Polymolybdates

Polymolybdates are a class of inorganic compounds containing multiple molybdenum atoms linked by shared oxygen atoms. These complex anions are formed in aqueous solutions of molybdate salts when the pH is lowered or the concentration of molybdate ions is increased. The specific structure of a polymolybdate depends on factors such as the pH, concentration, and the presence of other cations. Common examples include paramolybdates, which have a tetrahedral structure, and isopolymolybdates, where only molybdenum and oxygen atoms are present. Heteropolymolybdates also exist, incorporating other heteroatoms like phosphorus or silicon into their structures.

The formation of polymolybdates is a reversible process. As the pH of a molybdate solution decreases, smaller molybdate species condense to form larger polymolybdate anions. Conversely, increasing the pH leads to the breakdown of polymolybdates back into simple molybdate ions. This pH-dependent speciation is a key characteristic of molybdenum chemistry in aqueous solutions. Polymolybdates have found applications in various fields, including catalysis, analytical chemistry, and as precursors for the synthesis of advanced materials. Their diverse structures and reactivity make them interesting subjects of study in inorganic and coordination chemistry.