▁by ▁b rom ine , ▁a ▁vol atile ▁metal ▁b rom ide , ▁carbon ▁t et rab rom ide , ▁or ▁an ▁organ ic ▁b rom ide . ▁For ▁example , ▁n io b ium ( V ) ▁ox ide ▁react s ▁with ▁carbon ▁t et rab rom ide ▁at ▁ 3 7 0   ° C ▁to ▁form ▁n io b ium ( V ) ▁b rom ide . ▁Another ▁method ▁is ▁hal ogen ▁exchange ▁in ▁the ▁presence ▁of ▁excess ▁" hal ogen ating ▁re agent ", ▁for ▁example : ▁Fe Cl 3 ▁+ ▁B Br 3 ▁( ex cess ) ▁→ ▁Fe Br 3 ▁+ ▁B Cl 3 ▁When ▁a ▁lower ▁b rom ide ▁is ▁wanted , ▁either ▁a ▁higher ▁hal ide ▁may ▁be ▁reduced ▁using ▁hydro gen ▁or ▁a ▁metal ▁as ▁a ▁reducing ▁agent , ▁or ▁thermal ▁decomposition ▁or ▁dis pro port ion ation ▁may ▁be ▁used , ▁as ▁follows : ▁▁ 3 ▁W Br 5 ▁+ ▁Al ▁▁ 3 ▁W Br 4 ▁+ ▁Al Br 3 ▁ ▁Eu Br 3 ▁+ ▁ ▁H 2 ▁→ ▁Eu Br 2 ▁+ ▁H Br ▁▁ 2 ▁Ta Br 4 ▁ ▁Ta Br 3 ▁+ ▁Ta Br 5 ▁ ▁Most ▁of ▁the ▁b rom ides ▁of ▁the ▁pre - transition ▁met als ▁( groups ▁ 1 , ▁ 2 , ▁and ▁ 3 , ▁along ▁with ▁the ▁l anth an ides ▁and ▁act in ides ▁in ▁the ▁+ 2 ▁and ▁+ 3 ▁ox id ation ▁states ) ▁are ▁mostly ▁ion ic , ▁while