UCN@<i>C</i><sub><i>s</i></sub>(6)-C<sub>82</sub>: An Encapsulated Triangular UCN Cluster with Ambiguous U Oxidation State [U(III) versus U(I)]
Qingyu Meng, Laura Abella, Wei Yang, Yang‐Rong Yao, Xinye Liu, Jiaxin Zhuang, Xiaomeng Li, Luís Echegoyen, Jochen Autschbach, Ning Chen
Abstract
Understanding the chemical behavior of actinide elements is essential for the effective management and use of actinide materials. In this study, we report an unprecedented η2 (side-on) coordination of U by a cyanide in a UCN cluster, which was stabilized inside a C82 fullerene cage. UCN@Cs(6)-C82 was successfully synthesized and fully characterized by mass spectrometry, single crystal X-ray crystallography, cyclic voltammetry, spectroscopy, and theoretical calculations. The bonding analysis demonstrates significant donation bonding between CN– and uranium, and covalent interactions between uranium and the carbon cage. These effects correlate with an observed elongated cyanide C–N bond, resulting in a rare case where the oxidation state of uranium shows ambiguity between U(III) and U(I). The discovery of this unprecedented triangular configuration of the uranium cyanide cluster provides a new insight in coordination chemistry and highlights the large variety of bonding situations that uranium can have.