Theoretical Study on the Ground State Structure of Uranofullerene U@C82

Despite its experimental characterization, the detailed geometry and electronic structure of actinide metallofullerene U@C82 have been rarely studied. We predict that #5C82 and #8C82 are the best cages for the encapsulation of monovalent and tetravalent U (i.e., U+ and U4+), respectively; while #9C82 is the best cage for divalent, trivalent, pentavalent, and hexavalent U cations (i.e., U2+, U3+, U5+, and U6+). U@#9C82 is the thermodynamically most stable one among all the isomers and thus corresponds to the most experimentally isolable isomer of U@C82. The calculated spin density explicitly suggests that the endohedral metallofullerene U@#9C82 is a trivalent ion-pair with an electronic configuration of U3+@C823–. The proposed geometry and electronic structure of U3+@#9C823– are in good agreement with the experimental observation.