Photochemical reactions of pentakis(N,N-dimethylformamide)-dioxouranium(VI) ions in nonaqueous solutions

Photochemical reactions of [UO2(dmf)5]2+ (dmf = N, N-dimethylformamide) ions were investigated in DMF and acetone solutions. The photolysis product of [UO2(dmf)5]2+ at the initial stage was U(V), which was so stable in acid-free organic solvents in the dark that the absorption spectrum of U(V) was easily obtained in DMF. The molar extinction coefficient of U(V) was determined to be 45.5 ± 1.5 M-1 cm-1 (M = mol dm-3) at 755 nm. The formation of U(V) seems to proceed through the intramolecular reaction (ki) and the lower limit of ki was determined to be about 107 s-1 from the lifetime of excited uranyl ions by using a laser flash photolysis. (author)