Bis(amido) rare-earth complexes coordinated by tridentate amidinate ligand: synthesis, structure and catalytic activity in the polymerization of isoprene and rac-lactide

Tolpygin, Aleksei O.; Linnikova, O. A.; Glukhova, Tatyana A.; Cherkasov, Anton V.; Fukin, Georgy K.

doi:10.1039/c5ra27960g

Cited by 18 publications

(6 citation statements)

References 66 publications

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“…It was previously shown 59 that the use of AliBu 2 H instead of AliBu 3 in the ternary systems [Ln]/borate/10AlR 3 allows obtaining polyisoprene samples with a narrower molecular weight distribution while maintaining the high catalytic activity of the system. However, due to the high efficiency of AliBu 2 H as a chain-transfer agent, 60 the M n value of the polymers is reduced.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

et al. 2021

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The isolable bis(tetramethylaluminate) lanthanide complexes [2-R2,6-XC6H4NC(tBu)(2,6-R1 2C6H3)]Ln(AlMe4)2 (R1 = R2 = X = Me, Ln = La (1); R1 = R2 = X = Me, Ln = Nd (2); R1 = iPr, R2 = H, X = OMe, Ln = La (3); R1 = iPr, R2 = H, X = OMe, Ln = Nd (4)) coordinated by bi- and tridentate amidinate ligands were synthesized by the reactions of the amidines 2,6-Me2C6H3NC(tBu)NH-2,6-Me2C6H3 and 2,6-iPr2C6H3NC(tBu)NH-2-MeOC6H4 with Ln(AlMe4)3 (Ln = La, Nd) and were isolated in 81, 75, 86, and 74% yields, respectively. X-ray analyses revealed that complexes 3 and 4 feature intramolecular coordination of an OMe group to the metal ions. Both AlMe4 fragments in complexes 3 and 4 coordinate to the metal centers in a κ2 mode, while in Nd complex 2 one AlMe4 group adopts a κ2 and the second a κ3-coordination mode. Complexes 1–4 were evaluated as precatalysts for isoprene polymerization. The ternary catalytic systems 1–4/[Ph3C][B(C6F5)4],[PhNHMe2][B(C6F5)4]/nAlR3 (AlR3 = AlMe3, n = 10; AliBu2H, n = 1; AliBu3, n = 10) enable 82–100% conversions of 1000 equiv of monomer at 25 °C within 5–60 min. cis-1,4-Selectivity of the ternary catalytic systems proved to be affected by the type of ligand, the borate, the AlR3 cocatalyst, and the nature of the metallo center and varied in the range of 34.4–91.8%. The binary systems 1–4/[Ph3C][B(C6F5)4],[PhNHMe2][B(C6F5)4] also catalyze isoprene polymerization and afford polyisoprenes containing 96.2–99.0% of cis-1,4 units in polymer chains. The stereoselectivity of binary systems containing complex 1 dramatically depends on the type of borate: 66.8% of trans-1,4 for [Ph3C][B(C6F5)4] and 87.8% of cis-1,4 for [PhNHMe2][B(C6F5)4].

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Section: ■ Results and Discussionmentioning

confidence: 99%

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

et al. 2021

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“…A comparison of catalytic performance in isoprene polymerization of ternary systems based on bis(tetramethylaluminates) 1 and 2 and the previously reported bis(amide) complexes 6* and7* ({2-[Ph 2 P(O)]C 6 H 4 NC(tBu)N(2,6-Me 2 C 6 H 3 )}Ln(N-(SiMe 3 ) 2 ) 2 ), Ln = Nd (6*), La (7*)) 25 revealed a significant influence of the "actor group" on activity and selectivity. Thus, neodymium amido complex 6* is significantly more active in comparison to the related 2.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…24 Nd, La) revealed a significant effect of the "actor group" on the activity and selectivity of the catalytic system as well as on the molecular weight distribution of the obtained polyisoprenes. 25 In order to develop new, efficient catalytic systems for isoprene polymerization based on complexes of lanthanides featuring large ionic radii (La, Nd, Sm), we focused on the synthesis of bis(tetramethylaluminate) complexes supported by the tridentate amidinate ligands {2-[Ph…”

Section: ■ Introductionmentioning

confidence: 99%

“…Recently we demonstrated that the bis(alkyl) complexes {2-[Ph 2 P(O)]C 6 H 4 NC( t Bu)N(2,6-Me 2 C 6 H 3 )}Ln(CH 2 SiMe 3 ) 2 (THF) n (Ln = Y, n = 1; Ln = Er, n = 1; Ln = Lu, n = 0) coordinated by a tridentate amidinate ligand with a pendant Ph 2 PO group form ternary catalytic systems (Ln/borate/10Al i Bu 3 ) which enable highly stereoselective (up to 96.6% cis -1,4) isoprene polymerization . A comparative study with the related bis(amido) complexes {2-[Ph 2 P(O)]C 6 H 4 NC( t Bu)N(2,6-Me 2 C 6 H 3 )}Ln[N(SiMe 3 ) 2 ] 2 , (Ln = Y, Nd, La) revealed a significant effect of the “actor group” on the activity and selectivity of the catalytic system as well as on the molecular weight distribution of the obtained polyisoprenes . In order to develop new, efficient catalytic systems for isoprene polymerization based on complexes of lanthanides featuring large ionic radii (La, Nd, Sm), we focused on the synthesis of bis(tetramethylaluminate) complexes supported by the tridentate amidinate ligands {2-[Ph 2 PX]C 6 H 4 NC( t Bu)N(2,6-Me 2 C 6 H 3 )} − with pendant hard (PO) and soft (PS) Lewis bases.…”

Section: Introductionmentioning

confidence: 99%

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Bis(tetramethylaluminate) Lanthanide Complexes Supported by Amidinate Ligands with a Pendant Ph₂P═X (X = O, S) Group: Application in Isoprene Polymerization

et al. 2021

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A series of bis(tetramethylaluminate) lanthanide complexes {2-[Ph2PX]C6H4NC(tBu)N(2,6-Me2C6H3)}Ln(AlMe4)2 (X = O, Ln = La (1); X = O, Ln = Nd (2); X = O, Ln = Sm (3); X = S, Ln = La (4); X = S, Ln = Nd (5)) coordinated by tridentate amidinate ligands bearing a hard (PO) or soft (PS) donor group were synthesized in 82, 71, 54, 77, and 69% yields, respectively. An X-ray analysis revealed that complexes 1–5 feature an intramolecular coordination of the Ph2PX group to the metal ion and both AlMe4 fragments coordinate to the metal center in a κ2 fashion. The binary systems containing Nd complexes 2 and 5 in combination with [Ph3C][B(C6F5)4] (TB) or [PhNHMe2][B(C6F5)4] (HNB) have high catalytic activity in isoprene polymerization. The activity of 5 containing a soft Lewis base (PS) in the presence of both TB and HNB was much higher in comparison to that of 2 bearing a hard PO group. For the ternary systems 1–5/TB,HNB/nAlR3 (AliBu3, n = 10; AliBu2H, n = 1; AlMe3, n = 10; toluene, room temperature) record reaction rates were observed for neodymium complex 5: in combination with TB, HNB, and AliBu3 it enables quantitative polymerization of 1000 equiv of monomer within 5 min. The effect of the nature of the pendant donor group (hard PO vs soft PS) on the catalytic activity of the ternary systems is clearly manifested only in the case of neodymium complexes 2 and 5: the systems based on complex 5 have much higher activity in comparison to 2. The systems 4/TB,HNB/10AliBu3 and 5/TB/10AliBu3 provide the best stereoselectivities and enable formation of polyisoprene with 73.9–77.4% content of cis-1,4-units. These systems allow for the synthesis of polyisoprenes with a rather narrow polydispersity (M w/M n = 1.17–1.83).

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“…20 However, the systematic comparison of these two kinds of rare-earth metal complexes LLnR 2 (R = −CH 2 C 6 H 4 NMe 2 -o, −CH 2 SiMe 3 , and -N(SiHMe 2 ) 2 ) in structure−reactivity relationship remains scarce. 20,21 On the other hand, trans-1,4-polyisoprene is an ideal component for high-performance tires, 22 and rare-earth metal complexes have exhibited high efficiency in promoting the regio-and stereoselective polymerization of isoprene 9,23,24 ; in contrast, rare-earth metal catalysts for highly trans-1,4-selective polymerization of isoprene are limited. 25−37 Herein, we report the synthesis and characterization of the entire Ln (III) size range (Ln = Sc, Y, La, Sm and Lu) of rareearth metal bis(alkyl)/bis(benzyl)/bis(amide) complexes supported by a tridentate monoanionic amidinate ligand [(2,6-i Pr 2 C 6 H 3 )NC(Ph)N(C 6 H 4 -2-OMe] − as well their application in isoprene polymerization.…”

Section: ■ Introductionmentioning

confidence: 99%

Rare-Earth Metal Complexes Supported by A Tridentate Amidinate Ligand: Synthesis, Characterization, and Catalytic Comparison in Isoprene Polymerization

Tang,

Chen,

Chen

et al. 2024

Inorg. Chem.

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To systematically investigate the dependence of the initiating group and metal size on polymerization performance, a family of rare-earth metal bis(alkyl)/bis(benzyl)/bis(amide) complexes supported by a monoanionic tridentate amidinate ligand [(2,6- i Pr2C6H3)NC(Ph)N(C6H4-2-OMe]− (HL) were synthesized and well-characterized. Treatment of rare-earth metal tris(alkyl)/tris(benzyl)/tris(amide) complexes Y(CH2C6H4NMe2-o)3 or Y(CH2SiMe3)3(THF)2 or Ln[N(SiHMe2)2]3(THF) x (Ln = Sc, x = 1; Ln = Y, La, Sm, Lu, x = 2) with 1 equiv of HL gave the corresponding mono(amidinate) rare-earth metal bis(alkyl)/bis(benzyl)/bis(amide) complexes [(2,6- i Pr2C6H4)NC(Ph)N(C6H4-2-OMe)]Y(CH2C6H4NMe2-o)2 (1), [(2,6- i Pr2C6H4)NC(Ph)N(C6H4-2-OMe)]Y(CH2SiMe3)2(THF) (2), and [(2,6- i Pr2C6H4)NC(Ph)N(C6H4-2-OMe)]Ln[N(SiHMe2)2]2(THF) n (Ln = Y, n = 1 (3); Ln = La, n = 1 (4); Ln = Sc, n = 0 (5); Ln = Lu, n = 0 (6); Ln = Sm, n = 0 (7)) in good isolated yields. These complexes were characterized by elemental analysis, NMR spectroscopy, and single-crystal X-ray diffraction. In the presence of excess AlMe3 and on treatment with 1 equiv of [Ph3C][B(C6F5)4], these complexes could serve as precatalysts for cationic polymerization of isoprene, in which the dependence of the polymerization activity and regioselectivity on the initiating group and metal size was observed.

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Bis(amido) rare-earth complexes coordinated by tridentate amidinate ligand: synthesis, structure and catalytic activity in the polymerization of isoprene and rac-lactide

Abstract: Rare-earth bis(amides) {2-[Ph2Р(O)]C6H4NC(tBu)N(2,6-Me2C6H3)}Ln(N(SiMe3)2)2 (Ln = Y, Nd, La) coordinated by tridentate amidinate ligand were synthesized, structurally characterized and evaluated as catalysts for isoprene and rac-lactide polymerizations.

Cited by 18 publications

References 66 publications

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Amidinate Ligands with a Pendant Ph₂P═X (X = O, S) Group: Application in Isoprene Polymerization

Rare-Earth Metal Complexes Supported by A Tridentate Amidinate Ligand: Synthesis, Characterization, and Catalytic Comparison in Isoprene Polymerization

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Bis(amido) rare-earth complexes coordinated by tridentate amidinate ligand: synthesis, structure and catalytic activity in the polymerization of isoprene and rac-lactide

Abstract: Rare-earth bis(amides) {2-[Ph2Р(O)]C6H4NC(tBu)N(2,6-Me2C6H3)}Ln(N(SiMe3)2)2 (Ln = Y, Nd, La) coordinated by tridentate amidinate ligand were synthesized, structurally characterized and evaluated as catalysts for isoprene and rac-lactide polymerizations.

Cited by 18 publications

References 66 publications

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Bi- and Tridentate Amidinate Ligands: Performance in Isoprene Polymerization

Bis(tetramethylaluminate) Lanthanide Complexes Supported by Amidinate Ligands with a Pendant Ph2P═X (X = O, S) Group: Application in Isoprene Polymerization

Rare-Earth Metal Complexes Supported by A Tridentate Amidinate Ligand: Synthesis, Characterization, and Catalytic Comparison in Isoprene Polymerization

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Bis(tetramethylaluminate) Lanthanide Complexes Supported by Amidinate Ligands with a Pendant Ph₂P═X (X = O, S) Group: Application in Isoprene Polymerization