MOLYBDATE (VI) [99 MO]

Inchemistry, amolybdateis a compound containing anoxyanionwithmolybdenumin its highestoxidation stateof +6:O−−Mo(=O)2−O−. Molybdenum can form a very large range of suchoxyanions, which can be discrete structures orpolymericextended structures, although the latter are only found in thesolidstate. The larger oxyanions are members of group of compounds termedpolyoxometalates, and because they contain only one type of metal atom are often calledisopolymetalates.The discrete molybdenum oxyanions range in size from the simplestMoO2−4, found in potassium molybdate up to extremely large structures found inisopoly-molybdenum bluesthat contain for example 154 Mo atoms. The behaviour of molybdenum is different from the other elements ingroup 6.Chromiumonly forms thechromates,CrO2−4,Cr2O2−7,Cr3O2−10andCr4O2−13ions which are all based on tetrahedral chromium.Tungstenis similar to molybdenum and forms manytungstatescontaining 6 coordinate tungsten.