Rhenium(III) bromide

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][4]

Rhenium(III) bromide

Names
Other names Trirhenium nonabromide Rhenium tribromide
Identifiers
CAS Number	13569-49-8 Y
3D model (JSmol)	Interactive image
ChemSpider	15750935
ECHA InfoCard	100.033.607
EC Number	236-984-5
PubChem CID	83579
CompTox Dashboard (EPA)	DTXSID8065535
InChI InChI=1S/3BrH.Re/h3*1H;/q;;;+3/p-3
SMILES Br[Re](Br)Br
Properties
Chemical formula	Re3Br9
Molar mass	425.92 g/mol
Appearance	Black lustrous solid[1]
Melting point	500 °C (932 °F; 773 K)[2] (sublimes)
Solubility in water	Reacts[1]
Solubility	Sparingly soluble in ether and acetone, reacts with methanol and ammonia[1]
Structure
Molecular shape	Trimeric
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	−164.4 kJ/mol[3]
Related compounds
Other anions	Rhenium(III) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

This compound is prepared by the reaction of rhenium metal and bromine gas at 500 °C under nitrogen:^[2]

6Re + 9Br₂ → 2Re₃Br₉

If there is oxygen in the atmosphere, it will instead form rhenium(III) oxybromide.^[2]

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.^[1][3]

K₂ReBr₆ + 2AgNO₃ → Ag₂ReBr₆ + 2KNO₃

6Ag₂ReBr₆ → 12AgBr + 3Br₂ + 2Re₃Br₉

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