High Spin Ground States in Matryoshka Actinide Nanoclusters: A Computational Study

Inspired by the experimentally synthesized Na 12 @[(UO 2 )(O 2 ) 1.5 ] 20 8− (“Na 12 @U 20 ”) cluster, we have explored computationally the substitution of the Na cations by many other metals. 6 other M 12 @U 20 systems are found to be stable ( M =K + , Rb + , Cs + , Ag + , Mg 2+ , Fe 2+ ). For 3 of these (Mg 2+ , Ag + and Na + ), the cluster can support a group 16 dianion at its center, forming a new type of Matryoshka (“Russian Doll”) actinide nanocluster E @ M 12 @U 20 (E=S 2− , Se 2− , Te 2− , and Po 2− ). These systems have 3‐shell, onion‐like geometries with nearly perfect I h symmetry. Seeking to create clusters with very high spin ground states, we have replaced M by Mn 2+ and U 20 by Np 20 and Pu 20 , generating clusters with maximum possible S values of 80/2 and 100/2 respectively. Only in the presence of a central S 2− , however, are these electronic configurations the most stable; the novel Matryoshka Pu nanocluster S@Mn 12 @Pu 20 is predicted to have the highest ground state spin yet reported for a molecular cluster.