Ammonium tetrathiomolybdate
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Other names
ammonium thiomolybdate
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3D model (
JSmol ) |
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ECHA InfoCard
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100.167.865 |
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UNII | |
CompTox Dashboard (EPA)
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Properties | |
(NH4)2MoS4 | |
Molar mass | 260.28 g/mol |
Appearance | red crystals |
Melting point | decomp ~ 155 °C[1] |
Basicity (pKb) | decomposes |
Structure | |
[2] | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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toxic |
GHS labelling: | |
Warning | |
H315, H319, H335 | |
P261, P264, P271, P280, P302+P352, P304+P340, P305+P351+P338, P312, P321, P332+P313, P337+P313, P362, P403+P233, P405, P501 | |
Related compounds | |
Related compounds
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(NH4)2[WS4], MoS2 |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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 (see metallate) 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
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:[3]
- (NH4)2MoO4 + 4 H2S → (NH4)2MoS4 + 4 H2O
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 salts of quaternised organic cations, such as [NEt4]2[MoS4] and [PPh4]2[MoS4] (Et = C2H5, Ph = C6H5).[4] These organic salts are soluble in polar organic solvents such as acetonitrile and dmf.
The thermal decomposition of [NH4]2[MoS4] leads to molybdenum trisulfide (MoS3), ammonia (NH3) and hydrogen sulfide (H2S), beginning at 155 °C till 280 °C.[1]
- (NH4)2MoS4 → 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.[5]
- MoS3 + H2 → MoS2 + H2S
Related compounds
Several related thio and seleno anions are known including (A = alkali metal cation, [PPh4]+, [NEt4]+)
- A3[VS4]:[6] ammonium tetrathiovanadate[7]
- A3[NbS4][6]
- A3[TaS4][6]
- A2[MoSe4]
- A2[WS4]: diammonium tetrathiotungstate ,[8][9] piperidinium tetrathiotungstate[10]
- A2[WSe4]: ammonium tetraselenotungstate ,[7] tetraethylammonium tetraselenotungstate[11]
- A[ReS4][12]
- (C5H14NO)2MoS4 (bis-choline tetrathiomolybdate)[13]
More complex tetrahedral anions include A2[MoS4−xOx] and A2[WS4−xOx]
Uses
Ammonium tetrathiomolybdate was first used therapeutically in the treatment of
Various phase II clinical trial of ATTM for copper depletion in cancer have been performed.[17]
ATTM has also been found to have an inhibitory effect on
References
- ^ .
- PMID 21579587.
- .
- ISBN 978-0-12-023645-9.
- .
- ^ .
- ^ .
- .
- .
- .
- .
- ISBN 0471208256.
- ^ Compound Summary for Bis-choline tetrathiomolybdate
- ^ PMID 12633149.
- PMID 16606763.
- PMID 19595438.
- )
- PMID 12752430.