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

Inspired by the experimentally synthesized Na @[(UO )(O ) ] ("Na @U ") cluster, we have explored computationally the substitution of the Na cations by many other metals. 6 other M @U systems are found to be stable (M=K , Rb , Cs , Ag , Mg , Fe ). For 3 of these (Mg , 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 @U (E=S , Se , Te , and Po ). These systems have 3-shell, onion-like geometries with nearly perfect I symmetry. Seeking to create clusters with very high spin ground states, we have replaced M by Mn and U by Np and Pu , generating clusters with maximum possible S values of 80/2 and 100/2 respectively. Only in the presence of a central S , however, are these electronic configurations the most stable; the novel Matryoshka Pu nanocluster S@Mn @Pu is predicted to have the highest ground state spin yet reported for a molecular cluster.