Fluorescence and IR studies on the hydration state of lanthanides(III) and curium(III) in the complexes extracted with purified Cyanex301, Cyanex302 and Cyanex272

Summary The hydration number of lanthanides, Ln(III) (Ln = Sm, Eu, Tb, Dy), and Cm(III) in the extracted complexes with purified Cyanex301, Cyanex302 and Cyanex272 was investigated using time-resolved laser-induced fluorescence spectroscopy (TRLFS) and FT-IR spectroscopy. The results, in conjunction with the previous results on the Ln(III) and Am(III) complexes, provide insight into the composition of the extracted complexes. No difference has been observed in the hydration number or the composition between the Ln(III) and Cm(III) complexes with Cyanex302 or Cyanex272. The extracted complexes of Ln(III) and Cm(III) with Cyanex302 have the formula, ML(HL 2 ) 2 · n H 2 O, where L stands for the anion of Cyanex302 and n =3-5. No water molecules are found in the first coordination shell of Ln(III) or Cm(III) complexes with Cyanex272. In contrast to the extraction with Cyanex302 or Cyanex272, the composition of the Ln(III) complexes is different from that of the Cm(III) complex in the extraction with Cyanex301. The Ln(III) complex with Cyanex301 has one or two H 2 O molecules with a molecular formula of LnL 3 ·2H 2 O or HLnL 4 ·H 2 O, where L stands for the anion of Cyanex301. However, the Cm(III) complex with Cyanex301 does not contain H 2 O with the molecular formula of HCmL 4 , in which only the 8 sulfur atoms from Cyanex301 coordinate to Cm(III). The results for Cm(III) agree with the previous data for Am(III) from EXAFS and IR measurements.