Polonium complexes thiourea

An interesting method (88) for the separation of trace amounts of polonium makes use of the volatility of some, as yet unidentified, organic compounds. Polonium complexes with diphenylearbazonc, diphenylear-bazide and diphenylthiocarbazone sublime below 100°C under atmospheric pressure and those with thiourea, 8-hydroxyquinoline, s-diphenylthiourea, thioseinicarbazide and other related compounds sublime below 160°C under the same conditions. Thus trace polonium has been separated from dilute nitric acid in the presence of diphenyl carbazide by steam distillation. 

Trace polonium is extracted from aqueous acetate solution by 8-hy-droxyquinoline in chloroform, probably forming a 1 1 compound this sublimes at 140°C (81). The thionalide complex appears to have 2 molecules of ligand to each polonium atom volatile complexes with thiourea, thio-semicarbazide, diphenylcarbazide, and analogous reagents have also been reported (81). 

The group VIB cyanides, thiocyanates and selenocyanates and their complexes with species such as thiourea have been described.1,45 For example, the tellurium dithiocyanate complex has been prepared45 by treatment of tellurium dichloride or tellurium dibromide with ammonium thiocyanate. It seems that little information exists on the preparation of tellurocyanates and there is a sparsity of data on polonium derivatives. Indeed, the only known cyanide of polonium is probably a salt of the quadrivalent element.1... 

Complexes of polonium with sulfur donor atoms appear to be less common, although there is some evidence that polonium is complexed by thiourea and of the formation of a volatile polonium diethylditMocarbamate. 

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