Synthesis of Silicon and Germanium-Containing Heterosumanenes via Rhodium-Catalyzed Cyclodehydrogenation of Silicon/Germanium–Hydrogen and Carbon–Hydrogen Bonds

A three-step synthesis
of C3-symmetric
trisilasumanene and trigermasumanene, heteroanalogues of the π-bowl
sumanene, was achieved using a threefold rhodium-catalyzed cyclodehydrogenation
of Si/Ge–H and C–H bonds as the key step. Trigermasumanene
was proven to adopt a planar geometry by single crystal X-ray diffraction
for the first time. The optical properties were also investigated
by UV–vis and fluorescence spectroscopy.