Late-metal catalysts for ethylene homo- and copolymerization.

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

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Advances in non-metallocene olefin polymerization catalysis.

One of the most exciting developments in the areas of catalysis, organometallic chemistry, and polymer science in recent years has been the intense exploration and commercialization of new polymerization technologies based on single-site and metallocene coordination olefin polymerization catalysts.1 The vast number of specifically designed/synthesized transition metal complexes (catalyst precursors) and main-group organometallic compounds (cocatalysts) allows unprecedented control over polymer microstructure, the generation of new polymer architectures, and the development of new polymerization reactions. Commercialization of new generations of single-site and metallocene catalyst-based technologies has provided the multibillion pound per year polyolefins industry with the ability to deliver a wide range of new and innovative olefin-based polymers having improved properties.2-4 The intense industrial activity in the field and the challenges to our basic understanding that have come to light have in turn 1391 Chem. Rev. 2000, 100, 1391−1434

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Cocatalysts for Metal-Catalyzed Olefin Polymerization: Activators, Activation Processes, and Structure−Activity Relationships

Highly Active Iron and Cobalt Catalysts for the Polymerization of Ethylene

Selectivity in propene polymerization with metallocene catalysts.

Living Polymerization of α-Olefins Using NiII−α-Diimine Catalysts. Synthesis of New Block Polymers Based on α-Olefins

Mechanistic studies of olefin polymerizations catalyzed by aryl-substituted α-diimine−Pd(II) complexes are presented. Syntheses of several cationic catalyst precursors, [(N∧N)Pd(CH3)(OEt2)]BAr‘4 (N∧N = aryl-substituted α-diimine, Ar‘ = 3,5-(CF3)2C6H3), are described. X-ray structural analyses of [ArNC(H)C(H)NAr]Pd(CH3)(Cl) and [ArNC(Me)C(Me)NAr]Pd(CH3)2 (Ar = 2,6-(iPr)2C6H3) illustrate that o-aryl substituents crowd axial sites in these square planar complexes. Low-temperature NMR studies show that the alkyl olefin complexes, (N∧N)Pd(R)(olefin)+, are the catalyst resting states and that the barriers to migratory insertions lie in the range 17−19 kcal/mol. Following migratory insertion, the cationic palladium alkyl complexes (N∧N)Pd(alkyl)+ formed are β-agostic species which exhibit facile metal migration along the chain (“chain walking”) via β-hydride elimination/readdition reactions. Model studies using palladium−n-propyl and −isopropyl systems provide mechanistic details of this process, which is respon...

Mechanistic Studies of Pd(II)−α-Diimine-Catalyzed Olefin Polymerizations1

A series of stable dialkyl complexes of Pd, (α-diimine)PdR2 (α-diimine = aryl-substituted diimine, R = n-Pr, n-Bu, i-Bu), have been prepared via Grignard alkylation of the corresponding (α-diimine)PdCl2 complexes Protonation of these dialkyl species at low temperature results in loss of alkane and formation of cationic Pd β-agostic alkyl complexes, which have been observed as intermediates in the polymerization of ethylene and propylene by these Pd catalysts Studies of the structure and dynamic behavior of these alkyl complexes are presented, along with the results of trapping reactions of these species with ligands such as NCMe, CO, and C2H4 Trapping with ethylene results in formation of cationic alkyl ethylene complexes which model the catalyst resting state in these systems These complexes have been used to obtain mechanistic details and kinetic parameters of several processes, including isomerization of the alkyl ethylene complexes, associative and dissociative exchange with free ethylene, and mig

Palladium(II) β-Agostic Alkyl Cations and Alkyl Ethylene Complexes: Investigation of Polymer Chain Isomerization Mechanisms

α-Diimine complexes of palladium and nickel catalyze the polymerization of α-olefins to give new materials that range from low-Tg elastomers to low-melting, partially crystalline polymers. The 1H a...

13C NMR Analysis of α-Olefin Enchainment in Poly(α-olefins) Produced with Nickel and Palladium α-Diimine Catalysts

The Dynamics of the β-Agostic Isopropyl Complex (ArNC(R)−C(R)NAr)Pd(CH(CH2-μ-H)(CH3))+BAr4‘- (Ar = 2,6-C6H3(i-Pr)2): Evidence for In-Place Rotation versus Dissociation of the Agostic Methyl Group

Daniel Joseph Tempel

Papers

Living Polymerization of α-Olefins Using NiII−α-Diimine Catalysts. Synthesis of New Block Polymers Based on α-Olefins

Mechanistic Studies of Pd(II)−α-Diimine-Catalyzed Olefin Polymerizations1

Palladium(II) β-Agostic Alkyl Cations and Alkyl Ethylene Complexes: Investigation of Polymer Chain Isomerization Mechanisms

13C NMR Analysis of α-Olefin Enchainment in Poly(α-olefins) Produced with Nickel and Palladium α-Diimine Catalysts

The Dynamics of the β-Agostic Isopropyl Complex (ArNC(R)−C(R)NAr)Pd(CH(CH2-μ-H)(CH3))+BAr4‘- (Ar = 2,6-C6H3(i-Pr)2): Evidence for In-Place Rotation versus Dissociation of the Agostic Methyl Group