苏州大学姚英明团队报道了氨基桥接三(酚)配体双功能稀土金属配合物，催化环氧化合物与CO₂的环加成反应。相关研究成果发表在2024年3月15日出版的国际学术期刊《中国化学》。

研究人员合成并表征了八种由带有季铵侧臂的氨基桥接三（酚）配体稳定的两性离子稀土金属配合物。这些配合物被用作CO₂和环氧化物环加成的单组分催化剂，其催化活性明显高于其二元类似物。进一步的研究表明，卤化物阴离子（Cl^–、Br^–、I^–）和金属络合物影响了催化活性，而含有碘化物阴离子的镧络合物对该加成反应表现出最高的催化活性。

在30°C和1 bar CO₂下，各种单取代环氧化物以良好至优异的产率（55%-99%）和高选择性（>99%）转化为环状碳酸酯，而内部环氧化物需要更高的反应温度（60-120°C）和催化剂负载量（2 mol%）才能获得高产率。该催化剂可循环使用四次，没有明显的催化活性损失。基于动力学研究和原位红外反应的结果，研究人员提出了一种合理的反应机理。

附：英文原文

Title: Cycloaddition Reactions of Epoxides and CO2 Catalyzed by Bifunctional Rare-Earth Metal Complexes Bearing Amino-Bridged Tris(phenolato) Ligands

Author: Yongjie Chen, Yanwei Wang, Jun Nong, Dan Yuan, Yingming Yao

Issue&Volume: 2024-03-15

Abstract: Eight zwitterionic rare earth metal complexes stabilized by amino-bridged tris(phenolato) ligands bearing quaternary ammonium side-arms were synthesized and characterized. These complexes were used as single-component catalysts for the cycloaddition of CO2 and epoxides, and their catalytic activities are obviously higher than those of their binary analogues. Further studies revealed that the halide anions (Cl–, Br–, I–) and the metal complexes influenced the catalytic activity, and the lanthanum complex bearing iodide anion showed the highest catalytic activity for this addition reaction. A variety of mono-substituted epoxides were converted to cyclic carbonates in good to excellent yields (55%—99%) with high selectivity (>99%) at 30 °C and 1 bar CO2, whereas internal epoxides required higher both reaction temperatures (60—120 °C) and catalyst loading (2 mol%) for high yields. The catalyst was recyclable for four times without noticeable loss of catalytic activity. Based on the results of kinetic studies and in situ IR reactions, a plausible reaction mechanism was proposed.

DOI: 10.1002/cjoc.202300753

Source: https://onlinelibrary.wiley.com/doi/full/10.1002/cjoc.202300753