Rhenium(III) bromide explained

Rhenium(III) bromide is a chemical compound with the formula Re₃Br₉. It is a black lustrous crystalline solid. This compound reacts with water to form rhenium(IV) oxide and is isostructural with rhenium(III) chloride.^[1]

Preparation

This compound is prepared by the reaction of rhenium metal and bromine gas at 500 °C under nitrogen:

6Re + 9Br₂ → 2Re₃Br₉If there is oxygen in the atmosphere, it will instead form rhenium(III) oxybromide.

However, the most common method of producing this compound is by first reacting potassium hexabromorhenate(IV) with silver nitrate, which forms silver hexabromorhenite(IV), then this compound is heated to 600 °C to form rhenium(III) bromide.

K₂ReBr₆ + 2AgNO₃ → Ag₂ReBr₆ + 2KNO₃

6Ag₂ReBr₆ → 12AgBr + 3Br₂ + 2Re₃Br₉

An alternative method is a thermal decomposition of rhenium(V) bromide.

Notes and References

1. V. V. Ugarov . Electron-diffraction investigation of the structure of the Re₃Br₉ molecule . Journal of Structural Chemistry . 1971 . 12 . 2 . 286–288 . 10.1007/BF00739116 . 100857081 . English.