Bis(germavinylidene) [(Me3SiN=PPh2)2C=Ge→Ge=C(Ph2P=NSiMe3)] and 1,3‐Dimetallacyclobutanes [M{μ2‐C(Ph2P=NSiMe3)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(Ph2 P=NSiMe3 )2 Li(thf)] and GeCl2 ⋅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.