Ring-opening polymerization of lactides by (pyrazol-1-ylmethyl)pyridine Zn(II) and Cu(II) complexes: Kinetics, mechanism and tacticity studies

Ojwach, Stephen O.; Zaca, Thembisile P.

doi:10.17159/0379-4350/2015/v68a2

Cited by 7 publications

(1 citation statement)

References 34 publications

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“…For instance, backbiting reactions can be eliminated by using a suitable sterically bulky ligand that provides some amount of steric barrier around the metal centre. Several ligands have been explored to obtain the optimum catalytic performance of metal complexes; including amino-phenolate, [33][34][35] salicylaldimine, 32 formamide, 36,37 pyrazolyl, 30,[38][39][40][41] and benzoimidazolyl. [42][43][44] Pyrazole and its derivatives constitute an important group of Ndonor ligands that have been used because of their attractive coordination chemistry.…”

Section: Introductionmentioning

confidence: 99%

Ring opening polymerization of d,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes

et al. 2021

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Section: Introductionmentioning

confidence: 99%

Ring opening polymerization of d,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes

et al. 2021

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Structurally rigid bis(pyrazolyl)pyridine Zn(II) and Cu(II) complexes: Structures and kinetic studies in ring‐opening polymerization of ε‐caprolactone

Zikode

Ojwach

Akerman

2016

Applied Organom Chemis

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Four bis(pyrazolyl)pyridine Zn(II) and Cu(II) carboxylate complexes have been structurally elucidated and used as initiators in the ring‐opening polymerization (ROP) of ε‐carprolactone (ε‐CL). Reactions of bis(3,5‐dimethyl‐pyrazol‐1‐yl)pyridine (L1) with the appropriate Zn(II) and Cu(II) carboxylates afforded the corresponding complexes; [Zn(L1)(C6H5COO)2] (1), [Zn(L1)(2‐Cl‐C6H4COO)2] (2), [Zn(L1)(OAc)2] (3) and [Cu(L1)(OAc)2] (4) in moderate to good yields. Molecular structures of compounds 1, 2, 3 confirmed the presence of one tridentate bound ligand L1 in the metal coordination sphere and two carboxylate anions to give five coordination number around Zn(II) and Cu(II) atoms. Complexes 1, 2, 3, 4 initiated the ROP of ε‐CL at 110 °C to give polymers of moderate molecular weights. Kinetic analyses of the ROP reactions indicate pseudo‐first‐order dependency on ε‐CL monomer and initiator. 1H NMR and mass spectral data established a coordination insertion mechanistic pathway and behaviour of 1, 2, 3, 4 as initiators in the ROP of ε‐CL. Copyright © 2016 John Wiley & Sons, Ltd.

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Ring-opening polymerization of ε-caprolactone catalysed by (pyridyl)benzoazole Zn(II) and Cu(II) complexes

2016

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This paper describes the synthesis of (pyridyl)benzoazole Zn(II) and Cu(II) complexes and their applications as catalysts in ring-opening polymerization (ROP) of e-caprolactone (e-CL). Reactions of 2-(3-pyridyl)-1H-benzimidazole (L1), 2-(2-pyridyl)-1H-benzothiazole (L2) and 2-(2-pyridyl)-1H-benzimidazole (L3) with Zn(II) and Cu(II) acetates produced the corresponding complexes; [Zn 2 (L1) 2 (OAc) 4 )] (1), [Cu 2 (L1) 2 (OAc) 4 ] (2), [Zn(L2)(OAc) 2 )] (3), [Zn(L3)(OAc) 2 )] (4) and [Cu(L3),-(OAc) 2 )] (5). Molecular structures of complexes 2 and 5arevealed that while L1 adopts a monodentate binding mode, through the pyridyl nitrogen atom, L3 exhibits a bidentate coordination mode. All the complexes formed active catalysts in the ROP of e-CL to afford moderate molecular weight polymers. The kinetics of the ROP reactions of e-CL were pseudo-first-order with respect to monomer and catalysts.

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Ring-opening polymerization of lactides by (pyrazol-1-ylmethyl)pyridine Zn(II) and Cu(II) complexes: Kinetics, mechanism and tacticity studies

Cited by 7 publications

References 34 publications

Ring opening polymerization of d,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes

Ring opening polymerization of d,l-lactide and ε-caprolactone catalysed by (pyrazol-1-yl)copper(ii) carboxylate complexes

Structurally rigid bis(pyrazolyl)pyridine Zn(II) and Cu(II) complexes: Structures and kinetic studies in ring‐opening polymerization of ε‐caprolactone

Ring-opening polymerization of ε-caprolactone catalysed by (pyridyl)benzoazole Zn(II) and Cu(II) complexes

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