Chemistry of the uranyl group—VI: Complexes of uranyl with hexamethylphosphoramide and urea

Abstract

Some uranyl complexes with hexamethylphosphoramide (HMPA) and urea were prepared and characterized. The compounds with the former ligand have the general formula UO 2 X 2·HMPA (where X = (C 2H 5) 2NCSe 2 −, (C 2H 5) 2NCS 2 − or CH 3COO −. For the acetato derivative a dimeric acetato-bridged structure is suggested. Some properties of UO 2(NO 3) 2·2(HMPA) are also described. With the latter ligand, in addition to the complexes UO 2(NO 3) 2·2urea and [UO 2(urea) 4(H 2O)](NO 3) 2 already known, the novel complexes UO 2(pycrate) 2·4urea and [UO 2(CH 3COO) 2·urea] 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 stoicheiometry were isolated.