Uranium acetonitrile salt

A pure acetonitrile complex of uranium(IV) iodide cannot be isolated,8 but the salt [(CeHj As UI (red) can be readily prepared by the procedure described above in subsection 1, the pure halide being used instead of the acetonitrile complex. f( C H )4NJPaBr6 is extremely soluble in acetonitrile but it can be isolated in 100% yield by room-temperature evaporation of the solvent containing equimolar amounts of the component bromides. 

Diorgano ditellurium compounds react with transition metal salts and carbonyl complexes to form coordination compounds (Table 5, p. 283). Complexes with the following transition metals have been reported Ti, Cr, Mo, W, Mn, Re, Fe, Ir, Ni, Pd, Pt, Cu, Ag, Cd, Hg, Yb, and U. In many of these complexes, the organyltelluro group bridges the metal atoms in binuclear complexes. The Te —Te bond seems to remain intact upon complexation to mercury halides, rhenium carbonyls, and uranium pentachloride. For details on tellurolatO bridged complexes see p. 212. Complexes with SnCl are also known. Diphenyl ditellurium and bis[4-ethoxyphenyl] ditellurium formed charge-transfer complexes when equimolar amounts of the ditellurium compound and tetracyano-p-quinodime-thane were refluxed in acetonitrile. ... 

Nitriles. Acetonitrile adducts have been reported for several uranyl salts, including the chloride and nitrate. Although lower metal coordination numbers (e.g., five) have been suggested in the formulation of some of these compounds, it is likely that the species contain six- or seven-coordinate metal ions. As illustration of this, the molecular structure of U02Cl2(MeCN)2(H20) " possesses a seven-coordinate uranium center, with mutually traro-acetonitrile and chloride ligands. 

Sodium Hexafluorouranate(V) Uranium pentafluoride (2.00 g) and dried NaF (0.25 g) are combined in a 250-mL flask in a drybox. The flask is then attached to a vacuum line, and approximately 150 mL of dry acetonitrile is vacuum transferred into the flask. (The acetonitrile can be dried by distillation from P4O10 or CaH2.) The mixture is allowed to warm to room temperature. With stirring, the NaF gradually dissolves over a period of 12 hours. The solvent is removed in vacuo, quantitatively yielding NaUF6 in the rhombohedral form (X-ray powder diffraction). The potassium salt is prepared similarly. 

The hexafluorouranate products are all air-sensitive, pale blue-green powders. The reaction of [UFg] with water produces [UFs] and [U02F4] whose presence in the product may be determined by the visible-near-infrared spectrum in acetonitrile. The characteristic fundamental V3 mode of [UFe] is found at 525 cm" in the infrared spectrum of the salts. Reactions of tetra-alkylammonium fluorides with uranium pentafluoride in acetonitrile yield the corresponding [UF ]" salts, but these salts were found to be unstable under vacuum after removal of acetonitrile. They can be prepared less conveniently in HF, however. The uranium in NaUFe is six oordinate in solution and in the solid state, whereas in KUFj the uranium is six-coordinate in solution and eight-coordinate in the solid state. The exact geometry of the isolated... 

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