Ammonium dimolybdate

Ammonium dimolybdate (ADM) is the inorganic compound with the formula (NH₄)₂Mo₂O₇. It is a white, water-soluble solid. ADM is an intermediate in the production of molybdenum compounds from its ores. Roasting typical ore produces crude molybdenum(VI) oxides, which can be extracted into aqueous ammonia, affording ammonium molybdate. Heating solutions of ammonium molybdate gives ADM. Upon heating the solid, ammonium dimolybdate decomposes to molybdenum trioxide:

In terms of its chemical structure, it is a polymeric consisting of distorted octahedral Mo centers liked by tetrahedral molybdate centers.