A Chemical Trick: How To Make a Digermene from a Disilene, Formation of 3Δ-1,2,3,4-Disiladigermetene

The unexpected reaction of tetrakis[di-tert-butyl(methyl)silyl]disilagermirenes (1a and 1b) with GeCl2.dioxane results in the quantitative formation of trans-1,2-dichloro-1,2,3,4-tetrakis[di-tert-butyl(methyl)silyl]-3Delta-1,2,3,4-disiladigermetene, 2, representing the first cyclotetrametallene containing two different heavier group 14 elements and the first digermene incorporated in a four-membered ring. trans-1,2-Dichloro-1,2,3,4-tetrakis[di-tert-butyl(methyl)silyl]-3Delta-1,2,3,4-disilagermastannetene (8), with a Ge=Sn double bond, was also prepared by the reaction of 1 with SnCl2.dioxane. The crystal structure of 2 was established by X-ray crystallography, which showed a folded four-membered ring skeleton with a long Ge=Ge double bond (2.2911(4) A). The structural peculiarities of 2, as well as the possible mechanism of its formation, are also discussed.