What is "perrhenate"

n. (context inorganic chemistry English) The ReO₄^- oxyanion; any salt containing this anion

The perrhenate ion is the anion with the formula , or a compound containing this ion. The perrhenate anion is tetrahedral, being similar in size and shape to perchlorate and the valence isoelectronic permanganate. 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, features rhenium in the oxidation state of +7 with a d configuration. Solid perrhenate salts takes on the color of the cation.

Typical perrhenate salts are the alkali metal derivatives and ammonium perrhenate. These salts are prepared by oxidation of rhenium compounds with nitric acid followed by neutralization of the resulting perrhenic acid.