N,N-Dimethylacetamide (DMA) Complexes of Uranium (IV) Mixed Halides
The uranium tetrachloride-DMA complex, 2 UCl4.5 DMA, and the corresponding neptunium (IV) and plutonium (IV) complexes have been known for some years (1) but, apart from the probable presence of one or more bridging DMA molecules in the compounds, no data on their constitution are available. Although they are essentially non-electrolytes in organic solvents such as DMA, methyl cyanide or nitromethane, the chloride ion can be completely replaced by nitrate using the silver salt (2), thiocyanate with the potassium salt (3) or Perchlorate, again with the silver salt (4), the resulting compounds having the compositions [U(NO3)4]2(DMA)5 , U(SCN)4(DMA)4 and U(C10) (DMA) . The first two of these are non-electrolytes and the third is, as would be expected, a 4:1 electrolyte in nitromethane (5). The chloride ion can also be replaced by iodide on treatment of the chloride complex with a large excess of sodium iodide in non-aqueous solvents, but this does not go to completion in organic solvents at room temperature, unlike the other replacement reactions. With DMA as solvent, the product of the reaction is the pale green complex UI2 Cl2(DMA)5 even at 100° (5). This compound is precipitated from solution in DMA by ethyl acetate, in which the excess of sodium iodide and any uranyl halide formed by atmospheric oxidation are both soluble.
KeywordsMolar Conductivity Chloride Complex Silver Salt DIMETHYLACET Amide Sodium Iodide
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