Tetramolybdates

Tetramolybdates are a class of chemical compounds containing the tetramolybdate anion, which has the formula [Mo4O12(OH)2]2− or related structures. These polyoxometalate anions are characterized by a cluster of four molybdenum atoms. Tetramolybdates are typically formed in aqueous solutions of molybdenum(VI) oxides under specific pH conditions, often in the neutral to slightly acidic range. As the pH decreases, more condensed forms of molybdates, including tetramolybdates, tend to precipitate.

The structure of the tetramolybdate anion is complex and can exist in various isomeric forms. A common form features a ring-like structure where the four molybdenum atoms are bridged by oxygen atoms. The presence of hydroxyl groups or water molecules coordinated to the molybdenum centers is also typical. Tetramolybdates are often encountered as salts with alkali metal cations, such as sodium or potassium. Their solubility in water varies depending on the counterion.

These compounds have found applications in several areas. They can act as precursors for the synthesis of other molybdenum-containing materials, including catalysts. In analytical chemistry, tetramolybdates have been used as reagents for the determination of certain substances. Their ability to form complexes with other species also makes them of interest in coordination chemistry research. Understanding the formation and structure of tetramolybdates is crucial for controlling the properties of molybdenum-based materials and processes.