Synthesis and characterization of lithium and yttrium complexes containing tridentate pyrrolyl ligands. Single-crystal X-ray structures of {Li[C4H2N(CH2NMe2)2-2,5]}2 (1) and {[C4H2N(CH2NMe2)2-2,5]YCl2(μ-Cl)·Li(OEt2)2}2 (2) and ring-opening polymerization of ε-caprolactone

Kuo, Pei-Cheng; Chang, Jr-Chieng; Lee, Wen-Yi; Lee, Hon Man; Huang, Jui‐Hsien

doi:10.1016/j.jorganchem.2005.06.024

Cited by 32 publications

(3 citation statements)

References 38 publications

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“…C(11), P(1), N(5), Y(1), and O(1) generated a plane adopting the meridional configuration that bisects the angle formed by the chlorine and the silylalkyl groups. The Cl(1)–Y(1) bond length (2.5632 Å) is slightly shorter than the yttrium terminal chloride bond lengths reported in the literature, owing to the enhanced Lewis acidity of the metal center.…”

Section: Resultsmentioning

confidence: 58%

Efficient and Heteroselective Heteroscorpionate Rare-Earth-Metal Zwitterionic Initiators for ROP of rac-Lactide: Role of σ-Ligand

Mou

Liu

et al. 2014

Macromolecules

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A series of oxophosphine (3,5-Me2Pz)2CHP(R)2O (Pz = pyrazole; R = t Bu (HL1), Cy (HL2)) and iminophosphine (3,5-Me2Pz)2CHP(R)2NAr (R = Cy, Ar = Ph (HL3); R = Ph, Ar = Ph (HL4), Ar = 2,6-Me2-phenyl (HL5)) heteroscorpionate ligands were synthesized. Abstraction of the methide proton of these ligands by rare-earth-metal tris(alkyl)s, Ln(CH2SiMe3)3(THF)2, afforded the corresponding zwitterionic bis(alkyl) complexes L1–5Ln(CH2SiMe3)2(THF) (L1, Ln = Y (1a), Lu (1b); L2, Ln = Y (2a), Lu (2b); L3, Ln = Y (3a), Lu (3b); L4, Ln = Y (4a), Lu (4b); L5, Ln = Y (5a), Lu (5b), while metathesis reaction of the lithium salts of LiL3 and LiL4 with YCl3(THF)2 or YBr3(THF)2 followed by treatment with LiCH2SiMe3 and KN(SiHMe2)2, respectively, afforded the first heteroscorpionate yttrium mixed halogen/alkyl or amido complexes L3–4Y(Cl)(CH2SiMe3)(THF) (L3 (6a), L4 (7a)), L3–4Y(Cl)(N(SiHMe2)2)(THF) (L3 (8a), L4 (9a)), L4Y(Br)(CH2SiMe3)(THF) (10a), and L4Y(Br)(N(SiHMe2)2)(THF) (11a). The structures of these complexes were well-defined, and the molecular structures of 1a, 2a, 3b, 4b, 5a, and 7a were further characterized by single crystal X-ray diffraction analysis. Complexes 1–5 showed similar high activity toward the ROP of rac-LA at room temperature, and both the alkyl species participated in initiation, of which the lutetium complexes exhibited slightly higher selectivity than their yttrium analogues (P r = 0.85–0.89 vs 0.80–0.84) despite the bulkiness of the ligands. Interestingly, the mixed halogen complexes 6a–11a were single-site initiators, where the σ-halogen moiety remaining on the central metal showed, for the first time, facilitating the heteroselectivity up to P r = 0.98. This result sheds new light on designing specifically selective catalytic precursors.

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Section: Resultsmentioning

confidence: 58%

Efficient and Heteroselective Heteroscorpionate Rare-Earth-Metal Zwitterionic Initiators for ROP of rac-Lactide: Role of σ-Ligand

Mou

Liu

et al. 2014

Macromolecules

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“…This structural motif is very rare in lithium chemistry and unknown for sodium compounds [5,[12][13][14].…”

Section: Methodsmentioning

confidence: 99%

New Development in Rare Earth Metal Complexes Containing Anionic Bis(imino)pyrrolyl and Bis(phosphanyl)amide Ligands

Jenter

Roesky

2010

Zeitschrift anorg allge chemie

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“…Such inertness is not surprising, given the lack of precedent for chloride ligands to initiate ROP [127].…”

Section: (L ¼ 2-((arylimino)mentioning

confidence: 99%

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.

show abstract

Synthesis and characterization of lithium and yttrium complexes containing tridentate pyrrolyl ligands. Single-crystal X-ray structures of {Li[C4H2N(CH2NMe2)2-2,5]}2 (1) and {[C4H2N(CH2NMe2)2-2,5]YCl2(μ-Cl)·Li(OEt2)2}2 (2) and ring-opening polymerization of ε-caprolactone

Cited by 32 publications

References 38 publications

Efficient and Heteroselective Heteroscorpionate Rare-Earth-Metal Zwitterionic Initiators for ROP of rac-Lactide: Role of σ-Ligand

Efficient and Heteroselective Heteroscorpionate Rare-Earth-Metal Zwitterionic Initiators for ROP of rac-Lactide: Role of σ-Ligand

New Development in Rare Earth Metal Complexes Containing Anionic Bis(imino)pyrrolyl and Bis(phosphanyl)amide Ligands

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

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