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, solid ammonium dimolybdate decomposes to molybdenum trioxide:^[1]

Ammonium dimolybdate

Names
Other names ADM
Identifiers
CAS Number	27546-07-2
3D model (JSmol)	Interactive image
ECHA InfoCard	100.044.092
PubChem CID	21895884
CompTox Dashboard (EPA)	DTXSID7094399
InChI InChI=1S/2Mo.H3N.8O/h;;1H3;;;;;;;;/q;;;;;;;4*-1/p+1 Key: UHQWHVHZVHVJFE-UHFFFAOYSA-O
SMILES [NH4+].[O-][Mo](=O)(=O)O[Mo](=O)(=O)[O-].[NH4+]
Properties
Chemical formula	H8N2Mo2O7
Appearance	white solid
Density	2.97 g/cm3
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

(NH₄)₂Mo₂O₇ → 2 MoO₃ + 2 NH₃ + H₂O

In terms of its chemical structure, the anion is a polymeric consisting of distorted octahedral Mo centers linked by tetrahedral molybdate centers.^[2] When prepared in the absence of water as its tetrabutylammonium salt, dimolybdate adopts the centrosymmetric structure observed for dichromate.^[3]