Protactinium oxychloride

Protactinium (of mass number 231) is found in nature iu all uranium ores, since it is a long-lived member of the uranium series. It occurs in such ores to the extent of about part per million parts of uranium. An efficient method for the separation of protactinium is by a carrier technique using zirconium phosphate which, when precipitated from strongly acid solutions, coprecipitates protactinium nearly quantitatively. Then the protactinium is separated from the carrier by fractional crystallization of zirconium oxychloride. 

No structural data are available for the pentavalent oxychlorides, but the positions of the protactinium-oxygen stretching vibrations... 

The oxytriiodide, PaOIs, and dioxymonoiodide, PaOgl, have both been prepared (40) by reacting the pentaiodide with the stoichiometric amount of antimony sesquioxide [Eqs. (9) and (10)]. PaOIs, a dark brown solid, is thermally unstable [Eq. (11)] in vacuo like certain of the oxychlorides and oxybromides. The positions of the protactinium-oxygen... 

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