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

• Published in: Chemistry : a European journal 2020-12, Vol.26 (72), p.17381-17385
• Main Authors: Holtkamp, Philipp, Schwabedissen, Jan, Neumann, Beate, Stammler, Hans‐Georg, Koptyug, Igor V., Zhivonitko, Vladimir V., Mitzel, Norbert W.
• Format: Article
• Language: English
• Subjects: activation; Chemistry; Communication; Communications; fluoroalkyl groups; frustrated Lewis pair; Hydrogen; Induced polarization; Magnetic resonance spectroscopy; NMR; NMR spectroscopy; Nuclear magnetic resonance; Pentafluoroethane; Single crystals; Spectrum analysis; tin; Zwitterions
• ISSN: 0947-6539; 1521-3765; 1521-3765
• DOI: 10.1002/chem.202004425

The reactivity of the frustrated Lewis pair (FLP) (F5C2)3SnCH2P(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)2SnCH2PH(tBu)2 (3). It was characterized by means of multinuclear NMR spectroscopy and single crystal X‐ray diffraction. NMR experiments with the two isotopologues H2 and D2 showed it to be formed via an H2 adduct (F5C2)3HSnCH2PH(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 H2, [HP(tBu)2Me][Sn(C2F5)3] (4), in 1H NMR spectra, whereas 2 was not detected due to its transient nature. Hydrogen splitting and two pathways of reductive elimination were found by reacting H2 with an intramolecular Sn/P frustrated Lewis pair; quantum‐chemical calculations and high‐pressure NMR experiments indicate an neutral and zwitterionic phosphonium stannate(II) as the energetically favored product of reaction.