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Ammonium perrhenate

Names
Other names Ammonium perrhenate, Ammonium perrhenate(VII)
Identifiers
CAS Number	13598-65-7
3D model (JSmol)	Interactive image
ChemSpider	2341271
ECHA InfoCard	100.033.690
EC Number	237-075-6
PubChem CID	3084163
CompTox Dashboard (EPA)	DTXSID10893940
InChI InChI=1S/H3N.4O.Re/h1H3;;;;;/q;;;;-1;/p+1Key: HOJYZCWLNWENHS-UHFFFAOYSA-O InChI=1/H3N.4O.Re/h1H3;;;;;/q;;;;-1;/p+1/rH3N.O4Re/c;1-5(2,3)4/h1H3;/q;-1/p+1Key: HOJYZCWLNWENHS-WUACXKGRAA
SMILES (=O)(=O)=O.
Properties
Chemical formula	NH4ReO4
Molar mass	268.2359 g/mol
Density	3.97 g/cm, solid
Melting point	200°C (decomposes)
Solubility in water	2.8 g/100 mL (0 °C), 6.2 g/100 mL (20 °C), 12.0 g/100 mL (40 °C), 20.7 g/100 mL (60 °C), 32.3 g/100 mL (80 °C), 39.1 g/100 mL (90 °C)
Structure
Crystal structure	scheelite
Coordination geometry	N/A
Hazards
Flash point	Non-flammable
Related compounds
Other anions	Ammonium permanganate; ammonium pertechnetate
Other cations	Sodium perrhenate; perrhenic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). Y verify (what is  ?) Infobox references

Ammonium perrhenate (APR) is the ammonium salt of perrhenic acid, NH₄ReO₄. It is the most common form in which rhenium is traded. It is a white salt; soluble in ethanol and water, and mildly soluble in NH₄Cl. It was first described soon after the discovery of rhenium.

Structure

The crystal structure of APR resembles that of scheelite, with atomic cation is replaced by ammonium. The pertechnetate (NH₄TcO₄), periodate (NH₄IO₄), tetrachlorothallate (NH₄TlCl₄), and tetrachloroindate (NH₄InCl₄) follow this motif. 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. APR does not give hydrates.

Preparation

Ammonium perrhenate may be prepared from virtually all common sources of rhenium. The metal, oxides, and sulfides can be oxidized with nitric acid and the resulting solution treated with aqueous ammonia. Alternatively an aqueous solution of Re₂O₇ can be treated with ammonia followed by crystallisation.

Reactions

Ammonium perrhenate is weak oxidizer. It slowly reacts with hydrochloric acid:

NH₄ReO₄ + 6 HCl → NH₄ + Cl₂ ↑ + 3H₂O.

It is reduced to metallic Re upon heating under hydrogen:

2 NH₄ReO₄ + 7 H₂ → 2 Re + 8 H₂O + 2 NH₃

Ammonium perrhenate decomposes to volatile Re₂O₇ starting at 250 °C. When heated in a sealed tube at 500 °C, It decomposes to rhenium dioxide:

2NH₄ReO₄ → 2ReO₂ + N₂ + 4 H₂O

The ammonium ion can be displaced with some concentrated nitrates e.g. potassium nitrate,, silver nitrate, etc.:

NH₄ReO₄ + KNO₃ → KReO₄ ↓ + NH₄NO₃

It can be reduced to nonahydridorhenate with sodium in ethanol:

NH₄ReO₄ + 18Na + 13C₂H₅OH → Na₂ + 13NaC₂H₅O + 3NaOH + NH₃•H₂O.

References

1. ^ Georg Brauer (1954), Ammoniumperrhenat, Ferdinand Enke Verlag, p. 1108
2. ^ Lidin, R. (2007). Неорганическая химия в реакциях [Inorganic chemistry in reactions] (in Russian) (2nd ed.). Moscow: Drofa. p. 332. ISBN 978-5-358-01303-2.
3. Noddack, J.; Noddack, W. (1929). "Die Sauerstoffverbindungen des Rheniums" [The oxygen compounds of rhenium]. Zeitschrift für anorganische und allgemeine Chemie (in German). 181 (6): 1–37. Bibcode:1929NW.....17...93N. doi:10.1002/zaac.19291810102.
4. 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 (1): 76–81. Bibcode:1997AcCrB..53...76S. doi:10.1107/S0108768196011160.
5. R. J. C. Brown and S. L. Segel (1977). "Re, N, and H nuclear quadrupole couplings in NH₄ReO₄: Evidence for a possible phase transition". Journal of Chemical Physics. 67 (7): 3163–7. Bibcode:1977JChPh..67.3163B. doi:10.1063/1.435229.
6. O. Glemser "Ammonium Perrhenate" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, New York. vol. 1. p. 1476–85.
7. Richard J. Thompson (1966). "Ammonium Perrhenate". Inorganic Syntheses. Inorganic Syntheses. Vol. 8. pp. 171–173. doi:10.1002/9780470132395.ch44. ISBN 9780470132395.

• 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.

• Perrhenates
• Inorganic compounds
• Ammonium compounds