Tetrahedral [HnPt4(CO)4(P∧P)2]n+(n= 1, 2; P∧P = CH2═C(PPh2)2) Cationic Mono- and Dihydrido Carbonyl Clusters Obtained by Protonation of the Neutral Pt4(CO)4(P∧P)2

The reaction of [Pt12(CO)24]2– with CH2═C(PPh2)2 (PP) results in the neutral tetrahedral cluster Pt4(CO)4(PP)2. This reacts with strong acids such as HBF4 to afford, first, the [HPt4(CO)4(PP)2]+ monohydride monocation and, then, the [H2Pt4(CO)4(PP)2]2+ dihydride dication. The three clusters have been fully characterized in solution by means of IR and 1H and 31P NMR spectroscopy. Both Pt4(CO)4(PP)2 and [H2Pt4(CO)4(PP)2]2+ are static in solution, whereas [HPt4(CO)4(PP)2]+ displays a fluxional behavior of the unique hydride ligand. In addition, the molecular structures of all these clusters have been fully determined in the solid state via single-crystal X-ray diffraction, showing that all of them possess the same 56-electron tetrahedral Pt4(CO)4(PP)2 core to which the hydride ligands are added stepwise.