Spectrophotometric study of uranium(VI) complex equilibria with N,N-dimethylformamide

Spectrophotometric study of solvation equilibria of uranium(VI) with N,N-dimethyl formamide (DMF) in solutions with ionic strength I = 3.0 mol.dm(-3) (Na, H)ClO4 shows that DMF forms with UO22+ several relatively stable solvates absorbing in VIS range (350-490 nm). The absorbance of UO22+ bands increases and their absorption maxima shift to longer wavelengths while uranyl solvates are formed stepwise with increasing concentration of DMF. Areas of prevailing existence of individual solvates with stoichiometry 1 : n (n = 1, 2, 4, 6) have been found and their stability constants and molar absorption coefficients estimated using both graphical methods and computer minimization programs.