Tetrahedral [H_nPt_4(CO)_4(P~ ?P)_2]~(n+) (n = 1, 2; P?P = CH_2=C(PPh_2)_2) cationic mono- and dihydrido carbonyl clusters obtained by protonation of the neutral Pt_4(CO) _4(P?P)_2

摘要

The reaction of [Pt_(12)(CO)_(24)]~(2-) with CH_2=C(PPh_2)_2 (P?P) results in the neutral tetrahedral cluster Pt_4(CO)_4(P~ ?P)_2. This reacts with strong acids such as HBF_4 to afford, first, the [HPt_4(CO)_4(P~ ?P)_2]~+ monohydride monocation and, then, the [H_2Pt_4(CO)_4(P?P) _2]~(2+) dihydride dication. The three clusters have been fully characterized in solution by means of IR and 1H and 31P NMR spectroscopy. Both Pt_4(CO)_4(P~ ?P)_2 and [H_2Pt_4(CO) _4(P?P)_2]~(2+) are static in solution, whereas [HPt_4(CO)_4(P?P) _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 Pt _4(CO)_4(P?P)_2 core to which the hydride ligands are added stepwise.