PMo12O403

PMo12O403, commonly written as PMo12O40^3−, refers to the phosphomolydate polyoxometalate, a Keggin-type anion with the formula [PMo12O40]^3−. It comprises a central phosphate tetrahedron (PO4) surrounded by twelve MoO6 octahedra, producing a highly symmetric inorganic cluster. In solution the anion is the conjugate base of phosphomolylic acid, H3PMo12O40, and forms with various countercations such as Na+, K+, or NH4+. It is typically generated by condensing molybdate and phosphate sources under controlled acidic conditions and can be isolated as different salts.

As a polyoxometalate, PMo12O40^3− exhibits notable redox chemistry and strong oxidizing ability in acidic media. Its robust Keggin framework confers thermal and chemical stability, enabling applications as a homogeneous catalyst and as a structural precursor for materials based on heteroatom-containing polyoxometalates. In catalysis, the PMo12O40^3− motif participates in oxidative transformations, including alcohol oxidations and related redox processes, and can function in conjunction with other oxidants such as hydrogen peroxide.

In analytical chemistry, phosphomolydate reagents are used for qualitative and quantitative assays of reducing agents and for colorimetric determinations of total antioxidant capacity, often via the phosphomolydate “yellow” to blue transition upon reduction. Safety considerations reflect the compound’s acidity and oxidative potential; appropriate handling, ventilation, and protective equipment are advised.

See also: polyoxometalates, Keggin structure, phosphomolybdic acid, phosphomolydate assays.