Highly stereospecific polymerization of isoprene with homogeneous binary Ziegler-Natta catalysts based on NCN-pincer neodymium precursor

Liu, Dongtao; Cui, Dongmei; Gao, Wei

doi:10.1007/s11426-010-4041-9

Cited by 10 publications

(4 citation statements)

References 14 publications

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“…The aryldiimine NCN-pincer stabilized neodymium dichloride activated by aluminum alkyls generated a new type of homogeneous binary Ziegler−Natta catalyst system exhibiting high cis-1,4 selectivity for the polymerization of isoprene 217 (Figure 55).…”

Section: Catalysts Based On Transition Metal and Lanthanide Complexes...mentioning

confidence: 99%

Dienes Polymerization: Where We Are and What Lies Ahead

Ricci¹,

Pampaloni

Sommazzi

et al. 2021

Macromolecules

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Recently, the research activity in the field of the stereospecific polymerization of conjugated dienes has focused on the use of catalysts based on organometallic complexes having a well-defined structure and containing ligands of various types (e.g., phosphines, bis-imines, and pyridylimines), since it has been observed that the nature of the ligand, as expected on the basis of the diene polymerization mechanism proposed several years ago by Porri, is able to exert a strong influence on the polymerization regioand stereoselectivity, on the polymer molecular weights and their distribution, and in some cases to impart a living feature to the catalysts themselves. In this Perspective we highlight the most recent results obtained in this field and discuss possible future developments in this area.

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Section: Catalysts Based On Transition Metal and Lanthanide Complexes...mentioning

confidence: 99%

Dienes Polymerization: Where We Are and What Lies Ahead

Ricci¹,

Pampaloni

Sommazzi

et al. 2021

Macromolecules

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“…As seen in other studies, the high cis-1,4 selectivity endured at polymerization temperatures up to 80 C and did not vary with different lanthanide metals. In-depth mechanistic [134]. Once again, this system exhibited high activity and high cis-1,4 selectivity for the polymerization of isoprene.…”

Section: Polymerization Of Dienesmentioning

confidence: 76%

Rare Earth Pincer Complexes: Synthesis, Reaction Chemistry, and Catalysis

Hänninen

Zamora

Hayes

2015

The Privileged Pincer-Metal Platform: Coordination Chemistry &Amp; Applications

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The research field surrounding rare earth pincer complexes has reached a stage where a comprehensive review about the reactivity and catalytic behavior of these species is justified. In this contribution, we begin with a brief introduction on common strategies for the preparation of rare earth pincer complexes, continuing with a section devoted to the versatile reactivity observed for this class of compound. Thereafter, several types of compounds are discussed, including extremely reactive hydrides, cationic species, and intriguing scandium imido complexes. Finally, the last portion of this chapter sums up the hitherto reported catalytic studies, including discussions on ring-opening polymerization of cyclic esters, polymerization of olefins and hydroamination reactions, as well as several examples of more infrequently encountered catalytic processes.

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“…To date, a variety of catalyst systems have been reported for the polymerizations of conjugated dienes, among which catalysts based on rare-earth metals have attracted special attention because of their high activity and high regio- and stereoselectivity . Recently, our group has reported a series of pincer-type rare-earth metal halogens and alkyl complexes, which show high activity and excellent cis -1,4-selectivity toward the polymerizations of conjugated dienes upon activation with both organoborate and aluminum alkyls. Thus the catalytic performances of the pincer-type NNN-tridentate pyrrolyl rare-earth metal alkyl complexes obtained in this work have been investigated for the polymerization of isoprene (IP).…”

Section: Resultsmentioning

confidence: 99%

NNN-Tridentate Pyrrolyl Rare-Earth Metal Complexes: Structure and Catalysis on Specific Selective Living Polymerization of Isoprene

2012

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The acid–base reactions of NNN-tridentate pyrrolyl ligands (HL1: 2,5-bis((pyrrolidin-1-yl)methylene)-1H-pyrrole; HL2: 2,5-bis((piperidino)methylene)-1H-pyrrole) with rare-earth metal tris(alkyl)s, Ln(CH2SiMe3)3(THF)2, afforded the corresponding bis(alkyl) complexes L1Ln(CH2SiMe3)2(THF) x (Ln = Sc, x = 0 (1a); Ln = Y, x = 1 (1b); Ln = Lu, x = 1 (1c)), L2Sc(CH2SiMe3)2 (2a), and L2 2Ln2(CH2SiMe3)4 (Ln = Y (2b); Lu (2c)) in moderate to high yields. X-ray diffraction analysis revealed that the scandium complexes 1a and 2a are THF solvent-free monomers where the ligands coordinate to the Sc3+ ion in a κ1:κ2 mode, while the yttrium and lutetium complexes 1b and 1c have the same ligand coordination geometry to that of the scandium complex but are one-THF solvates; complex 2b, however, is a dimer bridged by two anionic L2 fragments that coordinate to the two yttrium ions in mixed η5:η5/κ1:κ1 coordination modes. Upon activation with an organoborate, all these complexes initiated the controlled polymerization of isoprene. In general, complexes 2a–c, bearing ligand L2, exhibited higher activity than the analogous complexes 1a–c, attached to the L1 ligand. Complex 2b, in which the L2 ligand adopts the mixed η5/κ1 coordination mode, showed the highest activity and livingness mode toward the polymerization of isoprene with high cis-1,4-selectivity (94.1%), and both scandium complexes 1a and 2a exhibited high 3,4-selectivity (87%) irrespective of the ligand type; in contrast, the lutetium complexes initiated the atactic isoprene polymerization. The influences of thell ligand structural factors, the coordination solvent, and the central metal ion on the catalytic activity and selectivity are discussed.

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Highly stereospecific polymerization of isoprene with homogeneous binary Ziegler-Natta catalysts based on NCN-pincer neodymium precursor

Cited by 10 publications

References 14 publications

Dienes Polymerization: Where We Are and What Lies Ahead

Dienes Polymerization: Where We Are and What Lies Ahead

Rare Earth Pincer Complexes: Synthesis, Reaction Chemistry, and Catalysis

NNN-Tridentate Pyrrolyl Rare-Earth Metal Complexes: Structure and Catalysis on Specific Selective Living Polymerization of Isoprene

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