Dinuclear Ce(IV) Aryloxides: Highly Active Catalysts for Anhydride/Epoxide Ring-Opening Copolymerization
journal contributionposted on 25.03.2021, 14:35 by Steven J. Gray, Karen Brown, Francis Y. T. Lam, Jennifer A. Garden, Polly L. Arnold
A library of new dinuclear CeIV complexes of the type [NEt4]2[Ce2X6(TP)(sol)2] (X = Cl, ODipp, OSiMe3; sol = py, THF), where TP represents a family of tetraphenolate ligands that control intermetallic distance, are readily made in good yields. The ligands strongly stabilize the cerium +4 oxidation state and allow the incorporation of alkylammonium cocations in an “ate” complex formulation that enables them to be used as soluble, single-component catalysts for the ring-opening copolymerization (ROCOP) of a variety of anhydrides and epoxides. High turnover frequencies (TOFs) are achieved with high ester linkage selectivity, low dispersities, and rates that are highly tunable by the intermetallic distance enforced by the TP ligand, demonstrating that a closely coupled di-CeIV unit provides excellent rates of ROCOP catalysis and that, more generally, rare-earth complexes deserve further attention as ROCOP initiators.
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NEt 4THFtetraphenolate ligandsrare-earth complexessingle-component catalystsTP ligandCe 2 X 6High turnover frequenciesalkylammonium cocationsOSiMe 3intermetallic distancedi-Ce IV unitROCOP catalysisActive Catalystsester linkage selectivityring-opening copolymerizationcontrol intermetallic distanceROCOP initiatorsdinuclear Ce IV complexesTOF