divanadate

Divanadate refers to the divanadate anion, commonly written as [V2O7]4−, a condensation product of two vanadium(V) oxide tetrahedra. It is one of the fundamental polyvanadate species that appear in aqueous vanadate solutions under acidic conditions and during polymerization of vanadium oxide species. Structurally, the anion consists of two VO4 tetrahedra linked by a single shared edge through a bridging oxygen, giving a V–O–V connectivity. Each vanadium center remains coordinated to five oxygens, resulting in a relatively compact V2O7 core.

In solution, divanadate coexists with other polyvanadates such as metavanadate [VO3]− and larger species, with the distribution governed by pH and total vanadium concentration. The conjugate acid of divanadate is often described as divanadic acid, H2V2O7. The divanadate anion forms salts with various cations, and these salts are encountered in inorganic synthesis and studies of vanadium oxide chemistry. The stability of divanadate is favored at intermediate acidity; at higher pH, it tends to convert to other polyvanadate species, including larger oligomers, while strongly acidic conditions can lead to further hydrolysis andshift in equilibria.

Applications and relevance: divanadate species are of interest in the broader study of vanadium oxides, polyvanadates, and redox chemistry, where they serve as models for understanding condensation processes, acid-base behavior, and the structure–function relationships of vanadium-containing materials. They are also discussed in relation to metavanadate and decavanadate chemistry as part of the vanadium(V) oxide system. See also metavanadate, decavanadate, polyvanadates.