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 II 6 O 12 M 8 {(CH 3 ) 2 AsO 2 } 16 (H 2 O) 8 ] 4+ (M=Ce IV , Th IV ), 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 6 O 12 } 12- core that is capped by eight M IV ions, resulting in a cationic, cubic assembly {Pd 6 O 12 M IV 8 } 20+ , which is coordinated by a total of 16 terminal dimethylarsinate and eight water ligands, resulting in the mixed Pd II -Ce IV /Th IV oxo-clusters [Pd II 6 O 12 M 8 {(CH 3 ) 2 AsO 2 } 16 (H 2 O) 8 ] 4+ (M=Ce, Pd 6 Ce 8 ; Th, Pd 6 Th 8 ). We have also studied the formation of host-guest inclusion complexes of Pd 6 Ce 8 and Pd 6 Th 8 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 2 -reduction and HCOOH-oxidation.