Bis(germavinylidene) [(Me 3 SiN=PPh 2 ) 2 C=Ge→Ge=C(Ph 2 P=NSiMe 3 )] and 1,3‐Dimetallacyclobutanes [M{ μ 2 ‐C(Ph 2 P=NSiMe 3 ) 2 }] 2 (M=Sn, Pb)

Low‐valent metallavinylidenes :M=C/\ are scarce owing to the low stability of such species. Compound 1 , prepared from [CH(Ph 2 P=NSiMe 3 ) 2 Li(thf)] and GeCl 2 ⋅dioxane, represents the first stable bis(germavinylidene). The dimetallacyclobutanes 2 (M=Pb, Sn) were also prepared—they are believed to form by dimerization of the intermediate metallavinylidenes.