Preparation and some chemical properties of protactinium metal

Abstract

The preparation of protactinium metal by a modified van Arkel technique is described. The product exhibits the body-centred tetragonal structure with a₀= 3.931(1) and c₀= 3.236(1)Å. Conditions for conversion of the metal into the tetra- and penta-halides (PaX₄, X = Cl or Br; PaX₅, X = F, Cl, Br, or I) by reactions involving a variety of halogenating agents are described. Reaction with gaseous hydrogen yields either α-PaH₃(250 °C) or β-PaH₃(400 °C) whrch are isostructural with their uranium analogues. The stability of the metal on exposure to the atmosphere has been confirmed.