Tetrasubstituted Guanidinate Anions as Supporting Ligands in Organoyttrium Chemistry

Lu, Zhiping; Yap, and Glenn P. A.; Richeson, Darrin S.

doi:10.1021/om0009029

Cited by 115 publications

(65 citation statements)

References 27 publications

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“…[4] In the meantime, non-Cp ligands such as amidinates, guanidinates, b-diketiminates, salicylaldiminates, and pincer-type compounds have attracted increasing attention over the past decade. [5][6][7][8][9] Heteroscorpionates derived from bis(pyrazolyl)methane are tripodal and amenable to structural modification by varying the substituents of the pyrazole rings and/or the functional group (Scheme 1). [10] Most research works concentrate on introducing protic functional groups to construct anionic heteroscorpionates that are six-electron donating and formally isolobal as cyclopentadienyls (Cp À ).…”

Section: Introductionmentioning

confidence: 99%

Heteroscorpionate Rare‐Earth Metal Zwitterionic Complexes: Syntheses, Characterization, and Heteroselective Catalysis on the Ring‐Opening Polymerization of rac‐Lactide

Zhang

Cui

2011

Chemistry A European J

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Novel neutral phosphine-modified heteroscorpionate ligand (3,5-Me(2)Pz)(2)CHPPh(2) (1) and its derivatives oxophosphine (2) and iminophosphine (3) heteroscorpionates were synthesized for the first time. These neutral heteroscorpionate ligands displayed unique chemistry towards rare-earth metal tris(alkyl)s [Ln(CH(2)SiMe(3))(3)(thf)(2)] (Ln=Y, Lu, Sc). The reaction between compound 1 and [Ln(CH(2)SiMe(3))(3)(thf)(2)] afforded heteroscorpionate rare-earth metal trialkyl adduct complexes 4a-c. Compounds 2 and 3 were treated with [Ln(CH(2)SiMe(3))(3)(thf)(2)] to give the unprecedented zwitterionic heteroscorpionate rare-earth metal dialkyls 5 and 6, respectively. In the process, the heteroscorpionates transferred to the carbanions by means of methine C-H bond cleavage that was attributed to the presence of the electron-withdrawing groups. In addition the ligand and central metal showed a concerted effect on both the catalytic activity and specific selectivity of complexes 4-6 for the ring-opening polymerization (ROP) of rac-lactide (rac-LA). All the adduct complexes 4 were nonselective and gave atactic polylactide (PLA), probably due to the dissociation of ligand 1 from the active metal center during the polymerization. Strikingly, zwitterionic complexes 5 catalyzed rapid ROP of rac-LA to produce PLAs with heterotacticity up to 0.87. However, the zwitterionic complexes 6 were less active and less selective than 5, which might be on account of the stronger coordination of the tetradentate ligand. Complexes 5 represent rare examples of the selective ROP of rac-LA mediated by rare-earth metal complexes supported by non-bisphenolate ligands.

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Section: Introductionmentioning

confidence: 99%

Heteroscorpionate Rare‐Earth Metal Zwitterionic Complexes: Syntheses, Characterization, and Heteroselective Catalysis on the Ring‐Opening Polymerization of rac‐Lactide

Zhang

Cui

2011

Chemistry A European J

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“…Several examples of alkyl complexes of rare-earth metals supported by guanidinate ligands were published recently. [31][32][33][34] We employed the advantages of the [(Me 3 Si) 2 …”

Section: Introductionmentioning

confidence: 99%

Postmetallocene Lanthanide–Hydrido Chemistry: A New Family of Complexes [{Ln{(Me₃Si)₂NC(NiPr)₂}₂(μ‐H)}₂] (Ln=Y, Nd, Sm, Gd, Yb) Supported by Guanidinate Ligands—Synthesis, Structure, and Catalytic Activity in Olefin Polymerization

Trifonov¹,

Скворцов²,

Lyubov³

et al. 2006

Chemistry A European J

104

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The new family of Lewis base free hydrido complexes of rare‐earth metals supported by guanidinate ligands [{Ln{(Me3Si)2NC(NiPr)2}2(μ‐H)}2] (Ln=Y, Nd, Sm, Gd, Yb) was synthesized and structurally characterized. Single‐crystal X‐ray and solution NMR studies revealed that these complexes are dimeric in both solid state and in [D6]benzene. The dimeric hydrido complexes can adopt eclipsed (Nd, Sm, Gd) or staggered (Y, Yb, Lu) conformations depending on the metal‐atom size. Catalytic activity of these [{Ln{(Me3Si)2NC(NiPr)2}2(μ‐H)}2] complexes in the polymerization of ethylene, propylene, and styrene has been investigated. Complexes of Sm and Y have high catalytic activity in ethylene polymerization (1268 and 442 g mmol−1 atm−1 h−1, respectively).

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“…钪末端氮宾配合物, 钪桥联膦宾配合物和钇氢化物具有丰富的反应性能. Richeson 等于 1998 年首次报道了胍基稀土氯化物的合成 [172] , 之后又有多篇文献报道 [173,174] [175] 或者中性二聚体产物(图 29) [176,177] . 当配体位阻较大时, 生成中性单核氯化物 [178] .…”

Section: 基于含氮配体的稀土金属有机配合物unclassified

“…178,185,186] , 这些配合物在室温下不稳定, 但可以用于原位制备氢化物 [185] . 在 TMEDA 的存在下, 胍基稀土氯化物与 MeLi 在己烷中反应生成热稳定性较好的盐型配合物 [175,177,187] .…”

Section: β-二亚胺稀土金属有机配合物 β-二亚胺是最为重要的双齿配体unclassified

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

Changtao¹,

Wang²,

Chen³

2014

Acta Chim. Sinica

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Rare-earth elements include scandium, yttrium and fifteen lanthanides. Since Wilkinson and Birmingham reported the fist example of rare-earth organometallic complex, the chemistry of rare-earth organometallic complexes has had a great advance during the past sixty years. A variety of Cp containing rare-earth metal complexes, including mono-Cp, bis-Cp, and tri-Cp complexes, have been synthesized. Variation of the size of substituent on Cp ring, introducing the nitrogen or oxygen containing pendant arm to Cp ring or using ansa bis-Cp ligands make the synthesis and stabilization of these three types of rare-earth metal Cp complexes available. The Cp related ligands, such as indenyl and fluorenyl, also have been applied for the rare-earth organometallic complexes. From 1990's, there was a tendency to explore the rare-earth organometallic complexes with ancillary ligands beyond Cp and its derivatives in order to search for more efficient rare-earth metal catalysts. Non-Cp ligands, such as biphenolates, β-diketiminates, amidinates, guanidinates, etc. have been introduced into the chemistry of rare-earth organometallic complexes, and a larger number of non-Cp rare-earth organometallic complexes have been synthesized and characterized. The application of non-cyclopentadienyl ligands not only resulted in the rare-earth organometallic complexes with new structural features, but also the catalysts with high activity and high selectivity for the polymer synthesis and organic synthesis. The rare-earth organometallic complexes catalyze homo-and co-polymerization of olefins as well as specific polymerization of dienes and polar monomers. The discovery of the catalytic system composed of the neutral rare-earth metal dialkyls/borate enables to synthesize some interesting polymers which are difficult to be prepared by using other catalytic system. The rare-earth organometallic complexes are also able to catalyze some important organic reactions, such as hydroamination, hydrophosphinylation, and hydroalkoxylation, etc. Different from the late-translation metal catalyzed organic reactions, most of the rare-earth metal catalyzed ones do not involve oxidative addition and reductive elimination steps. The review describes some important developments of the chemistry of rare-earth organometallic complexes in the past sixty years.

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Tetrasubstituted Guanidinate Anions as Supporting Ligands in Organoyttrium Chemistry

Cited by 115 publications

References 27 publications

Heteroscorpionate Rare‐Earth Metal Zwitterionic Complexes: Syntheses, Characterization, and Heteroselective Catalysis on the Ring‐Opening Polymerization of rac‐Lactide

Heteroscorpionate Rare‐Earth Metal Zwitterionic Complexes: Syntheses, Characterization, and Heteroselective Catalysis on the Ring‐Opening Polymerization of rac‐Lactide

Postmetallocene Lanthanide–Hydrido Chemistry: A New Family of Complexes [{Ln{(Me₃Si)₂NC(NiPr)₂}₂(μ‐H)}₂] (Ln=Y, Nd, Sm, Gd, Yb) Supported by Guanidinate Ligands—Synthesis, Structure, and Catalytic Activity in Olefin Polymerization

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

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Tetrasubstituted Guanidinate Anions as Supporting Ligands in Organoyttrium Chemistry

Cited by 115 publications

References 27 publications

Heteroscorpionate Rare‐Earth Metal Zwitterionic Complexes: Syntheses, Characterization, and Heteroselective Catalysis on the Ring‐Opening Polymerization of rac‐Lactide

Heteroscorpionate Rare‐Earth Metal Zwitterionic Complexes: Syntheses, Characterization, and Heteroselective Catalysis on the Ring‐Opening Polymerization of rac‐Lactide

Postmetallocene Lanthanide–Hydrido Chemistry: A New Family of Complexes [{Ln{(Me3Si)2NC(NiPr)2}2(μ‐H)}2] (Ln=Y, Nd, Sm, Gd, Yb) Supported by Guanidinate Ligands—Synthesis, Structure, and Catalytic Activity in Olefin Polymerization

Sixty Years of the Chemistry of Rare-earth Organometallic Complexes

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Product

Resources

About

Postmetallocene Lanthanide–Hydrido Chemistry: A New Family of Complexes [{Ln{(Me₃Si)₂NC(NiPr)₂}₂(μ‐H)}₂] (Ln=Y, Nd, Sm, Gd, Yb) Supported by Guanidinate Ligands—Synthesis, Structure, and Catalytic Activity in Olefin Polymerization