Polyoxomolybdates

Polyoxomolybdates are a large and diverse class of inorganic compounds containing discrete, negatively charged clusters of molybdenum-oxygen anions. These clusters are typically formed by the condensation of individual molybdate units, such as MoO4^2-. The structures of polyoxomolybdates are highly varied, ranging from simple dimeric and trimeric units to complex, cage-like architectures with well-defined cavities. The precise structure depends on factors such as the molybdenum-to-oxygen ratio, the presence of other metal ions (heteroatoms), and the pH of the solution during synthesis.

These compounds exhibit a rich coordination chemistry due to the ability of molybdenum to exist in various oxidation states, most commonly +5 and +6. The bonding within these clusters involves Mo-O bonds with significant covalent character, and the overall negative charge is balanced by countercations, typically alkali or alkaline earth metals, or sometimes organic cations. Polyoxomolybdates are often soluble in water and can be isolated as crystalline solids.

The structural diversity and tunable properties of polyoxomolybdates have led to extensive research into their potential applications. They are investigated for their catalytic activity, particularly in oxidation reactions, due to the redox versatility of molybdenum. Their ability to encapsulate guest molecules within their cavities has also led to studies in areas such as molecular recognition, sensing, and drug delivery. Furthermore, their unique electronic and optical properties are being explored for applications in materials science.