Protactinium halides mixed

Protactinium tetrafluoride, like the other actinide tetrafluorides, possesses the 8-coordinate UF4-type of structure (Table III) but no bond distances are available. It is easily the most stable tetravalent halide of protactinium and can be handled in the atmosphere, at least for a limited period, without hydrolysis or oxidation occurring. As mentioned earlier it is the usual starting material for the preparation of protactinium metal. Tetrafluoride hydrates have not been fully characterized, but a mixed fluorosulfate, PaF2S04 2H20 can be precipitated from aqueous solution (131). Protactinium tetrafluoride is soluble in aqueous ammonium fluoride solutions, for which some spectral properties have been recorded (4, 83). 

The only mixed halide known is PaBrglg, a black, crystalline solid which is isostructural with the pentaiodide. It is formed (40) when equimolar amounts of the pentabromide and pentaiodide are heated together at 300°C. Numerous uranium(IV) mixed halides are known (34) and undoubtedly many protactinium(IV) and (V) mixed halides could be prepared, but this field has so far been neglected. 

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See also in sourсe #XX -- [ ]

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