Wang Qin, Abella Laura, Yao Yang-Rong, Yan Yingjing, Torrens Daniel, Meng Qingyu, Yang Shangfeng, Poblet Josep M, Rodríguez-Fortea Antonio, Chen Ning
College of Chemistry, Chemical Engineering and Materials Science, and State Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou 215123, Jiangsu, P. R. China.
Departament de Química Física i Inorgànica, Universitat Rovira i Virgili, Marcel·lí Domingo 1, 43007 Tarragona, Spain.
Inorg Chem. 2023 Aug 14;62(32):12976-12988. doi: 10.1021/acs.inorgchem.3c01764. Epub 2023 Aug 1.
Actinide endohedral metallofullerenes (EMFs) are a fullerene family that possess unique actinide-carbon cage host-guest molecular and electronic structures. In this work, a novel actinide EMF, U@(4)-C, was successfully synthesized and characterized, and its chemical reactivity was investigated. Crystallographic analysis shows that U@(4)-C, a new isomer of U@C, has a (4)-C cage, which has never been discovered in the form of empty or endohedral fullerenes. Its unique chemical reactivities were further revealed through the Bingel-Hirsch reaction and carbene addition reaction studies. The Bingel-Hirsch reaction of U@(4)-C shows exceptionally high selectivity and product yield, yielding only one major addition adduct. Moreover, the addition sites for both reactions are unexpectedly located on adjacent carbon atoms far away from the actinide metal, despite the nucleophilic (Bingel-Hirsch) and electrophilic (carbene addition) nature of either reactant. Density functional theory (DFT) calculations suggest that this chemical behavior, unprecedented for EMFs, is directed by the unusually strong interaction between U and the sumanene motif of the carbon cage in U@(4)-C, which makes the energy increase when it is disrupted. This work reveals remarkable chemical properties of actinide EMFs originating from their unique electronic structures and highlights the key role of actinide-cage interactions in the determination of their chemical behaviors.
锕系内嵌金属富勒烯（EMFs）是一类富勒烯家族，具有独特的锕系 - 碳笼主客体分子结构和电子结构。在本工作中，成功合成并表征了一种新型锕系EMF，U@(4)-C，并对其化学反应活性进行了研究。晶体学分析表明，U@(4)-C是U@C的一种新异构体，具有(4)-C笼结构，这种结构从未以空笼或内嵌富勒烯的形式被发现。通过Bingel-Hirsch反应和卡宾加成反应研究进一步揭示了其独特的化学反应活性。U@(4)-C的Bingel-Hirsch反应显示出极高的选择性和产物产率，仅生成一种主要的加成加合物。此外，尽管两种反应的反应物分别具有亲核性（Bingel-Hirsch反应）和亲电性（卡宾加成反应），但两种反应的加成位点都意外地位于远离锕系金属的相邻碳原子上。密度泛函理论（DFT）计算表明，这种对于EMFs来说前所未有的化学行为是由U与U@(4)-C中碳笼的sumanene基序之间异常强烈的相互作用所主导的，这种相互作用在被破坏时会使能量增加。这项工作揭示了源于其独特电子结构的锕系EMFs的显著化学性质，并突出了锕系 - 碳笼相互作用在决定其化学行为中的关键作用。
