Doubly Bonded Derivatives of Germanium

Publisher Summary This chapter discusses the synthesis, physical properties, and reactivity of doubly bonded germanium species. The >Ge=M' derivatives (M' = group 14, 15, or 16 elements) are reviewed. The several species discussed are germens (>Ge=C Ge=Ge Ge=Si Ge=Sn Ge=N––), germaphosphenes (>Ge=P––), germanones (>Ge=O), germanethiones (>Ge=S), and germaallenes (>Ge=C=X). The new routes to such doubly bonded derivatives, their physical data together with theoretical calculations and their reactivity are discussed and the doubly bonded compounds between germanium and main group elements are described. Calculations performed on H2CGe (H2C= Ge:, H2Ge = C:, and HGe ≡ CH) predict that the trans-bent germyne isomer requires 7 kcal/ mol to isomerize to the germavinylidene isomer. In contrast to the double-bond derivatives of germanium, the triply bonded derivatives of group 14 elements -M=X (X = C, M, N, P) are still unknown, even though it seems possible, using convenient groups, to stabilize such species.