The perrhenate ion is the

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by convent ...

with the formula , or a compound containing this ion. The perrhenate anion is tetrahedral, being similar in size and shape to

perchlorate A perchlorate is a chemical compound containing the perchlorate ion, . The majority of perchlorates are commercially produced salts. They are mainly used as oxidizers for pyrotechnic devices and to control static electricity in food packaging. Per ...

and the valence

isoelectronic Isoelectronicity is a phenomenon observed when two or more molecules have the same structure (positions and connectivities among atoms) and the same electronic configurations, but differ by what specific elements are at certain locations in the ...

permanganate A permanganate () is a chemical compound containing the manganate(VII) ion, , the conjugate base of permanganic acid. Because the manganese atom is in the +7 oxidation state, the permanganate(VII) ion is a strong oxidizing agent. The ion is a tra ...

. The perrhenate anion is stable over a broad pH range and can be precipitated from solutions with the use of organic cations. At normal pH, perrhenate exists as metaperrhenate (), but at high pH mesoperrhenate () forms. Perrhenate, like its conjugate acid

perrhenic acid Perrhenic acid is the chemical compound with the formula . It is obtained by evaporating aqueous solutions of . Conventionally, perrhenic acid is considered to have the formula , and a species of this formula forms when rhenium(VII) oxide sublime ...

, features rhenium in the

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

of +7 with a d⁰ configuration. Solid perrhenate salts takes on the color of the cation.

Preparation

Typical perrhenate salts are the alkali metal derivatives and

ammonium perrhenate 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 ...

. These salts are prepared by oxidation of rhenium compounds with nitric acid followed by neutralization of the resulting perrhenic acid.O. Glemser "Rhenium" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1476-85. Addition of

tetrabutylammonium chloride Tetrabutylammonium chloride is the organic compound with the formula (C4H9)4NCl. A white water-soluble solid, it is a quaternary ammonium salt of chloride. It is a precursor to other tetrabutylammonium salts. Often tetrabutylammonium bromide ...

to aqueous solutions of sodium perrhenate gives tetrabutylammonium perrhenate, which is soluble in organic solvents.

Reactions of perrhenates

Basicity

Perrhenate anion is a weaker base than or but stronger than or . Silver perrhenate reacts with

trimethylsilyl chloride Trimethylsilyl chloride, also known as chlorotrimethylsilane is an organosilicon compound ( silyl halide), with the formula (CH3)3SiCl, often abbreviated Me3SiCl or TMSCl. It is a colourless volatile liquid that is stable in the absence of water. ...

to give the silyl "ester" (CH₃)₃SiOReO₃.

Reaction with sulfide

With sulfide sources such as

hydrogen sulfide Hydrogen sulfide is a chemical compound with the formula . It is a colorless chalcogen-hydride gas, and is poisonous, corrosive, and flammable, with trace amounts in ambient atmosphere having a characteristic foul odor of rotten eggs. The unde ...

, converts to tetrathioperrhenate anion . An intermediate is eO₃Ssup>−.

Dehydration

Heating ammonium perrhenate gives Re₂O₇.

Redox

Unlike the related permanganate, perrhenate is nonoxidising. Replacement of some

oxo ligand A transition metal oxo complex is a coordination complex containing an oxo ligand. Formally O2-, an oxo ligand can be bound to one or more metal centers, i.e. it can exist as a terminal or (most commonly) as bridging ligands (Fig. 1). Oxo ligan ...

s induces redox however. Thus the perrhenate ion reacts with the

cyanide Cyanide is a naturally occurring, rapidly acting, toxic chemical that can exist in many different forms. In chemistry, a cyanide () is a chemical compound that contains a functional group. This group, known as the cyano group, consists of ...

to give ''trans''- eO₂(CN)₄sup>3−. Treatment of tetrabutylammonium perrhenate with

produces the

oxychloride In chemistry, molecular oxohalides (oxyhalides) are a group of chemical compounds in which both oxygen and halogen atoms are attached to another chemical element A in a single molecule. They have the general formula , where X = fluorine (F), chlor ...

of Re(V): :Bu₄N eO₄ + 6 Me₃SiCl → Bu₄N eOCl₄ + 3 (Me₃Si)₂O + Cl₂

Complement to pertechnetate

The chemistry of the perrhenate ion is similar to that of the

pertechnetate The pertechnetate ion () is an oxyanion with the chemical formula . It is often used as a convenient water-soluble source of isotopes of the radioactive element technetium (Tc). In particular it is used to carry the 99mTc isotope (half-life 6 hou ...

ion . For this reason, perrhenate is sometimes used as a carrier for trace levels of pertechnetate, for instance in nuclear medicine scanning procedures. Perrhenate is also used as a safer alternative to pertechnetate for nuclear waste vitrification studies, such as volatility or encapsulation in solids.{{cite journal , last1=Luksic , first1=Steven , last2=Riley , first2=Brian , last3=Parker , first3=Kent , last4=Hrma , first4=Pavel , title=Sodalite as a vehicle to increase Re retention in waste glass simulant during vitrification , journal=Journal of Nuclear Materials , volume=479 , year=2016 , pages=331–337 , doi=10.1016/j.jnucmat.2016.07.002 , bibcode=2016JNuM..479..331L , doi-access=free