Zinc N-heterocyclic carbene complexes and their polymerization of d,l-lactide

Jensen, Tryg R.; Schaller, Chris P.; Hillmyer, Marc A.; Tolman, William B.

doi:10.1016/j.jorganchem.2005.07.070

Cited by 133 publications

(78 citation statements)

References 59 publications

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“…They have shown to be particularly active in reactions involving the fixation of CO 2 , such as the methylation of amines [3], or the synthesis of cyclic carbonates from epoxides [4]. In addition, they are employed in the synthesis of polyurethanes [5] and in the polymerization of D,L-lactide [6]. To date, the synthesis of Zn(II)-NHC complexes involves the addition of a free carbene to a zinc salt.…”

Section: Introductionmentioning

confidence: 99%

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Synthesis, characterization and catalytic activity of stable [(NHC)H][ZnXY2] (NHC =N-Heterocyclic carbene, X, Y = Cl, Br) species

Santoro

Nahra

Cordes

et al. 2016

Journal of Molecular Catalysis A: Chemical

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Graphical Abstract Highlights• A library of stable [(NHC)H][ZnXY 2 ] species was synthesized• The structure of the salts was unambiguously assessed by X-ray diffraction analyses• The catalytic activity of the novel species was tested in the methylation of amines with CO 2 as carbon feedstock AbstractThe synthesis and characterization of imidazol(in)ium-based zinc(II) halide salts are reported.These compounds present interesting structural features and exhibit high stability. Their catalytic activity was explored in the methylation of amines with CO 2 and PhSiH 3 .

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Section: Introductionmentioning

confidence: 99%

“…To date, the synthesis of Zn(II)-NHC complexes involves the addition of a free carbene to a zinc salt. The carbene can either be a priori isolated or generated in situ from an appropriate precursor (NHC salt or NHC-CO 2 adduct) [3][4][5][6][7]. Alternatively, the NHC salt can be directly reacted …”

Section: Introductionmentioning

confidence: 99%

Synthesis, characterization and catalytic activity of stable [(NHC)H][ZnXY2] (NHC =N-Heterocyclic carbene, X, Y = Cl, Br) species

Santoro

Nahra

Cordes

et al. 2016

Journal of Molecular Catalysis A: Chemical

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“…In this context, a great variety of highly active zinc complexes has been prepared. [13a] , [14][15][16][17] But the drawback that restricts the qualification for industrial purposes is their sensitivity to air, moisture and impurities in the monomer. So there is still an exigent need for initiators which possess high polymerisation activity and at the same time a great robustness.…”

Section: Introductionmentioning

confidence: 99%

Tracking the Structure‐Reactivity Relationship of Zinc Guanidine‐Pyridine Hybrid Complexes Initiating Lactide Polymerisation

Börner

Flörke

Döring

et al. 2010

Macromolecular Symposia

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Summary: Three zinc guanidine-pyridine hybrid complexes [Zn(TMGqu) (3) were synthesised, completely characterised and investigated on their activity in the solvent-free ring-opening polymerisation of D,L-lactide. It was proven that the bis-chelate trigonal-bipyramidally coordinated compounds 1 and 3 are able to act as initiators for lactide polymerisation, and polylactides with molecular weights (M w ) of around 28000 g/mol could be obtained with relatively narrow polydispersities. The tetrahedral complex 2 does not initiate lactide polymerisation. In an integrated approach of structural studies and DFT calculations, the active complexes 1 and 3 were analysed towards their structural and electronical pre-requisites in comparison to their more active triflate analogues 1OTf and 3 OTf . The influence of coordination strength of the anionic component on the charge distribution within the complex and on the substrate accessibility to the zinc centre is highlighted as crucial factor for the polymerisation initiation. As result, it is shown that the mesylate complexes 1 and 3 have less positive charge on the zinc centre and the mesylate is stronger bound than the corresponding triflate in the triflate complexes 1OTf and 3 OTf . Consequently, the reactivity of the complexes is directly correlated to the coordinational behaviour of the anionic component.

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“…While in the case of corresponding gallium complexes, a relatively strong Ga-C NHC bond led to stable complexes [1,2], in the case of mostly unstable dialkylindium alkoxides with NHCs, a significantly weaker In-C NHC bond was observed [3]. Consequently, in the ring-opening polymerization with Me 2 GaOR(NHC), Ga-C NHC bond remained intact, resulting in the exclusive insertion of rac-LA into Ga-O alkoxide bond, similar to Zn [14][15][16], Al [17], as well as Ti and Zr [18][19][20], metal alkoxides with NHCs, which have been reported to polymerize rac-LA due to the insertion into [17], as well as Ti and Zr [18][19][20], metal alkoxides with NHCs, which have been reported to polymerize rac-LA due to the insertion into M-Oalkoxide bond. On the other hand, rac-LA could insert, even at low temperature, into In-CNHC bond of Me2GaOR(NHC), considerably weaker in comparison with Ga-CNHC [3].…”

Section: Introductionmentioning

confidence: 99%

Probing the Effect of Six-Membered N-Heterocyclic Carbene—6-Mes—on the Synthesis, Structure and Reactivity of Me2MOR(NHC) (M = Ga, In) Complexes

et al. 2018

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Abstract:The investigation of the reactivity of six membered N-heterocyclic carbene 1,3-bis(2,4,6-trimethylphenyl)-3,4,5,6-tetrahydropyrimidin-1-ylidene (6-Mes) towards dialkylgallium and dialkylindium alkoxides/aryloxides has shown that both steric hindrances and donor properties of 6-Mes significantly influence the strength of M-C 6-Mes bond, as well as the formation, structure and reactivity of Me 2 MOR(6-Mes) (M = Ga, In) complexes. While the reactions of simple dimethylgallium alkoxides with 6-Mes lead to the formation of stable monomeric Me 2 Ga(OCH 2 CH 2 OMe)(6-Mes) (1) and Me 2 GaOMe(6-Mes) complexes, the analogous Me 2 InOR(6-Mes) are unstable and disproportionate to methylindium alkoxides and Me 3 In(6-Mes) (2). The use of bulky alkoxide ligand-OCPh 2 Me or aryloxide ligand-OC 6 H 4 OMe allowed for the synthesis of stable Me 2 M(OCPh 2 Me)(6-Mes) (M = Ga (3) and In (4)) as well as Me 2 M(OC 6 H 4 OMe)(6-Mes) (M = Ga (5) and In (6)). The structures of 1-6 have been determined using both spectroscopic methods in solution and X-ray diffraction studies, which confirmed the effect of both steric hindrances and donor properties of 6-Mes on their structure and catalytic properties in the ring-opening polymerization (ROP) of rac-lactide.

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Zinc N-heterocyclic carbene complexes and their polymerization of d,l-lactide

Cited by 133 publications

References 59 publications

Synthesis, characterization and catalytic activity of stable [(NHC)H][ZnXY2] (NHC =N-Heterocyclic carbene, X, Y = Cl, Br) species

Synthesis, characterization and catalytic activity of stable [(NHC)H][ZnXY2] (NHC =N-Heterocyclic carbene, X, Y = Cl, Br) species

Tracking the Structure‐Reactivity Relationship of Zinc Guanidine‐Pyridine Hybrid Complexes Initiating Lactide Polymerisation

Probing the Effect of Six-Membered N-Heterocyclic Carbene—6-Mes—on the Synthesis, Structure and Reactivity of Me2MOR(NHC) (M = Ga, In) Complexes

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