A Zwitterionic Phosphonium Stannate(II) via Hydrogen Splitting by a Sn/P Frustrated Lewis-Pair and Reductive Elimination

The reactivity of the frustrated Lewis pair (FLP) (F5C2)(3)SnCH2P(tBu)(2) (1) was investigated with respect to the activation of elemental hydrogen. The reaction of 1 at elevated hydrogen pressure afforded the intramolecular phosphonium stannate(II) (F5C2)(2)SnCH2PH(tBu)(2) (3). It was characterized by means of multinuclear NMR spectroscopy and single crystal X-ray diffraction. NMR experiments with the two isotopologues H-2 and D-2 showed it to be formed via an H-2 adduct (F5C2)(3)HSnCH2PH(tBu)(2) (2) and the subsequent formal reductive elimination of pentafluoroethane; this is supported by DFT calculations. Parahydrogen-induced polarization experiments revealed the formation of a second product of the reaction of 1 with H-2, [HP(tBu)(2)Me][Sn(C2F5)(3)] (4), in H-1 NMR spectra, whereas 2 was not detected due to its transient nature.