Nagae Haruki, Matsushiro Saki, Okuda Jun, Mashima Kazushi
Department of Chemistry, Graduate School of Engineering Science, Osaka University Toyonaka Osaka 560-8531 Japan
Institute of Inorganic Chemistry, RWTH Aachen University Landoltweg 1 D-52062 Aachen Germany.
Chem Sci. 2023 Jul 12;14(31):8262-8268. doi: 10.1039/d3sc00974b. eCollection 2023 Aug 9.
We found that a cationic hetero tetranuclear complex including a calcium and three cobalts exhibited high catalytic activity toward alternating copolymerization of propylene oxide (PO) and carbon dioxide (CO). The tertiary anilinium salt [PhNMeH][B(CF)] was the best additive to generate the cationic species while maintaining polymer selectivity and carbonate linkage, even under 1.0 MPa CO. Density functional theory calculations clarified that the reaction pathway mediated by the cationic complex is more favorable than that mediated by the neutral complex by 1.0 kcal mol. We further found that the flexible ligand exchange between Ca and Co ions is important for the alternating copolymerization to proceed smoothly.
我们发现，一种包含一个钙和三个钴的阳离子异四核配合物对环氧丙烷（PO）和二氧化碳（CO₂）的交替共聚表现出高催化活性。叔苯胺盐[PhNMeH][B(C₆F₅)₄]是生成阳离子物种的最佳添加剂，即使在1.0 MPa CO₂ 压力下，也能保持聚合物选择性和碳酸酯键。密度泛函理论计算表明，由阳离子配合物介导的反应途径比由中性配合物介导的反应途径更有利，相差1.0 kcal/mol。我们还发现，钙和钴离子之间灵活的配体交换对于交替共聚的顺利进行很重要。
