Chemistry of the uranyl group

Some uranyl complexes with hexamethylphosphoramide (HMPA) and urea were prepared and characterized. The compounds with the former ligand have the general formula UO2X2.HMPA (where X = (C2H5)2NCSe2-, (C2H5)2NCS2- or CH3COO-). For the acetato derivatives a dimeric acetato-bridged structure is suggested. Some properties of UO2(NO3)2.2(HMPA) are also described. With the latter ligand, in addition to the complexes UO2(NO3)2.2urea and [UO2(urea)4(H20)](NO3)2 already known, the novel complexes UO2(pycrate)2.4urea and [UO2(CH3COO)2.urea]sub(n) (where n is probably 2) have been prepared. All attempts to obtain urea complexes of uranyl diethyldithio- or diethyldiselenocarbamate failed and only adducts of unsatisfactory stoichiometry were isolated. (author)