earth metal dialkyls/borate enables to synthesize some interesting polymers which are difficult to be prepared by using other catalytic system. The rare-earth organometallic complexes are also able to catalyze some important organic reactions, such as hydroamination, hydrophosphinylation, and hydroalkoxylation, etc. Different from the late-translation metal catalyzed organic reactions, most of the rare-earth metal catalyzed ones do not involve oxidative addition and reductive elimination steps. The review describes some important developments of the chemistry of rare-earth organometallic complexes in the past sixty years.

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Scandium complex [{(.eta.5-C5Me4)Me2Si(.eta.1-NCMe3)}(PMe3)ScH]2: a unique example of a single-component .alpha.-olefin polymerization catalyst

Cited by 547 publications

References 0 publications

Living polymerization of olefins with ansa-dimethylsilylene(fluorenyl)(amido)dimethyltitanium-based catalysts

Living polymerization of olefins with ansa-dimethylsilylene(fluorenyl)(amido)dimethyltitanium-based catalysts

Structure of a scandium-(silicon-bridged Cp, Cp*) complex

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

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