Influence of multidentate N-donor ligands on highly electrophilic zinc initiator for the ring-opening polymerization of epoxides

Merle, Nicolas; Törnroos, Karl W.; Jensen, Vidar R.; Roux, Erwan Le

doi:10.1016/j.jorganchem.2011.02.015

Cited by 18 publications

(21 citation statements)

References 68 publications

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“…1,18,32 The metal-mediated/coordination ROP mechanism is often employed to achieve higher molecular weight (>50 kg mol −1 ) polyethers, whereas anionic ROP is suitable for lower molecular weight polyethers (polyglycols) with controlled chain-end functionality and narrow distribution. 3,33 For metal-based catalyst systems for coordination ROP of epoxides, 1 those containing aluminum 4,5,33−37 and zinc 14,18,38 are among the most established. Several transition-metal-based catalysts for coordination ROP have been reported.…”

Section: ■ Introductionmentioning

confidence: 99%

“…PPG, however, is a flexible, noncrystalline polymer with a low glass transition temperature ( T g ), making it suitable for applications such as lubricants, antifoaming agents, softeners, and flexible polyurethane foams. Less commonly used polyethers include poly(cyclohexene oxide) (PCHO), which can be prepared from ring-opening polymerizations (ROPs) of cychlohexene oxide (CHO) with a suitable catalyst. − Findings for metal-catalyzed CHO ROP include the production of high-molecular weight polymers, sometimes with broad molecular weight dispersities. − ,− Heterogeneous solid acid catalysts such as montmorillite have also been used giving PCHC with T g of 75 °C . The mechanical properties of PCHO differ from those of PEG and PPO in terms of T g , which for PCHO are found in the range of 58–75 °C, ,,,, resulting in different applications to the more ubiquitous PEG, for example.…”

Section: Introductionmentioning

confidence: 99%

“…For metal-based catalyst systems for coordination ROP of epoxides, those containing aluminum ,,− and zinc ,, are among the most established. Several transition-metal-based catalysts for coordination ROP have been reported. − Of particular relevance to the work reported here, Chen, Chisholm and co-workers showed ROP of propylene oxide (PO) using mono- and dinuclear Cr(III)–salen complexes .…”

Section: Introductionmentioning

confidence: 99%

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Chromium Amino-bis(phenolate) Complexes as Catalysts for Ring-Opening Polymerization of Cyclohexene Oxide

2019

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The chromium(III) amino-bis(phenolate) “ate” complex, {Na[CrCl2 L1]}, 1, where L1 = 6,6′-((1,4-diazepane-1,4-diyl)bis(methylene))bis(2,4-di-tert-butylphenolato) and its derivatives 2–4 (where the phenolate substituents and the diamino linker were varied) were prepared. Single crystals obtained by recrystallization of 1 were shown by X-ray diffraction to be a related octahedral complex, 1′, where one of the O-donors in 1′ is protonated, resulting in a monoanionic ligand and affording a neutral Cr(III) dichloride complex. The ligand [L1] chelates in a meridional fashion and anionic chloride donors reside in a trans axial orientation. Cr(III) amino-bis(phenolate) complexes 1–4 showed good activity toward ring-opening polymerization (ROP) of cyclohexene oxide (CHO) without the use of an added cocatalyst, producing high-molecular weight poly(cyclohexene oxide) where 1 was the most active catalyst. Arrhenius data obtained for the ROP of CHO using 1 revealed an activation barrier of 64.0 ± 9.8 kJ mol–1 and the nonlinear polymer molecular weight growth versus conversion relationship suggests a step-growth polymerization mechanism.

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Section: ■ Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Chromium Amino-bis(phenolate) Complexes as Catalysts for Ring-Opening Polymerization of Cyclohexene Oxide

2019

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“…7d Rapid functionalization of CO 2 by insertion into ZnC bonds and ring‐opening polymerization of epoxides are additional examples of applications of zinc–NHC complexes 16. 17…”

Section: Introductionmentioning

confidence: 99%

Zincocene and Dizincocene N‐Heterocyclic Carbene Complexes and Catalytic Hydrogenation of Imines and Ketones

Jochmann

Stephan

2014

Chemistry A European J

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The N-heterocyclic carbene (NHC) adducts Zn(Cp(R))(2) (NHC)] (Cp(R) =C(5)HMe(4), C(5)H(4) SiMe(3); NHC=ItBu, IDipp (Dipp=2,6-diisopropylphenyl), IMes (Mes=mesityl), SIMes) were prepared and shown to be active catalysts for the hydrogenation of imines, whereas decamethylzincocene [ZnCp*(2)] is highly active for the hydrogenation of ketones in the presence of noncoordinating NHCs. The abnormal carbene complex [Zn(OCHPh(2))(2) (aItBu)](2) was formed from spontaneous rearrangement of the ItBu ligand during incomplete hydrogenation of benzophenone. Two isolated Zn(I) adducts [Zn(2)Cp*(2) (NHC)] (NHC=ItBu, SIMes) are presented and characterized as weak adducts on the basis of (13)C NMR spectroscopic and X-ray diffraction experiments. A mechanistic proposal for the reduction of [ZnCp*(2)] with H(2) to give [Zn(2)Cp*(2)] is discussed.

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“…To date, although the X-ray structures of several metal complexes of chiral bisoxazolines have been reported [6][7][8][9][10], there appear to have been no structural studies of chiral bisoxazolines alone. Here, we report a study of the bisoxazoline, 1, using ab initio density functional theory (DFT) [11,12], in combination with vibrational unpolarised absorption (IR) and vibrational circular dichroism (VCD) [13][14][15][16] spectroscopies.…”

Section: Introductionmentioning

confidence: 99%

Conformational Analysis in Solution of a Chiral BisoxazolineMolecule: Vibrational Circular Dichroism Spectroscopy and DensityFunctional Theory Study

Aamouche

Stephens

2011

International Journal of Spectroscopy

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The conformations of the chiral bisoxazoline: 2,2 -methylenebis[3a,8a-dihydro-8H-indeno[1,2-d]oxazole] (also named IndaBOX), have been studied. Density functional theory (DFT) calculations identify four inequivalent stable conformations. Two, I and II have, C 2 symmetry; two, III and IV, have C 1 symmetry. The electronic energies of I-IV are ordered: I < II < III < IV. The span in energy is <1.0 kcal/mole. Vibrational unpolarised absorption and circular dichroism spectra have been predicted for the four conformations using DFT. Comparison of population-weighted spectra to experimental spectra of CHCl 3 and CDCl 3 solutions in mid-IR region strongly supports the DFT predictions of the number, structures, and relative energies of the conformations of IndaBOX. This shows that DFT predicts spectra with a high degree of reliability. We will undoubtedly illustrate the advantage added by vibrational circular dichroism spectroscopy in conformational analysis and in the absolute configuration determination.

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Influence of multidentate N-donor ligands on highly electrophilic zinc initiator for the ring-opening polymerization of epoxides

Cited by 18 publications

References 68 publications

Chromium Amino-bis(phenolate) Complexes as Catalysts for Ring-Opening Polymerization of Cyclohexene Oxide

Chromium Amino-bis(phenolate) Complexes as Catalysts for Ring-Opening Polymerization of Cyclohexene Oxide

Zincocene and Dizincocene N‐Heterocyclic Carbene Complexes and Catalytic Hydrogenation of Imines and Ketones

Conformational Analysis in Solution of a Chiral BisoxazolineMolecule: Vibrational Circular Dichroism Spectroscopy and DensityFunctional Theory Study

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