Small-molecule Activation by Low-coordinated Germanium Compounds

We have been interested in the differences of properties between low-coordinated carbon compounds and their heavier homologues of group 14 based on e.g., Si and Ge. Fundamental research on the synthesis and characterization of divalent and multiple-bond compounds of heavier group-14 elements has led to a variety of isolated low-coordinated species of heavier group-14 elements that can serve in small-molecule transformations instead of transition metals. The author and his co-workers have focused especially on low-coordinated germanium compounds with double or triple bonds between germanium atoms, and germanium-containing aromatic compounds. Once isolated, the reactivity of these low-coordinated germanium compounds was examined with regard to small-molecule activation. In this account, the reactivity patterns of these compounds will be described.