In chemistry a tungstate is a compound that contains an oxoanion of tungsten or is a mixed oxide containing tungsten. The simplest tungstate ion is WO42−, "orthotungstate". There are many other tungstate ions that contain more than one tungsten atom and belong to a large group of polyatomic ions that are termed polyoxometalates, ("POMs"), and specifically termed isopolyoxometalates as they contain, along with oxygen and maybe hydrogen, only one other element. Comparing tungsten to the other group 6 elements, the large tungstate ions generally contain 6 coordinate metal atoms similar to molybdenum (molybdates) and contrast to chromium (chromates) where 4 coordination predominates.
Some examples of tungstate ions that have been detected in solution in the solid state include:< HWO4−
polymeric W2O72− ions of various structures in Na2W2O7, Li2W2O7 and Ag2W2O7
[W7O24]6− (paratungstate A)
[W10O32]4− (tungstate Y)
[H2W12O42]10− (paratungstate B)
β-[H2W12O40]6− (tungstate X)