Synthesis, structure, and catalytic activity of tetracoordinate lanthanide amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln=Nd, Sm, Eu)

Zhou, Shuangliu; Wang, Shao-W.; Yang, Gao-S.; Liu, Xin-Y.; Sheng, En-H.; Zhang, Ke-H.; Cheng, Lin; Huang, Zi-X.

doi:10.1016/s0277-5387(03)00042-1

Cited by 130 publications

(76 citation statements)

References 24 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…In standard conditions, yields up to 80 % (runs 3,4 and 6,7) were observed. From Table 1, the nature of the solvent has a decisive influence on the course of the reaction, as also emphasized in a recent study: 34 in THF, whatever the reagent, lithium or magnesium alkyl, a highly syndiotactic material is formed. On the opposite, if the reaction is performed in toluene, the choice of the alkylating reagent has a great influence.…”

mentioning

confidence: 56%

Lanthanide borohydrido complexes for MMA polymerization: syndio‐ vs iso‐ stereocontrol

Barbier‐Baudry

Bouyer

Bruno

et al. 2005

Applied Organom Chemis

View full text Add to dashboard Cite

mentioning

confidence: 56%

Lanthanide borohydrido complexes for MMA polymerization: syndio‐ vs iso‐ stereocontrol

Barbier‐Baudry

Bouyer

Bruno

et al. 2005

Applied Organom Chemis

View full text Add to dashboard Cite

“…[a] 17] and 2-[(2,6-Me 2 C 6 H 3 )NHCH 2 ]-A C H T U N G T R E N N U N G (C 4 H 3 NH) [12g] were prepared by literature methods. IR spectra were recorded with a SHIMADZU FTIR-8400S spectrometer.…”

Section: Methodsmentioning

confidence: 99%

Highly Efficient Hydrophosphonylation of Aldehydes and Unactivated Ketones Catalyzed by Methylene‐Linked Pyrrolyl Rare Earth Metal Amido Complexes

Zhou

Rong

et al. 2012

Chemistry A European J

View full text Add to dashboard Cite

A series of rare earth metal amido complexes bearing methylene-linked pyrrolyl-amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent-free conditions for liquid substrates. Treatment of [(Me(3)Si)(2)N](3)Ln(μ-Cl)Li(THF)(3) with 2-(2,6-Me(2)C(6)H(3)NHCH(2))C(4)H(3)NH (1, 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(μ-η(5):η(1)):η(1)-2-[(2,6-Me(2)C(6)H(3))NCH(2)](C(4)H(3)N)LnN(SiMe(3))(2)}(2) [Ln=Y (2), Nd (3), Sm (4), Dy (5), Yb (6)] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by (1)H NMR spectroscopic analyses. The structures of complexes 2, 3, 4, and 6 were determined by single-crystal X-ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol%) afforded the products in high yields (up to 99%) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99% with employment of low loadings (0.1 to 0.5 mol%) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α-hydroxy diaryl phosphonates in moderate to high yields.

show abstract

“…[21] Other complexes, which include allyl, [22] alkyl, [23][24][25] lanthanocene, silylene-bridged azaallyl, [26] indenyl, [27] amido, [24,[28][29][30][31] thiolato, [32] halogeno, [33][34][35] or divalent [31,36,37] derivatives, have been reported as efficient initiators for MMA polymerization. Noteworthy is the bimetallic bisA C H T U N G T R E N N U N G (enolato)samariumA C H T U N G T R E N N U N G (III) initiator, generated in situ from the coupling of a radical anion species formed by one-electron transfer from a samarocene catalyst, such as [SmA C H T U N G T R E N N U N G (Cp*) 2 …”

Section: H T U N G T R E N N U N G (Bh 4 ) 3 -A C H T U N G T R E N Nmentioning

confidence: 99%

New Insights into the Polymerization of Methyl Methacrylate Initiated by Rare‐Earth Borohydride Complexes: A Combined Experimental and Computational Approach

Barros

Schappacher

Dessuge

et al. 2008

Chemistry A European J

View full text Add to dashboard Cite

Polymerization of methyl methacrylate (MMA) initiated by the rare-earth borohydride complexes [Ln(BH(4))(3)(thf)(3)] (Ln=Nd, Sm) or [Sm(BH(4))(Cp*)(2)(thf)] (Cp*=eta-C(5)Me(5)) proceeds at ambient temperature to give rather syndiotactic poly(methyl methacrylate) (PMMA) with molar masses M(n) higher than expected and quite broad molar mass distributions, which is consistent with a poor initiation efficiency. The polymerization of MMA was investigated by performing density functional theory (DFT) calculations on an eta-C(5)H(5) model metallocene and showed that in the reaction of [Eu(BH(4))(Cp)(2)] with MMA the borate [Eu(Cp)(2){(OBH(3))(OMe)C=C(Me)(2)}] (e-2) complex, which forms via the enolate [Eu(Cp)(2){O(OMe)C=C(Me)(2)}] (e), is calculated to be exergonic and is the most likely of all of the possible products. This product is favored because the reaction that leads to the formation of carboxylate [Eu(Cp)(2){OOC-C(Me)(=CH(2))}] (f) is thermodynamically favorable, but kinetically disfavored, and both of the potential products from a Markovnikov [Eu(Cp)(2){O(OMe)C-CH(Me)(CH(2)BH(3))}] (g) or anti-Markovnikov [Eu(Cp)(2){O(OMe)C-C(Me(2))(BH(3))}] (h) hydroboration reaction are also kinetically inaccessible. Similar computational results were obtained for the reaction of [Eu(BH(4))(3)] and MMA with all of the products showing extra stabilization. The DFT calculations performed by using [Eu(Cp)(2)(H)] to model the mechanism previously reported for the polymerization of MMA initiated by [Sm(Cp*)(2)(H)](2) confirmed the favorable exergonic formation of the intermediate [Eu(Cp)(2){O(OMe)C=C(Me)(2)}] (e'') as the kinetic product, this enolate species ultimately leads to the formation of PMMA as experimentally observed. Replacing H by BH(4) thus prevents the 1,4-addition of the [Eu(BH(4))(Cp)(2)] borohydride ligand to the first incoming MMA molecule and instead favors the formation of the borate complex e-2. This intermediate is the somewhat active species in the polymerization of MMA initiated by the borohydride precursors [Ln(BH(4))(3)(thf)(3)] or [Sm(BH(4))(Cp*)(2)(thf)].

show abstract

Synthesis, structure, and catalytic activity of tetracoordinate lanthanide amides [(Me3Si)2N]3Ln(μ-Cl)Li(THF)3 (Ln=Nd, Sm, Eu)

Cited by 130 publications

References 24 publications

Lanthanide borohydrido complexes for MMA polymerization: syndio‐ vs iso‐ stereocontrol

Lanthanide borohydrido complexes for MMA polymerization: syndio‐ vs iso‐ stereocontrol

Highly Efficient Hydrophosphonylation of Aldehydes and Unactivated Ketones Catalyzed by Methylene‐Linked Pyrrolyl Rare Earth Metal Amido Complexes

New Insights into the Polymerization of Methyl Methacrylate Initiated by Rare‐Earth Borohydride Complexes: A Combined Experimental and Computational Approach

Contact Info

Product

Resources

About