It reacts with antimony trioxide in a vacuum at 150 °C to give the iodide oxides PaOI3 and PaO2I; it reacts with protactinium(V) bromide at 350 °C to obtain mixed halides PaBr3I2.[2] It reacts with the monocarbide at 600 °C to give tetraiodide.[3]
Aristid von Grosse was able to produce pure metallic protactinium with the decomposition of protactinium(V) iodide.[4][5]
When heated at 300 °C for a long time, it decomposes and iodine is released:[1]
^Brown, David; De Paoli, Giovanni; Whittaker, Brian. Conversion of protactinium monocarbide to the penta- and tetrahalides. Journal of the Chemical Society, Dalton Transactions: Inorganic Chemistry (1972-1999), 1976. 14: 1336-1338.