Ammonium tetrathiomolybdate
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| Ammonium tetrathiomolybdate | |
|---|---|
| Image:Ammonium tetrathiomolybdate.jpg | |
| General | |
| Systematic name | Ammonium tetrathiomolybdate |
| Other names | ammonium thiomolybdate |
| Molecular formula | H8N2MoS4 |
| SMILES | ? |
| Molar mass | 260.28 g/mol |
| Appearance | red crystals |
| CAS number | [15060-55-6] |
| Properties | |
| Density and phase | ? g/cm3 |
| Solubility in water | |
| Other solvents | |
| Melting point | decomp 300 °C |
| Basicity (pKb) | decomposes |
| Structure | |
| Coordination geometry |
? |
| Crystal structure | |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | toxic |
| NFPA 704 | |
| R/S statement | R: ? S: ? |
| RTECS number | QA4668250 |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Related compounds | |
| Related compounds | (NH4)2WS4, MoS2 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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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).
Contents |
[edit] Preparation and structure
The compound is prepared by treating solutions of molybdate with hydrogen sulfide in the presence of ammonia:[1]
- (NH4)2MoO4 + 4 H2S → (NH4)2MoS4 + 4 H2O
(NH4)2MoS4 is a salt consisting of the the tetrahedral [MoS4]2- anion.
[edit] Reactions
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 the organic "quat" salts such as (NEt4)2MoS4 and (PPh4)2MoS4 (Et = C2H5, Ph = C6H5).[2] These organic salts are soluble in polar organic solvents such as acetonitrile and dmf.
The thermal decomposition of (NH4)2MoS4 leads to MoSx (2 < x < 3), which are of interest as catalysts for hydrodesulfurization.[3]
[edit] Related compounds
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]
[edit] References
- ^ Müller, A.; Diemann, E.; Jostes, R.; Bögge, H., "Transition Metal Thio Anions: Properties and Significance for Complex Chemistry and Bioinorganic Chemistry", Angewandte Chemie International Edition in English, 1981, volume 20, 934.
- ^ Coucouvanis, D., "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, 1998, volume 45, 1-73
- ^ Alonso, G.; Berhault, G.; Aguilar, A.; Collins, V.; Ornelas, C.; Fuentes, S.; Chianelli, R. R., "Characterization and HDS Activity of Mesoporous MoS2 Catalysts Prepared by in Situ Activation of Tetraalkylammonium Thiomolybdates", J. Catal., 2002, 208, 359-369
- ^ a b c Lee, S. C.; Li, J.; Mitchell, J. C.; Holm, R. H., "Group 5 Tetrathiometalates: Simplified Syntheses and Structures", Inorganic Chemistry, 1992, 31, 4333-4338.
- ^ Srinivasan, B. R.; Poisot, M.; Näther, C.; Bensch, W., "Diammonium tetrathiotungstate(VI), (NH4)2[WS4], at 150 K", Acta Crystallographica, Section E: Structure Reports Online, 2004, E60, i136-i138.
- ^ Goodman, J. T.; Rauchfuss, T. B., "Tetraethylammonium-tetrathioperrhenate Et4N(ReS4)." Inorganic Syntheses, 2002, volume 33, pp. 107-110
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