In chemistry a molybdate is a compound
containing an oxoanion with molybdenum in its highest oxidation state of 6.
Molybdenum can form a very large range of such oxoanions which can be
discrete structures or polymeric extended structures, although the latter
are only found in the solid state.The larger oxoanions are members of group
of compounds termed polyoxometalates, and because they contain only one type
of metal atom are often called isopolymetalates[1]. The discrete molybdenum
oxoanions range in size from the simplest MoO42-,
found in sodium molybdate up to extremely large structures found in
isopoly-molybdenum blues that contain for example 154 Mo atoms. The
behaviour of molybdenum is different from the other elements in group 6.
Chromium only forms the chromates, CrO42-, Cr2O72-,
Cr3O102- and Cr4O132-
ions which are all based on tetrahedral chromium. Tungsten is similar to
molybdenum and forms many tungstates containing 6 coordinate tungsten[2].
