Sodium decavanadate

Content sourced from Wikipedia, licensed under CC BY-SA 3.0.

Sodium decavanadate is the sodium salt Na6[V10O28](H2O)n of the decavanadate ion [V10O28]6−. It is an orange solid.

The decavanadate ion is made of ten VO6 octahedra linked together, with vanadium in the +5 oxidation state. This ion can form salts with various cations; in sodium decavanadate, six sodium ions balance the charge.

Preparation and stability:
- It is typically formed by acidifying an aqueous solution of orthovanadate (VO4^3−).
- The best formation occurs at a pH around 4–7. Other vanadate species, such as metavanadate and hexavanadate, can appear depending on the pH.

In solution and structure:
- The decavanadate anion has three sets of equivalent vanadium atoms and a network of oxygen atoms. The crystal form Na6[V10O28]·18H2O has been confirmed by X-ray studies.
- The vanadium in this compound remains +5.

Color and pH behavior:
- Solutions around pH 6.5 turn bright orange, indicating the presence of decavanadate. At very low pH (below about 2), brown hydrated V2O5 tends to precipitate.

Biological notes:
- Decavanadate can inhibit the enzyme phosphoglycerate mutase, involved in glycolysis.
- It has shown modest activity against the parasite Leishmania tarentolae, suggesting potential topical anti-parasite uses.

Other decavanadate salts:
- Many others exist, including ammonium, calcium, barium, strontium, and other group I salts, formed by reacting V2O5 with the corresponding base.