Characterization of a strong covalent Th3+–Th3+ bond inside an Ih(7)-C80 fullerene cage
Jiaxin Zhuang1,8, Roser Morales-Martínez2,8, Jiangwei Zhang 3,8, Yaofeng Wang1,8, Yang-Rong Yao4, Cuiying Pei5, Antonio Rodríguez-Fortea 2, Shuao Wang 6, Luis Echegoyen4, Coen de Graaf 2,7, Josep M. Poblet2* & Ning Chen 1*（谌宁）
1 College of Chemistry, Chemical Engineering and Materials Science, and State Key Laboratory of Radiation Medicine and Protection, Soochow University, Suzhou, Jiangsu, China.
2 Departament de Química Física i Inorganica, Universitat Rovira i Virgili, Tarragona, Spain.
3 State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences (CAS), Dalian, China.
4 Department of Chemistry, University of Texas at El Paso, El Paso, Texas, USA.
5 Center for High Pressure Science and Technology Advanced Research, Pudong District, Shanghai, China.
6 State Key Laboratory of Radiation Medicine and Protection, School for Radiological and Interdisciplinary Sciences (RAD-X), and Collaborative Innovation Center of Radiation Medicine of Jiangsu Higher Education Institutions, Soochow University, Suzhou, China.
7 ICREA, Pg Lluis Companys 23, Barcelona, Catalonia, Spain.
8 These authors contributed equally: Jiaxin Zhuang, Roser Morales-Martínez, Jiangwei Zhang, Yaofeng Wang.
NATURE COMMUNICATIONS , (2021) 12:2372
The nature of the actinide-actinide bonds is of fundamental importance to understand the electronic structure of the 5f elements. It has attracted considerable theoretical attention, but little is known experimentally as the synthesis of these chemical bonds remains extremely challenging. Herein, we report a strong covalent Th-Th bond formed between two rarely accessible Th3+ ions, stabilized inside a fullerene cage nanocontainer as Th2@Ih(7)-C80. This compound is synthesized using the arc-discharge method and fully characterized using several techniques. The single-crystal X-Ray diffraction analysis determines that the two Th atoms are separated by 3.816 Å. Both experimental and quantum-chemical results show that the two Th atoms have formal charges of +3 and confirm the presence of a strong covalent Th-Th bond inside Ih(7)-C80. Moreover, density functional theory and ab initio multireference calculations suggest that the overlap between the 7s/6d hybrid thorium orbitals is so large that the bond still exists at Th-Th separations larger than 6 Å. This work demonstrates the authenticity of covalent actinide metal-metal bonds in a stable compound and deepens our fundamental understanding of f element metal bonds