Synthesis and characterization of anionic lanthanide complexes {[o-(Me3SiN)2C6H4]Ln(MeC5H4)2}{Li(DME)3} (Ln=Yb, Sm, Nd) and their catalytic activity for the polymerization of methyl methacrylate

Zhou, Lipeng; Sheng, Hongting; Yao, Yingming; Zhang, Yong; Shen, Qi

doi:10.1016/j.jorganchem.2007.03.016

Cited by 15 publications

(1 citation statement)

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“…3,[9][10][11][12][13] Other organolanthanide precursors were reported to similarly favor the syndiotactic enrichment of PMMA, however, not to such a large extent. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30] On the other hand, isotactic-enriched PMMA prepared from related group 3 metals are much less common. [31][32][33][34] Regarding rare earth borohydride derivatives, mono-, bis-or tris-borohydridodiamide-diamine, guanidinate, amino-or alkylsubstituted cyclopentadienyl, and alkoxide complexes have been recently reported to polymerize MMA.…”

Section: Introductionmentioning

confidence: 99%

Bis(phosphinimino)methanide borohydride complexes of the rare-earth elements as initiators for the polymerization of methyl methacrylate: combined experimental and computational investigations

Guillaume¹,

Brignou²,

Susperrégui³

et al. 2011

Polym. Chem.

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International audienceRare earth borohydride complexes are known as efficient initiators for the polymerization of both apolar and polar monomers. Significant contribution of the phosphiniminomethanide ligand on the reactivity of group 3 derivatives was previously established in the polymerization of ε-caprolactone. Investigations of the capability of bis(phosphinimino)methanide rare earth metal bisborohydrides, [{CH(PPh2NSiMe3)2}La(BH4)2(THF)] (1) and [{CH(PPh2NSiMe3)2}Ln(BH4)2] (Ln = Y (2), Lu (3)) to polymerize methyl methacrylate (MMA) both experimentally and computationally, are reported here. All three metallic compounds allowed the preparation of PMMA at room temperature. However, the overall performances of 1-3 remain quite poor based on experimental observations. DFT investigations on the insertion of the first two MMA molecules revealed that the incoming of the first MMA molecule was the most important step regardless of the nature of the metal center. The nucleophilic attack of MMA leads to the formation of a first adduct B followed by the unprecedented trapping of the liberated BH3 group by the nitrogen of the phosphiniminomethanide ligand to afford the active enolate species C. The unique significant role played by the phosphiniminomethanide ligand has thus been clearly unveiled and evidenced computationally. This whole first insertion of the MMA process is both kinetically and thermodynamically favorable. Trapping of the BH3 by the ancillary ligand appeared to make the second MMA insertion more energetically favorable than the first one, especially for lanthanum. The ketoenolate thus formed, Prod., is thermodynamically and kinetically favorable. In the case of yttrium, steric considerations, in addition to energetically comparable first and second MMA insertions , support the experimentally observed difficulty to polymerize MMA. DFT calculations closely corroborate experimental findings

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Section: Introductionmentioning

confidence: 99%

Bis(phosphinimino)methanide borohydride complexes of the rare-earth elements as initiators for the polymerization of methyl methacrylate: combined experimental and computational investigations

Guillaume¹,

Brignou²,

Susperrégui³

et al. 2011

Polym. Chem.

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Lanthanide(II) amide complexes: Efficient initiators for the living polymerization of methyl methacrylate

Zhou

Yao

Shen

2009

J of Applied Polymer Sci

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Lanthanide(II) complexes supported by amido ligands, [(C 6 H 5 [Ln ¼ Sm (3) or Yb (4); THF ¼ tetrahydrofuran], were found to initiate the polymerization of methyl methacrylate (MMA) as efficient single-component initiators (in toluene for 3 and 4 and in toluene with a small amount of THF for 1 and 2) to produce syndiotactic polymers. The catalytic behavior was highly dependent on both the amido ligand and the polymerization temperature. Initiators 3 and 4 initiated MMA polymerization over a wide range of temperatures (20 C to À40 C), whereas the polymerization with 1 and 2 proceeded smoothly only at low temperatures ( 0 C). The kinetic behavior and some features of the polymerizations of MMA initiated by 3 and 4 were studied at À40 C. The polymerization rate was first-order with the monomer concentration. The molar masses of the polymers increased linearly with the increase in the polymer yields, whereas the molar mass distributions remained narrow and unchanged throughout the polymerization; this indicated that these systems had living character. A polymerization mechanism initiated by bimetallic bisenolate formed in situ was proposed.

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Synthesis and Characterization of Heteroscorpionate Rare‐Earth Metal Dialkyl Complexes and Catalysis on MMA Polymerization

2010

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Synthesis and characterization of anionic lanthanide complexes {[o-(Me3SiN)2C6H4]Ln(MeC5H4)2}{Li(DME)3} (Ln=Yb, Sm, Nd) and their catalytic activity for the polymerization of methyl methacrylate

Cited by 15 publications

References 37 publications

Bis(phosphinimino)methanide borohydride complexes of the rare-earth elements as initiators for the polymerization of methyl methacrylate: combined experimental and computational investigations

Bis(phosphinimino)methanide borohydride complexes of the rare-earth elements as initiators for the polymerization of methyl methacrylate: combined experimental and computational investigations

Lanthanide(II) amide complexes: Efficient initiators for the living polymerization of methyl methacrylate

Synthesis and Characterization of Heteroscorpionate Rare‐Earth Metal Dialkyl Complexes and Catalysis on MMA Polymerization

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