Synthesis of octastannacubane from silyl-substituted tin hydrides

Recently we found that intermediate bis-silyl stannylene (2) can be conveniently generated under relatively mild conditions (70°C) from trisilyl - substituted tin hydride (1) (Scheme, step a). Stannylene 2 dimerizes instantaneously yielding the distannene (3) (Scheme, step b). When 2 is generated in the presence of NHC^Me, it is quantitatively converted to the stable stannylene-carbene complex (4) (Scheme, step c).

Heating of distannene 3 at 70°C for 24 hours yields the known stable stannyl radical (5) and surprisingly also the novel octastannacubane (6) in 5% yield (Scheme, step d). Remarkbly, octastannacubane 6 can be also produced in much higher yield (70%), in a one-pot reaction, by mild heating (50⁰C) of silyl – substituted tin dihydride (7) with elimination of silane as a coproduct (Scheme, step e).