H4GeO4

H4GeO4, also known as germanic acid, is a hypothetical chemical compound. It represents the fully protonated form of the germanate anion, GeO4^4-. Germanium, in this compound, would be in its +4 oxidation state. While germanic acid itself has not been definitively isolated or characterized in a stable form, its theoretical existence is inferred from the chemistry of germanium oxides and hydroxides.

Germanium, being in the same group as silicon in the periodic table, exhibits similar chemical behavior, including the formation of acidic oxides. Germanium dioxide (GeO2) can react with water to form hydrated forms that are often referred to as germanic acid. These hydrated forms are typically polymeric and their exact structure is complex and depends on the conditions of formation. The empirical formula for these hydrated forms is often written as GeO2·nH2O, where n can vary.

The theoretical H4GeO4 molecule would involve a central germanium atom bonded to four hydroxyl (OH) groups. In aqueous solutions, germanic acid is expected to be a weak acid, capable of donating protons to form various germanate species. The precise acidity and the nature of these species in solution would be influenced by pH and concentration. Research into germanate chemistry primarily focuses on the more stable forms like germanium dioxide and its salts.