Ethylene polymerization of nickel catalysts with α-diimine ligands: factors controlling the structure of active species and polymer properties

Semikolenova, Nina V.; Bryliakov, Konstantin P.; Antonov, A. A.; Sun, Wen‐Hua; Talsi, Evgenii P.

doi:10.1039/c9dt01297d

Cited by 46 publications

(23 citation statements)

References 68 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The DIP ligand remains planar, with a negligible deviation [1.8(3)°] of the imine nitrogen atoms from the plane of the pyridine ring. The diisopropyl groups are nearly orthogonal to the plane of the ligand [89.1(3), 79.8(3)°] forming a steric pocket around the phosphorus centre, similar to what is observed with α‐diimine ligand‐metal complexes . A somewhat close H ··· H distance between the para ‐H on the pyridine ring and ortho ‐proton on the BPh 4 moiety mirrors the interaction in solution indicated by the shielded 1 H NMR spectrum.…”

Section: Resultsmentioning

confidence: 52%

Diiminepyridine‐Supported Phosphorus(I) and Phosphorus(III) Complexes: Synthesis, Characterization, and Electrochemistry

et al. 2020

View full text Add to dashboard Cite

Diiminepyridines (DIP) are popular redox “non‐innocent” ligands with widespread application in late, first‐row transition metal mediated catalysis and coordination chemistry. Here, we report the isolation and characterization of a pair of phosphorus coordination complexes in the +1 and +3 oxidation states supported by the same ligand framework bearing sterically imposing and electron‐releasing tBu substituents on the imine carbons of the DIP backbone. Electrochemical analysis demonstrates that the DIP scaffold can retain its ability to serve as an electron reservoir when coordinated to a reduced pnictogen centre, with a reversible reduction observed for the PI complex.

show abstract

Section: Resultsmentioning

confidence: 52%

Diiminepyridine‐Supported Phosphorus(I) and Phosphorus(III) Complexes: Synthesis, Characterization, and Electrochemistry

et al. 2020

View full text Add to dashboard Cite

show abstract

“…Much research has also been performed on I [32][33][34][35][36][37][38], and the synthesis of its analogs with the aim to improve the catalytic performance deserves attention [7,29,[39][40][41][42]. Subtle change in the ligand framework sometimes results in dramatic improvement in the polymerization performance and, hence, modification of the substituents has been a main research theme in the development of postmetallocecenes [43][44][45][46][47][48][49]. Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

Preparation of Pyridylamido Hafnium Complexes for Coordinative Chain Transfer Polymerization

et al. 2020

View full text Add to dashboard Cite

The pyridylamido hafnium complex (I) discovered at Dow is a flagship catalyst among postmetallocenes, which are used in the polyolefin industry for PO-chain growth from a chain transfer agent, dialkylzinc. In the present work, with the aim to block a possible deactivation process in prototype compound I, the corresponding derivatives were prepared. A series of pyridylamido Hf complexes were prepared by replacing the 2,6-diisopropylphenylamido part in I with various 2,6-R2C6H3N-moieties (R = cycloheptyl, cyclohexyl, cyclopentyl, 3-pentyl, ethyl, or Ph) or by replacing 2-iPrC6H4C(H)- in I with the simple PhC(H)-moiety. The isopropyl substituent in the 2-iPrC6H4C(H)-moiety influences not only the geometry of the structures (revealed by X-ray crystallography), but also catalytic performance. In the complexes bearing the 2-iPrC6H4C(H)-moiety, the chelation framework forms a plane; however, this framework is distorted in the complexes containing the PhC(H)-moiety. The ability to incorporate α-olefin decreased upon replacing 2-iPrC6H4C(H)-with the PhC(H)-moiety. The complexes carrying the 2,6-di(cycloheptyl)phenylamido or 2,6-di(cyclohexyl)phenylamido moiety (replacing the 2,6-diisopropylphenylamido part in I) showed somewhat higher activity with greater longevity than did prototype catalyst I.

show abstract

“…In the last two decades, this class of catalysts has received increasing research interest owing to their versatile structures, easy synthesis, and capability to tune structures of products [14]. Therefore, low molecular weight oligomers [15][16][17], ultrahigh molecular weights polyethylenes (UHMWPE) [18,19], highly branched [20] or linear [21][22][23] polymers are readily prepared by facilely tuning the substituents and backbone of ligands [24,25]. Besides, living polymerization of α-olefins has been also achieved by the delicate design of α-diimine based catalysts [26,27].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of Ethylene/1-Octene Copolymers with Ultrahigh Molecular Weights by Zr and Hf Complexes Bearing Bidentate NN Ligands with the Camphyl Linker

et al. 2021

View full text Add to dashboard Cite

Ultrahigh molecular weight polyethylene (UHMWPE) is a class of high-performance engineering plastics, exhibiting a unique set of properties and applications. Although many advances have been achieved in recent years, the synthesis of UHMWPE is still a great challenge. In this contribution, a series of zirconium and hafnium complexes, [2,6-(R1)2-4-R2-C6H2-N-C(camphyl)=C(camphyl)-N-2,6-(R1)2-4-R2-C6H2]MMe2(THF) (1-Zr: R1 = Me, R2 = H, M = Zr; 2-Zr: R1 = Me, R2 = Me, M = Zr; 1-Hf: R1 = Me, R2 = H, M = Hf; 2-Hf: R1 = Me, R2 = Me, M = Hf), bearing bidentate NN ligands with the bulky camphyl backbone were synthesized by the stoichiometric reactions of α-diimine ligands with MMe4 (M = Hf or Zr). All Zr and Hf metal complexes were analyzed using 1H and 13C NMR spectroscopy, and the molecular structures of complexes 1-Zr and 1-Hf were determined by single-crystal X-ray diffraction, revealing that the original α-diimine ligand was selectively reduced into the ene-diamido form and generated an 1,3-diaza-2-metallocyclopentene ring in the metal complexes. Zr complexes 1-Zr and 2-Zr showed moderate activity (up to 388 kg(PE)·mol−1(M)·h−1), poor copolymerization ability, but unprecedented molecular weight capability toward ethylene/1-octene copolymerization. Therefore, copolymers with ultrahigh molecular weights (> 600 or 337 × 104 g∙mol−1) were successfully synthesized by 1-Zr or 2-Zr, respectively, with the borate cocatalyst [Ph3C][B(C6F5)4]. Surprisingly, Hf complexes 1-Hf and 2-Hf showed negligible activity under otherwise identical conditions, revealing the great influence of metal centers on catalytic performances.

show abstract

Ethylene polymerization of nickel catalysts with α-diimine ligands: factors controlling the structure of active species and polymer properties

Abstract: In the present perspective, the recent advances of α-diimine nickel based catalysts of ethylene polymerization, focusing on the relationships between catalyst structures and their catalytic properties are discussed.

Cited by 46 publications

References 68 publications

Diiminepyridine‐Supported Phosphorus(I) and Phosphorus(III) Complexes: Synthesis, Characterization, and Electrochemistry

Diiminepyridine‐Supported Phosphorus(I) and Phosphorus(III) Complexes: Synthesis, Characterization, and Electrochemistry

Preparation of Pyridylamido Hafnium Complexes for Coordinative Chain Transfer Polymerization

Synthesis of Ethylene/1-Octene Copolymers with Ultrahigh Molecular Weights by Zr and Hf Complexes Bearing Bidentate NN Ligands with the Camphyl Linker

Contact Info

Product

Resources

About