Carbonyl dibromide: a novel reagent for the synthesis of metal bromides and bromide oxides

Carbonyl dibromide reacted with a wide selection of d- and f-block transition-metal oxides to form either the metal bromide or bromide oxide; the reactions are driven by the elimination of carbon dioxide. In a typical reaction the metal oxide was treated with an eight-fold excess of COBr 2 in a sealed Carius tube at 125 °C for 10 d (to ensure complete reaction of the metal oxide). As COBr 2 and the reaction by-products (CO 2 , CO and Br 2 ) are all volatile, the desired products were obtained in essentially quantitative yield and a high degree of purity. Under these conditions V 2 O 5 , MoO 2 , Re 2 O 7 , Sm 2 O 3 and UO 3 were converted into VOBr 2 , MoO 2 Br 2 , ReOBr 4 , SmBr 3 and UOBr 3 , respectively. This route offers great potential for the preparation of many known bromide derivatives of the transition metals, lanthanides and actinides, in a very convenient manner, and also for the synthesis of new materials. A modified synthesis of carbonyl dibromide was elaborated, and its 17 O NMR and electron impact mass spectra are reported for the first time.