Catalytic Synergy Using Al(III) and Group 1 Metals to Accelerate Epoxide and Anhydride Ring-Opening Copolymerizations

Diment, Wilfred T.; Gregory, Georgina L.; Kerr, Ryan W. F.; Phanopoulos, Andreas; Buchard, Antoine; Williams, Charlotte K.

doi:10.1021/acscatal.1c04020

Cited by 55 publications

(93 citation statements)

References 81 publications

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“…[13a] Very recently, we reported a heterodinuclear Al(III)K(I) catalyst for NA/CHO ROCOP, [(ovan)Al(III)K(I)(OAc) 2 ], and in comparison 5 is twice as active under equivalent conditions (TOF = 266 h À 1 , 0.05 mol%, 100 °C). [53] Because phthalic anhydride/CHO ROCOP is a more commonly used monomer, catalyst 5 was also tested using it under otherwise equivalent conditions ([Cat] 0 :[PA] 0 :[CHO] 0 = 1 : 100 : 2000, 0.05 mol%, 100 °C). Catalyst 5 performs well compared to other dinuclear catalysts, such as [(o-van)Zn-(II) 2 (OAc) 2 (TOF = 198 h À 1 , 0.125 mol%, 100 °C) and to Zn(II)Mg(II) catalysts.…”

Section: Chemistry-a European Journalmentioning

confidence: 99%

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

Williams

Reis

Deacy

et al. 2022

Chemistry A European J

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The catalysed ring opening copolymerizations (ROCOP) of carbon dioxide/epoxide or anhydride/epoxide are controlled polymerizations that access useful polycarbonates and polyesters. Here, a systematic investigation of a series of heterodinuclear Mg(II)M(II) complexes reveals which metal combinations are most effective. The complexes combine different first row transition metals (M(II)) from Cr(II) to Zn(II), with Mg(II); all complexes are coordinated by the same macrocyclic ancillary ligand and by two acetate co‐ligands. The complex syntheses and characterization data, as well as the polymerization data, for both carbon dioxide/cyclohexene oxide (CHO) and endo‐norbornene anhydride (NA)/cyclohexene oxide, are reported. The fastest catalyst for both polymerizations is Mg(II)Co(II) which shows propagation rate constants (kp) of 34.7 mM−1 s−1 (CO2) and 75.3 mM−1 s−1 (NA) (100 °C). The Mg(II)Fe(II) catalyst also shows excellent performances with equivalent rates for CO2/CHO ROCOP (kp=34.7 mM−1 s−1) and may be preferable in terms of metallic abundance, low cost and low toxicity. Polymerization kinetics analyses reveal that the two lead catalysts show overall second order rate laws, with zeroth order dependencies in CO2 or anhydride concentrations and first order dependencies in both catalyst and epoxide concentrations. Compared to the homodinuclear Mg(II)Mg(II) complex, nearly all the transition metal heterodinuclear complexes show synergic rate enhancements whilst maintaining high selectivity and polymerization control. These findings are relevant to the future design and optimization of copolymerization catalysts and should stimulate broader investigations of synergic heterodinuclear main group/transition metal catalysts.

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Section: Chemistry-a European Journalmentioning

confidence: 99%

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

Williams

Reis

Deacy

et al. 2022

Chemistry A European J

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“…The best PA/CHO ROCOP catalyst, 3 ZnNa (TOF = 225 h –1 at 0.025 mol % vs CHO) shows an activity at the upper end of class (ii) species. It is only surpassed by an L a Al(III)K(I) catalyst, very recently reported by our team (TOF = 1072 h –1 at 0.05 mol % vs CHO), and by a trinuclear L d (Cr(III)Cl) 3 salen species, activated with three equivalents of PPNCl, reported by Lu and co-workers which showed an outstanding activity (TOF = 10,620 h –1 at 0.0033 mol % vs CHO) . One future area to explore would be to apply the trinucleating salen ligand, used by the Lu group and others, to make mixed metal catalysts.…”

Section: Discussionmentioning

confidence: 77%

“…]: 200 [PA]: 400 [CHO] and 120 °C; for more details see ref . k Literature catalyst tested at 1 [Cat. ]: 400 [PA]: 2000 [CHO] at 100 °C; for more details see ref . l Literature catalyst tested at 1 [Cat. ]: 6000 [PA]: 30,000 [CHO] at 100 °C; for more details see ref . m Literature catalyst tested at 1 [Cat.…”

Section: Discussionmentioning

confidence: 99%

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Heterotrinuclear Ring Opening Copolymerization Catalysis: Structure–activity Relationships

Plajer

Williams

2021

ACS Catal.

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Heteronuclear complexes are highly active catalysts in alternating ring opening copolymerizations (ROCOP) of cyclohexene oxide (CHO)/carbon dioxide or CHO/phthalic anhydride (PA). In this contribution, a series of new trinuclear complexes is investigated through a structure activity study that reveals the influences of ligand electronic properties and metal selection over the catalytic activity and linkage selectivity. The fastest catalyst shows high activity for CHO/CO2 ROCOP at low pressure (1 bar CO2 pressure) and features the ligand coordinated to two Zn(II) centers and with inexpensive and abundant Na(I) (TOF = 1084 h–1, catalyst/CHO 1:4000, 1 bar, 100 °C). High CHO/PA copolymerization activity is achieved with the combination of two Mg(II) and one Na(I) center (TOF = 142 h–1, catalyst/PA/CHO 1:200:4000, 100 °C); further the catalyst undergoes “switchable” epoxide/anhydride ROCOP and epoxide ring opening polymerization (ROP), allowing for controlled polyether block formation. Polymerization kinetic investigations reveal the influences of the ligand electronics, complex stability and metal–metal separation, and their influences over the retention of high activity throughout the catalysis. The findings should help in guiding future polymerization catalyst design, facilitate block polymer production, and inspire other CO2 utilization processes.

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“…The authors tentatively proposed that the bis-alkoxide lithium aluminates partially dissociate into LiOBn and LAlOBn during ROP, with LAlOBn activating the monomer and LiOBn acting as the nucleophile source. In a similar vein, Williams and coworkers recently reported a cooperative potassium aluminate catalyst for epoxide/anhydride ring-opening copolymerisation (Figure 1), [20] with DFT studies showing that Al coordinates the epoxide monomer whilst ring-opening occurs from the K-O carboxylate nucleophile. These studies indicate that available monomer coordination sites at Al may be key, even in the presence of an alkali metal that could act as a weak Lewis acid for monomer activation.…”

Section: Introductionmentioning

confidence: 73%

Incorporating Sodium to Boost the Activity of Aluminium TrenSal Complexes towards rac‐Lactide Polymerisation

2022

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Four novel homo-and heterometallic sodium and/or aluminium complexes based on the TrenSal ligand, [LH 3 ], have been synthesised and fully characterised, including by single-crystal X-ray diffraction experiments. While [LAl] was completely inactive towards rac-lactide ring-opening polymerisation, incorporating sodium to form heterometallic [LNaAlMe] changes the aluminium geometry from octahedral to tetrahedral, leading to good catalytic activity in the presence of co-initiator BnOH (k obs = 3.19 × 10 À 2 min À 1 ; room temperature, toluene solvent) and good polymerisation control. Under identical conditions, homometallic sodium complexes showed higher activities in rac-lactide polymerisation than [LNaAlMe], with [LNa 3 ] being extremely active (k obs = 1.21 min À 1 ) but displaying unusual second-order monomer dependency and poor polymerisation control. 1 H NMR spectroscopic studies suggest that polymerisation with [LNaAlMe] or [LH 2 Na]/BnOH follows an activated monomer mechanism, whereas [LNa 3 ] operates via simultaneous coordination-insertion and activated monomer mechanisms. Overall, heterometallic [LNaAlMe] provides a balance of good activity and control compared to the homometallic analogues.

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Catalytic Synergy Using Al(III) and Group 1 Metals to Accelerate Epoxide and Anhydride Ring-Opening Copolymerizations

Cited by 55 publications

References 81 publications

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

Heterodinuclear Mg(II)M(II) (M=Cr, Mn, Fe, Co, Ni, Cu and Zn) Complexes for the Ring Opening Copolymerization of Carbon Dioxide/Epoxide and Anhydride/Epoxide

Heterotrinuclear Ring Opening Copolymerization Catalysis: Structure–activity Relationships

Incorporating Sodium to Boost the Activity of Aluminium TrenSal Complexes towards rac‐Lactide Polymerisation

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