Protactinium(V) chloride
Protactinium chloride is the chemical compound composed of protactinium and chlorine with the formula PaCl5. It forms yellow monoclinic crystals and has a unique structure composed of chains of 7 coordinate pentagonal bipyramids which share their edges.
Protactinium chloride can react with boron tribromide at high temperatures to form protactinium(V) bromide. It also reacts with fluorine to form protactinium(V) fluoride at high temperatures.