Ammonium perrhenate
| Ammonium perrhenate | |
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Other names
Ammonium perrhenate, |
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| Identifiers | |
| CAS number | 13598-65-7 |
| ChemSpider | 2341271  |
| Jmol-3D images | Image 1 |
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| Properties | |
| Molecular formula | NH4ReO4 |
| Molar mass | 268.2359 g/mol |
| Density | 3.97 g/cm³, solid |
| Melting point |
°C |
| Solubility in water | soluble. |
| Structure | |
| Crystal structure | scheelite |
| Coordination geometry |
N/A |
| Hazards | |
| EU classification | Not listed. |
| Flash point | Non-flammable. |
| Related compounds | |
| Other anions | Ammonium manganate; ammonium pertechnetate |
| Other cations | Sodium perrhenate; perrhenic acid |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Ammonium perrhenate (APR) is the ammonium salt of perrhenic acid, NH4ReO4. This is the most common form in which rhenium is traded. Prices are quoted in US Dollars per kg Rhenium content. Rhenium content of APR is typically 69.0 - 69.4%.
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[edit] Structure
The crystal structure of APR is that of scheelite, in which the atomic cation is replaced by the ammonium molecular cation[1]. It undergoes a molecular orientational ordering transition on cooling without change of space group, but with a highly anisotropic change in the shape of the unit cell, resulting in the unusual property of having a positive temperature and pressure Re NQR coefficient[2].
NH4ReO4 can be regarded as the prototype structure of a family of ammonium scheelites, which include the pertechnetate (NH4TcO4), periodate (NH4IO4), tetrachlorothallate (NH4TlCl4) and tetrachloroindate (NH4InCl4)[1].
[edit] Preparation
Ammonium perrhenate may be prepared from elemental rhenium by dissolving in ammoniacal hydrogen peroxide (also known as base piranha).[3]
[edit] Reactions
Pure rhenium powder can be produced from APR by reducing it with hydrogen:[3]
- 2 NH4ReO4 + 7 H2 → 2 Re + 8 H2O + 2 NH3
[edit] References
- ^ a b I.P. Swainson and R.J.C. Brown (1997). "Refinement of ammonium perrhenate structure using a pseudo-spin model for the ammonium ion orientation". Acta Crystallographica B53: 76–81. doi:10.1107/S0108768196011160.
- ^ R.J.C. Brown and S.L. Segel (1977). "187Re, 14N, and 2H nuclear quadrupole couplings in NH4ReO4: Evidence for a possible phase transition". Journal of Chemical Physics 67 (7): 3163–7. doi:10.1063/1.435229.
- ^ a b Pradyot Patnaik (2003). Handbook of Inorganic Chemicals. New York: McGraw-Hill. pp. 789–790. ISBN 0-07-049439-8.
- Wm. T. Smith, S. Harmon Long (1948). "The Salts of Perrhenic Acid. I. The Alkali Metals and Ammonium". Journal of the American Chemical Society 70 (1): 354–356. doi:10.1021/ja01181a110.
[edit] Further reading
- Richard J. Thompson, Tung-Ch'Ing Wang, Jacob Kleinberg, George M. Adams, Burl E. Bryant (1966). "Ammonium Perrhenate". Inorganic Syntheses 8: 171–173. doi:10.1002/9780470132395.ch44.
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