Disilagermirenes: heavy cyclopropenes of Si and Ge atoms

Tetrakis[di-tert-butyl(methyl)silyl]-1-disilagermirene (3) was prepared by the reaction of 2,2,2-tribromo-1,1-di-tert-butyl-1-methyldisilane and dichlorobis[di-tert-butyl(methyl)silyl]germane with sodium in toluene. The molecular structure of 3 was established by X-ray crystallography, which showed a trans-bent configuration around the SiSi double bond with a bond length of 2.146(1) Å. Thermal and photochemical isomerization of 3 to tetrakis[di-tert-butyl(methyl)silyl]-2-disilagermirene (4) is also reported, as well as the reactions of 3 with MeI, PhCH2OH, and PhCOCH3.