|Jmol-3D images||Image 1|
|Molar mass||260.28 g/mol|
|Melting point||decomp ~ 155 °C|
|Crystal structure||B. Hill, H.-W. Lerner and M. Bolte (2010). Acta Crystallographica E 66 (13). doi:10.1107/S1600536810003016.|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Ammonium tetrathiomolybdate is the chemical compound with the formula [NH4]2MoS4. 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).
Preparation and structure
- [NH4]2[MoO4] + 4 H2S → [NH4]2[MoS4] + 4 H2O
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.
- (NH4)2(MoS4) → MoS3 + 2 NH3 + H2S
MoS3 then decomposes again to molybdenum disulfide (MoS2) in a broad temperature range from 300 °C to 820 °C. Perfect decomposition to MoS2 under inert gas requires at least 800 °C according to the following reaction,
- MoS3 → MoS2 + S
but it can also be achieved at 450 °C, if there is enough hydrogen.
- MoS3 + H2 → MoS2 + H2S
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]
Ammonium tetrathiomolybdate was first used therapeutically in the treatment of copper toxicosis in animals. It was then introduced as a treatment in Wilson's disease, a hereditary copper metabolism disorder, in humans; it acts both by competing with copper absorption in the bowel and by increasing excretion. It has also been found to have an inhibitory effect on angiogenesis, potentially via the inhibition of Cu ion dependent membrane translocation process involving a non-classical secretion pathway. This makes it an interesting investigatory treatment for cancer, age-related macular degeneration, and other diseases featuring excessive blood vessel deposition.
- Prasad, T. P.; Diemann, E. ; Müller, A. (1973). "Thermal decomposition of (NH4)2MoO2S2, (NH4)2MoS4, (NH4)2WO2S2 and (NH4)2WS4". Journal of Inorganic and Nuclear Chemistry 35 (6): 1895. doi:10.1016/0022-1902(73)80124-1.
- Müller, A.; Diemann, E.; Jostes, R.; Bögge, H. (1981). "Transition Metal Thio Anions: Properties and Significance for Complex Chemistry and Bioinorganic Chemistry". Angewandte Chemie International Edition in English 20 (11): 934. doi:10.1002/anie.198109341.
- Coucouvanis, D. (1998). Syntheses, Structures, and Reactions of Binary and Tertiary Thiomolybdate Complexes Containing the (O)Mo(Sx) AND (S)Mo(Sx) Functional Groups (x = 1, 2, 4). "Syntheses, Structures, and Reactions of Binary and Tertiary Thiomolydate Complexes Containing the (O)Mo(Sx) and (S)Mo(Sx) Functional Groups (x = 1, 2, 4)". Advances in Inorganic Chemistry. Advances in Inorganic Chemistry 45: 1–73. doi:10.1016/S0898-8838(08)60024-0. ISBN 978-0-12-023645-9.
- Brito, J. L. ; Ilija, M. ; Hernández, P. (1995). "Thermal and reductive decomposition of ammonium thiomolybdates". Thermochimica Acta 256 (2): 325. doi:10.1016/0040-6031(94)02178-Q.
- Lee, S. C.; Li, J.; Mitchell, J. C.; Holm, R. H., (1992). "Group 5 Tetrathiometalates: Simplified Syntheses and Structures". Inorg. Chem. 31 (21): 4333–4338. doi:10.1021/ic00047a021.
- Srinivasan, B. R.; Poisot, M.; Näther, C.; Bensch, W. (2004). "Diammonium tetrathiotungstate(VI), [NH4]2[WS4], at 150 K". Acta Crystallographica E E60 (11): i136–i138. doi:10.1107/S1600536804023761.
- Goodman, J. T.; Rauchfuss, T. B., (2002). "Tetraethylammonium-tetrathioperrhenate [Et4N][ReS4]". Inorganic Syntheses 33: 107–110.
- Nickel, W. (2003). "The Mystery of nonclassical protein secretion, a current view on cargo proteins and potential export routes". Eur. J. Biochem. 270 (10): 2109–2119. doi:10.1046/j.1432-1033.2003.03577.x. PMID 12752430.
- Brewer, G. J.; Hedera, P.; Kluin, K. J. et al. (2003). "Treatment of Wilson disease with ammonium tetrathiomolybdate: III. Initial therapy in a total of 55 neurologically affected patients and follow-up with zinc therapy". Arch Neurol 60 (3): 379–85. doi:10.1001/archneur.60.3.379. PMID 12633149.