Pt IV -Containing Hexaplatinate(II) [Pt IV Pt II 6 O 6 (AsO 2 (CH 3 ) 2 ) 6 ] 2- and Hexapalladate(II) [Pt IV Pd II 6 O 6 (AsO 2 (CH 3 ) 2 ) 6 ] 2 .

The first Pt IV -containing discrete polyoxoplatinate(II) [Pt IV Pt II 6 O 6 (AsO 2 (CH 3 ) 2 ) 6 ] 2- ( Pt 7 ) and polyoxopalladate(II) [Pt IV Pd II 6 O 6 (AsO 2 (CH 3 ) 2 ) 6 ] 2- ( PtPd 6 ) have been prepared and characterized in the solid state, in solution, and in the gas phase. The molecular structures of the noble metal-oxo clusters Pt 7 and PtPd 6 comprise a central, octahedral Pt IV O 6 hetero group surrounded by six square-planar MO 4 (M = Pt II , Pd II ) units, which are capped by six dimethylarsinate ligands. The polyanions were prepared under simple one-pot aqueous solution conditions by reacting H 2 Pt(OH) 6 with either K 2 PtCl 4 or Pd(NO 3 ) 2 in sodium dimethylarsinate buffer (pH 7) at 80 °C. Catalytic studies were performed on Pt 7 supported on SBA15-apts for o -xylene hydrogenation at 300 °C and 90 bar H 2 pressure and indicated excellent activity and recyclability with low activation temperature.