Protactinium(V) bromides

Abstract

The preparation of protactinium pentabromide, PaBr₅, from the pentoxide has been investigated; the most satisfactory method is the reaction between bromine vapour and a mixture of protactinium pentoxide and carbon at 600–700°, in a sealed evacuated vessel. The yellow-green oxytribromide, PaOBr₃, which is obtained as a by-product of this reaction, is more conveniently prepared by the action of oxygen on the pentabromide at 350°. The oxytribromide disproportionates at 500° in a vacuum, to give the pentabromide and the white dioxybromide PaO₂Br. Some chemical properties, infrared spectra, and X-ray powder diffraction data are reported for these bromides.