A High Yield Synthesis of an Octastannacubane and a Bis(silyl) Stannylene via Reductive Elimination of a Silane

Thermolysis of tris(silyl) tin hydride 2 at 70 °C for 3 hours results in elimination of tBu₂MeSiH and generation of bis(silyl) stannylene 3 which dimerizes instantaneously yielding distannene 4. Compound 3 can be trapped by NHC^Me yielding stannylene-NHC^Me complex 5. Upon heating (70 °C, 24 h) 4 yields stannyl radical 8 along with pentastannatricyclo[2.1.0.0^{2, 5}]pentane 10 (ca. 30 %) and traces (ca. 5 %) of the novel octastannacubane 9. Remarkably, octastannacubane 9 is produced in 70 % yield by mild heating (50 °C) of 1,1,2,2-tetrasilyldistannane 11, along with tBu₂MeSiH. Octastannacubane 9 was characterized by X-ray crystallography, NMR and UV/Vis spectroscopy. Based on DFT quantum-mechanical calculations the 11 → 9 transformation occurs via reductive elimination of two tBu₂MeSiH molecules from 11 yielding a distannyne, (or its bis-stannylene isomer), followed by its tetramerization.