Host-Guest Chemistry in Discrete Polyoxo-12-Palladate(II) Cubes [MO 8 Pd 12 L 8 ] n - (M = Sc III , Co II , Cu II , L = AsO 4 3 - ; M = Cd II , Hg II , L = PhAsO 3 2- ): Structure, Magnetism, and Catalytic Hydrogenation.

A family of five host-guest assemblies comprising different metal ions inside a cuboid 12-palladium-oxo cage, [MO 8 Pd 12 L 8 ] n - ( MPd 12 L 8 , M = Sc III , Co II , Cu II , L = AsO 4 3- ; M = Cd II , Hg II , L = PhAsO 3 2- ), was synthesized and structurally characterized in the solid state by single-crystal X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and thermogravimetric analysis, and their solution and gas-phase stability were validated by multinuclear NMR spectroscopy and electrospray-ionization mass spectrometry (ESI-MS). The polyoxopalladates (POPs) ScPd 12 As 8 , CoPd 12 As 8 , and CuPd 12 As 8 represent the first three examples of the MPd 12 As 8 archetype. The unique cubic ligand field of {MO 8 } allows for collecting the speciation profiles of the POPs in solution using 45 Sc and 113 Cd NMR techniques. Detailed magnetic and electron paramagnetic resonance (EPR) studies were performed on CuPd 12 As 8 . Catalytic studies on MPd 12 As 8 (M = Cu II and Co II ) supported on SBA-15 unveiled a guest metal-dependent structure-function relationship, with CuPd 12 As 8 being the more efficient precatalyst for the hydroconversion of o -xylene in a fixed-bed reactor.