1 Answers
Ge dicationic complexes refer to coordination compounds of germanium with a +2 formal oxidation state, and a +2 charge on the overall complex. In some of these coordination complexes, the coordination is strongly ionic, localizing a +2 charge on Ge, while in others the bonding is more covalent, delocalizing the cationic charge away from Ge. Examples of dicationic Ge complexes are much rarer than monocationic Ge complexes, often requiring the use of bulky ligands to shield the germanium center. Dicationic complexes of Ge have been isolated with bulky isocyanide and carbene ligands. Much more weakly coordinated Germanium dications have been isolated as complexes with polyether ligands, such as crown ethers and cryptand. Crown ethers and cryptands are typically known for their ability to bind metal cations, however these ligands have also been employed in stabilizing low-valent cations of heavier p-block elements. A Ge ion's valence shell consists of a filled valence s orbital but empty valence p orbitals, giving rise to atypical bonding in these complexes. Germanium is a metalloid of the carbon group, typically forming compounds with mainly covalent bonding, contrasting with the dative bonding observed in these coordination complexes.