[LnO] Cluster-Encapsulating Polyplumbites as New Polyoxometalate Members and Record Inorganic Anion-Exchange Materials for ReO Sequestration.

Various types of polyoxometalates (POMs) have been synthesized since the 19th century, but their assortment has been mostly limited to Groups 5 and 6 metals. Herein, a new family of POMs composed of a carbon group element as the addenda atoms with two distinct phases, (Ln = Sm to Ho, Y) and (Ln = Er and Tm) is reported. Both structures are built from [LnO] rare-earth metal hexamers being incorporated in [PbO]/[PbO] polyplumbites, and unbound perchlorates as charge-balancing anions. Impressively, and exhibit exceptional uptake capacities (434.7 and 427.7 mg g) toward ReO , a chemical surrogate for the key radioactive fission product in the nuclear fuel cycle TcO , which are the highest values among all inorganic anion-exchange materials reported until now. The sorption mechanism is clearly elucidated and visualized by single-crystal-to-single-crystal structural transformation from to a perrhenate-containing complex , revealing a unique ReO uptake selectivity driven by specific interaction within Pb···O-ReO bonds.