Bimetallic nickel complexes containing imidazole-based phenolate ligands as efficient catalysts for the copolymerization of carbon dioxide with epoxides

The utilization of hexadentate imidazole-derived diamine-bisphenolate ligands to construct structurally well-defined bimetallic nickel catalysts that enable the mediation of the copolymerization of carbon dioxide with alicyclic epoxides was reported for the first time. A series of dinickel carboxyla...

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Published in:Dalton transactions : an international journal of inorganic chemistry 2023-12, Vol.53 (1), p.299-314
Main Authors: Hsu, Han-Fang, Liu, Guan-Lin, Su, Yu-Chia, Ko, Bao-Tsan
Format: Article
Language:English
Subjects:
Bimetals
Carbon dioxide
Catalysis
Catalysts
Copolymerization
Diamines
Imidazole
Ligands
Nickel
Polymerization
Single crystals
Structural analysis
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Summary:The utilization of hexadentate imidazole-derived diamine-bisphenolate ligands to construct structurally well-defined bimetallic nickel catalysts that enable the mediation of the copolymerization of carbon dioxide with alicyclic epoxides was reported for the first time. A series of dinickel carboxylate/nitrophenolate complexes were facilely prepared through a one-pot procedure and their structures were fully determined by single crystal X-ray structural analysis. Dinickel complexes 1-10 were used as single-component catalysts, and were evaluated for the copolymerization of CO 2 and cyclohexene oxide (CHO), for which acetato-incorporated complex 1 was proved to exhibit the best activity. Not only has the controllability of binickel catalyst 1 for CO 2 /CHO copolymerization been demonstrated, but also an "immortal" character for the same polymerization has been realized. Furthermore, detailed kinetic studies of polymerization catalysis of this type were undertaken, and the kinetics results revealed a first-order dependence on both Ni complex 1 and CHO concentrations. This is a successful example of the introduction of the easily accessible nitrogen-heterocycle group, the imidazole moiety, into phenolate ligands for the development of high-performance homogeneous catalysts towards the bimetallic complex-catalyzed copolymerization of CO 2 and epoxides. In this study, a series of new structurally well-defined dinickel complexes containing imidazole-based diamine-bisphenolate ligands were found to effectively catalyze the ring-opening copolymerization (ROCOP) of CO 2 and cyclohexene oxide.
ISSN:1477-9226
1477-9234
DOI:10.1039/d3dt03084a