Discrete, Cationic Palladium(II)-Oxo Clusters via f-Metal Ion Incorporation and their Macrocyclic Host-Guest Interactions with Sulfonatocalixarenes.

We report on the discovery of the first two examples of cationic palladium(II)-oxo clusters (POCs) containing f-metal ions, [Pd O M {(CH ) AsO } (H O) ] (M=Ce , Th ), and their physicochemical characterization in the solid state, in solution and in the gas phase. The molecular structure of the two novel POCs comprises an octahedral {Pd O } core that is capped by eight M ions, resulting in a cationic, cubic assembly {Pd O M } , which is coordinated by a total of 16 terminal dimethylarsinate and eight water ligands, resulting in the mixed Pd -Ce /Th oxo-clusters [Pd O M {(CH ) AsO } (H O) ] (M=Ce, Pd Ce ; Th, Pd Th ). We have also studied the formation of host-guest inclusion complexes of Pd Ce and Pd Th with anionic 4-sulfocalix[n]arenes (n=4, 6, 8), resulting in the first examples of discrete, enthalpically-driven supramolecular assemblies between large metal-oxo clusters and calixarene-based macrocycles. The POCs were also found to be useful as pre-catalysts for electrocatalytic CO -reduction and HCOOH-oxidation.