Ammonium perrhenate

Chembox new
ImageFile = Ammonium perrhenate.svg
ImageFile1 = Ammonium_perrhenate.jpg
ImageName = Ammonium perrhenate
OtherNames = Ammonium perrhenate,
Ammonium perrhenate(VII)
Section1 = Chembox Identifiers
CASNo = 13598-65-7
Section2 = Chembox Properties
Formula = NH₄ReO₄
MolarMass = 268.2359 g/mol
Density = 3.97 g/cm³, solid
Solubility = soluble.
MeltingPt = °C
BoilingPt =
Section3 = Chembox Structure
Coordination = N/A
CrystalStruct = scheelite
Section7 = Chembox Hazards
ExternalMSDS =
EUClass = Not listed.
FlashPt = Non-flammable.
Section8 = Chembox Related
OtherAnions = Ammonium manganate; ammonium pertechnetate
OtherCations = Sodium perrhenate; perrhenic acid
OtherCpds =

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%.

tructure

The crystal structure of APR is that of scheelite, in which the atomic cation is replaced by the ammonium molecular cationcite journal | journal = Acta Crystallographica | author = I.P. Swainson and R.J.C. Brown | title = Refinement of ammonium perrhenate structure using a pseudo-spin model for the ammonium ion orientation |volume = B53| pages = 76-81 | year = 1997|doi = 10.1107/S0108768196011160] . 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 coefficientcite journal | journal = Journal of Chemical Physics | author = R.J.C. Brown and S.L. Segel | title = ¹⁸⁷Re, ¹⁴N, and ²H nuclear quadrupole couplings in NH₄ReO₄: Evidence for a possible phase transition |volume = 67| pages = 3163-7 | year = 1977|doi = 10.1063/1.435229] .

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).

Preparation

Ammonium perrhenate may be prepared from elemental rhenium by dissolving in ammoniacal hydrogen peroxide (also known as base piranha).

Reactions

Pure rhenium powder can be produced from APR by reducing it with hydrogen:cite book | title = Handbook of Inorganic Chemicals | author = Pradyot Patnaik | publisher = McGraw-Hill | location = New York | isbn = 0070494398 | pages = 789-790]

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

References

* cite journal
title = The Salts of Perrhenic Acid. I. The Alkali Metals and Ammonium
author = Wm. T. Smith, S. Harmon Long
journal = Journal of the American Chemical Society
volume = 70
issue = 1
year = 1948
pages = 354–356
doi = 10.1021/ja01181a110

Further reading

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