Niobium(V) bromide

Niobium(V) bromide is the inorganic compound with the formula Nb₂Br₁₀. Its name comes from the compound's empirical formula, NbBr₅. It is a diamagnetic, orange solid that hydrolyses readily. The compound adopts an edge-shared bioctahedral structure, which means that two NbBr₅ units are joined by a pair of bromide bridges. There is no bond between the Nb centres. Niobium(V) chloride, niobium(V) iodide, tantalum(V) chloride, tantalum(V) bromide, and tantalum(V) iodide all share this structural motif.

Synthesis

Niobium(V) bromide can be prepared by the reaction of bromine with niobium metal at 230-250 °C in a tube furnace. It can also be produced from the more accessible oxide by metathesis using aluminium tribromide:

Nb₂O₅ 3.3 AlBr₃ → 2 NbBr₅ 3.3 Al₂O₃

A challenge with the latter method is the occurrence of NbOBr₃ as an impurity.