Tungsten Pentabromide, WBr₅

Tungsten Pentabromide, WBr₅, is best prepared by passing a current of bromine vapour, which may be diluted with carbon dioxide but must be entirely free from air and moisture, over tungsten at a red heat; by heating the hexachloride at 300° C. in dry hydrogen bromide a less pure product results.

This compound forms lustrous dark brown hygroscopic crystals which melt at 276° C. and boil at 333° C., and which with excess of water yield the blue oxide and hydrobromic acid, though they are soluble in the common anhydrous organic solvents. They are reduced by hydrogen to the dibromide and to the pyrophoric metal; with oxygen, the oxybromides are formed.