Interconversion among Dianionic, Anionic, and Neutral Compounds Bearing a Bond between Two Pentacoordinated Germanium Atoms

The first dianionic compounds bearing a bond between two pentacoordinated germanium atoms have been synthesized in a stable form as candidates for a core unit to construct unprecedented structures in group 14 element chemistry. X-ray crystallographic analysis and computational study indicated the single-bond character of the Ge–Ge bond. They were reversibly converted to the anionic and neutral Ge–Ge-bonded compounds while maintaining the coordination number of the germanium atoms. The interconversion features changes in structures around the germanium atoms, including changes from a staggered conformation of the Ge–O bonds to a parallel conformation.