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.

Design of vanadium complex catalysts for precise olefin polymerization.

Recent examples for synthesis of group 4 transition metal (Ti, Zr, Hf) complexes, especially nonbridged half-metallocenes containing anionic donor ligands of the type, Cp′MX 2 (L) (Cp′ = cyclopentadienyl group; M = Ti, Zr, Hf; X = halogen, alkyl etc.; L = anionic donor ligands), as catalysts for precise olefin polymerization have been reviewed. It has been revealed that these complex catalysts displayed unique characteristics especially for ethylene copolymerizations and some examples are known to produce new polyolefins that cannot be prepared by ordinary catalysts such as classical Ziegler–Natta, metallocenes. Modification of both cyclopentadienyl fragment and anionic ancillary donor ligands are the key for precise olefin (co)polymerization.

Nonbridged half-metallocenes containing anionic ancillary donor ligands: New promising candidates as catalysts for precise olefin polymerization

Olefiin polymerization behavior of phenoxy-based catalysts has been discussed. Phenoxy-based olefin polymerization catalysts are capable of showing high catalytic activities. Moreover, the phenoxy-based catalysts can display unique catalytic properties and thus have offered opportunities to make polyolefinic materials that are difficult or impossible to prepare using conventional catalysts. Therefore, the phenoxy-based catalysts have opened up a new dimension in the fields of olefin polymerization catalysis and polymer synthesis.

Recent Advances in Phenoxy-Based Catalysts for Olefin Polymerization

Synthesis, structures, and catalytic reactions of ring-substituted titanium(IV) complexes.

Effect of the Cyclopentadienyl Fragment on Monomer Reactivities and Monomer Sequence Distributions in Ethylene/α-Olefin Copolymerization by a Nonbridged (Cyclopentadienyl)(aryloxy)titanium(IV) Complex−MAO Catalyst System

Effect of ligand in copolymerization of ethylene with 1-hexene by (cyclopentadienyl)(aryloxy)titanium(IV) complexes of the type, Cp′TiCl2(OAr) [OAr=O-2,6-iPr2C6H3 and Cp′=C5Me5 (1), 1,3-tBu2C5H3 (2), tBu2C5H4 (3), 1,3-Me2C5H3 (5), Cp (6); OAr=O-2,6-Me2C6H3 and Cp′=C5Me5 (7), 1,3-tBu2C5H3 (8)], has been explored in the presence of MAO, and [Me2Si(C5Me4)(NtBu)]TiCl2 (4) was chosen as the reference. It was revealed that 1 exhibited the highest catalytic activity, and the resultant poly(ethylene-co-1-hexene)s possessed relatively high molecular weights with narrow molecular weight distributions ( M w =29.5×10 4 to 34.5×10 4 ,M w /M n =1.74 –1.88), and contained 1-hexene in relatively high extents (36.6–43.5 mol%). Effect of both cyclopentadienyl and aryloxy groups plays an essential key role in the copolymerization not only to exhibit high catalytic activity but also to afford relatively high molecular weight copolymer with narrow polydispersity. It also turned out that α-olefin incorporation into the copolymer is highly affected by the substituents on the cyclopentadienyl group. The monomer reactivity ratios were not affected by both the polymerization temperature and Al/Ti molar ratios, but the monomer sequence distributions and the monomer reactivity ratios depended upon cyclopentadienyl fragment used. In spite of the rather wide bond angle of Cp–Ti–O (ca. 120.5°) in 1–3 than that of Cp–Ti–N in 4 (107.6°), a high level of 1-hexene incorporation and smaller rErH value by 1–3 than those by 4 were attained, which would be due to the flexible internal rotation of both cyclopentadienyl and aryloxy groups.

Keima Oya

Papers

Effect of the Cyclopentadienyl Fragment on Monomer Reactivities and Monomer Sequence Distributions in Ethylene/α-Olefin Copolymerization by a Nonbridged (Cyclopentadienyl)(aryloxy)titanium(IV) Complex−MAO Catalyst System

Ethylene/α-olefin copolymerization by various nonbridged (cyclopentadienyl)(aryloxy)titanium(IV) complexes — MAO catalyst system