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Ammonium tetrathiomolybdate is the chemical compound with the formula [NH4]2[MoS4]. This bright red ammonium salt is an important reagent in the chemistry of molybdenum and has been used as a building block in bioinorganic chemistry. The thiometallate anion has the distinctive property of undergoing oxidation at the sulfur centers concomitant with reduction of the metal from Mo(VI) to Mo(IV).
Additional recommended knowledge
Preparation and structure
The salt contains the tetrahedral [MoS4]2- anion. The compound is prepared by treating solutions of molybdate, [MoO4]2- with hydrogen sulfide in the presence of ammonia:
The anion is also an excellent ligand. For example, with Ni(II) sources, it forms [Ni(MoS4)2]2-. Much of the chemistry of the thiomolybdate results from studies on salts of quaternised organic cations, such as [NEt4]2[MoS4] and [PPh4]2[MoS4] (Et = C2H5, Ph = C6H5). These organic salts are soluble in polar organic solvents such as acetonitrile and dmf.
The thermal decomposition of [NH4]2[MoS4] leads to sulphides of composition MoSx (2< x< 3), which are of interest as catalysts for hydrodesulfurization.
Several related thio and seleno anions are known including (A = alkali metal cation, [PPh4]+, [NEt4]+)
More complex tetrahedral anions include A2[MoS4-xOx] and A2[WS4-xOx]
Categories: Molybdenum compounds | Sulfides | Ammonium compounds
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Ammonium_tetrathiomolybdate". A list of authors is available in Wikipedia.|