Praseodymium (3) solvation in aqueous-dimethyl sulfoxide solutions

Praseodymium (3) ion solvation in aqueous-dimethyl sulfoxide solutions with the concentration of dimethyl sulfoxide (DMSO) from 0 to 100 mol% and with the constant concentration of PrCl3 equalling 0.0183 mol/l is studied by the electron spectroscopy method. It is shown that change in spectral characteristics of Pr3 ion, when the concentration of DMSO in the solution increases, is connected with the DMSO substitution for H2O in the 1st coordination sphere of a complexing ion. Practically complete DMSO substitution for H2O in the 1st Pr3 sphere occurs at approximately 50 mol% concentration of DMSO and transition from the (Pr(H2O)9)3+ (in aqueous solution) to the (Pr(DMSO)8)3+ (in aqueous-organic mixture with DMSO concentration > 50 mol%) takes place. Displacement of Pr3 absorption bands to the red side and increase of their intensity relate to the increase of Me-0 bond covalence, when substituting DMSO for H2O in the coordination environment of Pr3