Self-assembly of hexanuclear clusters of 4f and 5f elements with cation specificity

摘要

Six hexanuclear clusters of 4f and 5f elements were synthesized by room-temperature slow concentration experiments. Cerium(IV), thorium(IV), and plutonium(IV) each form two different hexanuclear clusters, among which the cerium and plutonium clusters are isotypic, whereas the thorium clusters show more diversity. The change in ionic radii of approximately 0.08 ? between these different metal ions tunes the cavity size so that NH_4~+ (1.48 ?) has the right dimensions to assemble the cerium and plutonium clusters, whereas Cs~+ (1.69 ?) is necessary to assemble the thorium clusters. If these cations are not used in the reactions, only amorphous material is obtained.