Thermodynamic and Spectroscopic Investigations on the Interaction of Uranyl(VI) with Neutral N- and O-Donors in Dimethyl Sulfoxide.

The thermodynamic functions Delta G circle minus, Delta H circle minus and Delta S circle minus for the formation of uranyl(VI) complexes with the, tridentate compound 4-azaheptane-1,7-diamine and with tetradentate 3,6-diazaoctane-1,8-diamine and 4,7-diazadecane-1,10-diamine have been determined in anhydrous dimethyl sulfoxide (dmso) by means of potentiometric, spectroscopic, and calorimetric measurements at 25 degrees C in a 0.1 mol dm(-3) ionic medium. The data are discussed together with those for other polyamines previously investigated. Factors affecting the complexation of uranyl(VI) by these strongly basic ligands in anhydrous dmso are elucidated. Spectroscopic and calorimetric evidence has been obtained which demonstrates that polyglycols having molecular frameworks similar to those of some of the polyamines do not form complexes with uranyl(VI) in this solvent.