The oxidation of uranium(IV) by n-phenylbenzohydroxamic acid and the structure of the reaction product: chlorodioxo-n-phenylbenzohydroxamato-bis(tetrahydrofuran)uranium(VI)

Uranium tetrachloride has been quantitatively oxidized via an oxygen transfer reaction wih two equivalents of N-phenylbenzohydroxamic acid anion (PBHA) in tetrahydrofuran (THF) to form benzanilide and UO2Cl(PBHA)(THF)2. The structure of the uranyl complex has been determined by X-ray diffraction data collected by counter methods. The linear uranyl ion has an average U-O distance of 1.75(3) A, and is surrounded by a planar pentagonal array composed of two hydroxamate oxygen atoms, a chloride ion and two THF oxygens, such that the chloride ion is opposite the hydroxamate group. That the THF and phenyl rings are twisted from this equatorial plane limits the molecular geometry to that of the Cl point group. The U-Cl length is 2.68(1) A and the other U-O bonds average 2.40 A. Refinement fitting 88 parameters to 1248 reflections led to an R-factor of 6.9%. Unit cell dimensions in the space group C2 are given and the calculated density is 1.85 g-cm-3 for Z = 4. (author)