Highly active zinc alkyl cations for the controlled and immortal ring-opening polymerization of ε-caprolactone

Romain, Charles; Rosa, Vítor; Fliedel, Christophe; Bier, Frédéric; Hild, Frédéric; Welter, Richard; Dagorne, Samuel; Avilés, Teresa

doi:10.1039/c2dt12336c

Cited by 57 publications

(36 citation statements)

References 35 publications

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“…Remarkably, the ε ‐CL polymerization activities (TOF) displayed by our complexes ( Table ) are of the same order of magnitude as those reported for other active mononuclear zinc species …”

Section: Resultssupporting

confidence: 84%

Cubane‐Type Polynuclear Zinc Complexes Containing Tridentate Schiff Base Ligands: Synthesis, Characterization, and Ring‐Opening Polymerization Studies of rac‐Lactide and ε‐Caprolactone

Ghosh

Spannenberg

Mejía

2017

Helvetica Chimica Acta

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New polynuclear zinc complexes containing tridentate Schiff base ligands were successfully synthesized and fully characterized. The solid‐state structure of the complexes was determined using single crystal X‐ray diffraction. The complexes display a tetranuclear cubane‐like core structure [Zn4O4] and sowed good catalytic activity towards the ring‐opening polymerization (ROP) of rac‐lactide (rac‐LA) and ε‐caprolactone (ε‐CL) under solvent‐free conditions. The polylactic acid (PLA) obtained from rac‐LA showed isotactic enrichment, as proved by homonuclear decoupled 1H‐NMR analysis. These complexes also showed good activity and superior control towards the ROP of rac‐LA and ε‐CL in the presence of benzyl alcohol as a co‐initiator. Furthermore, kinetic studies demonstrated that the ROP of rac‐LA and ε‐CL has a first order dependence on both monomer (rac‐LA and ε‐CL) and catalyst concentration.

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Section: Resultssupporting

confidence: 84%

Cubane‐Type Polynuclear Zinc Complexes Containing Tridentate Schiff Base Ligands: Synthesis, Characterization, and Ring‐Opening Polymerization Studies of rac‐Lactide and ε‐Caprolactone

Ghosh

Spannenberg

Mejía

2017

Helvetica Chimica Acta

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“…One would expect solution polymerization to result in higher reaction kinetics due to improved solubility of the catalyst, ease of heat transfer and reduced viscosity of the reaction mixture[33]. Nonetheless, this trend is consistent with our previous reports [16] and has been attributed to reduced concentrations of the active species in solution.…”

supporting

confidence: 89%

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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“…Previously, we have shown that the reactions of the dpp‐bian with Grignard reagents, n BuLi, and group 13 organometallic elements proceeded with alkylation of the dpp‐bian at one of the imino carbon atoms . Related metal complexes with substituted bian ligands were obtained by Dagorne and co‐workers through the reaction of bians with Zn‐based organometallic compounds . These zinc derivatives were found to be highly active catalysts in the ROP of ϵ ‐caprolactone .…”

Section: Resultsmentioning

confidence: 99%

“…Related metal complexes with substituted bian ligands were obtained by Dagorne and co‐workers through the reaction of bians with Zn‐based organometallic compounds . These zinc derivatives were found to be highly active catalysts in the ROP of ϵ ‐caprolactone . A different type of addition to dpp‐bian was reported by Hill and co‐workers in 2011: the reactions of bulky organometallics, for example, K[CH(SiMe 3 ) 2 ] and M[CH(SiMe 3 ) 2 ] 2 (M=Mg, Ca, Sr), with dpp‐bian led to dearomatization of one of the six‐membered rings by addition of the nucleophile to the naphthalene ring .…”

Section: Resultsmentioning

confidence: 99%

Redox‐Active Ligand‐Assisted Two‐Electron Oxidative Addition to Gallium(II)

Fedushkin

Dodonov

Skatova

et al. 2018

Chemistry A European J

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The reaction of digallane (dpp-bian)Ga-Ga(dpp-bian) (2) (dpp-bian=1,2-bis[(2,6-diisopropylphenyl)imino]acenaphthene) with allyl chloride (AllCl) proceeded by a two-electron oxidative addition to afford paramagnetic complexes (dpp-bian)Ga(η -All)Cl (3) and (dpp-bian)(Cl)Ga-Ga(Cl)(dpp-bian) (4). Treatment of complex 4 with pyridine induced an intramolecular redox process, which resulted in the diamagnetic complex (dpp-bian)Ga(Py)Cl (5). In reaction with allyl bromide, complex 2 gave metal- and ligand-centered addition products (dpp-bian)Ga(η -All)Br (6) and (dpp-bian-All)(Br)Ga-Ga(Br)(dpp-bian-All) (7). The reaction of digallane 2 with Ph SnNCO afforded (dpp-bian)Ga(SnPh ) (8) and (dpp-bian)(NCO)Ga-Ga(NCO)(dpp-bian) (9). Treatment of GaCl with (dpp-bian)Na in diethyl ether resulted in the formation of (dpp-bian)GaCl (10). Diorganylgallium derivatives (dpp-bian)GaR (R=Ph, 11; tBu, 14; Me, 15; Bn, 16) and (dpp-bian)Ga(η -All)R (R=nBu, 12; Cp, 13) were synthesized from complexes 3, 10, Bn GaCl, or tBu GaCl by salt metathesis. The salt elimination reaction between (dpp-bian)GaI (17) and tBuLi was accompanied by reduction of both the metal and the dpp-bian ligand, which resulted in digallane 2 as the final product. Similarly, the reaction of complex 10 with MentMgCl (Ment=menthyl) proceeded with reduction of the dpp-bian ligand to give the diamagnetic complex [(dpp-bian)GaCl ][Mg Cl (THF) ] (18). Compounds 11, 12, 13, 15, and 16 were thermally robust, whereas compound 14 decomposed when heated at reflux in toluene to give complex (dpp-bian-tBu)GatBu (19). Both complexes 7 and 19 contain R-substituted dpp-bian ligand: in the former compound the allyl group was attached to the imino-carbon atom, whereas in complex 19, the tBu group was situated on the naphthalene ring. Crystal structures of complexes 3, 8, 9, 10, 13, 14, 18, and 19 were determined by single-crystal X-ray analysis. The presence of dpp-bian radical anions in 3, 6, 8, and 10-16 was determined by ESR spectroscopy.

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Highly active zinc alkyl cations for the controlled and immortal ring-opening polymerization of ε-caprolactone

Abstract: Zinc alkyl cations supported by N,N-BIAN-type bidentate ligands were found to be highly active in the immortal ROP of ε-caprolactone to yield narrowly disperse and chain length-controlled poly(ε-caprolactone), whether in solution or bulk polymerization conditions.

Cited by 57 publications

References 35 publications

Cubane‐Type Polynuclear Zinc Complexes Containing Tridentate Schiff Base Ligands: Synthesis, Characterization, and Ring‐Opening Polymerization Studies of rac‐Lactide and ε‐Caprolactone

Cubane‐Type Polynuclear Zinc Complexes Containing Tridentate Schiff Base Ligands: Synthesis, Characterization, and Ring‐Opening Polymerization Studies of rac‐Lactide and ε‐Caprolactone

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

Redox‐Active Ligand‐Assisted Two‐Electron Oxidative Addition to Gallium(II)

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