Spectroscopic and Electrochemical Analyses for Dysprosium Complexes In Potassium Bis(trifluoromethylsulfonyl)amide Melts

Abstract

The coordination states of multivalent dysprosium complexes of potassium bis(trifluoromethylsulfonyl) amide (K[NTf2]) were investigated by Raman spectroscopy. The concentration dependence of the deconvoluted Raman spectra was investigated for 0.23−0.45 mol kg−1 Dy(III), and a mixed sample of Dy(II)/Dy(III) (molar ratio 1/3), in K[NTf2]. Using conventional analysis, the solvation number, n, of the dysprosium complexes was determined to be 4.12 for Dy(II) and 5.09 for Dy(III). The electrochemical behavior of [DyIII(NTf2)5]2– in K[NTf2] melts was also investigated in this study. It is speculated that the first reduction peak at approximately +2.24 V probably corresponds to the formation of [DyII(NTf2)4]2–. Electrochemical analysis revealed that the reduction peak of [DyIII(NTf2)5]2– at approximately +0.81 V at 483 K is based on an electrodeposition reaction from [DyIII(NTf2)5]2– to Dy(0). The diffusion coefficient and activation energy of [DyIII(NTf2)5]2– in K[NTf2] melts were measured in the range 473–493 K by semi-integral and semi-differential analyses. Furthermore, the nucleation behavior of [DyIII(NTf2)5]2– was evaluated using chronoamperometry. The results indicated that the nucleation mechanism of Dy nuclei changed from instantaneous to progressive nucleation when the overpotential became more negative than the deposition potential of Dy(0). The electrodeposits were identified as mostly the metallic state by X-ray photoelectron spectroscopy.

Voltammetric Behaviour and Electrodeposition of Samarium in 1-Butyl-1-methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide Ionic Liquid

“…The original peak at 741 cm −1 is due to "free" [ ] − Tf N 2 anion and the new band at 752 cm −1 is attributed to [ ] − Tf N 2 anion bounded to the center of Sm 3+ cation as observed for other lanthanides ions in ionic liquid systems. [33][34][35][36] To obtain some quantitative information in the dissolution of the samarium salt in the ionic liquid, Raman spectra of 0.3 M, 0.4 M and 0.5 M of Sm(Tf 2 N) 3 in [BMP][Tf 2 N] were acquired within the range of 720-780 cm −1 and the bands at 741 cm −1 and 752 cm −1 are deconvoluted and fitted with two Voigt functions as shown in Fig. 3.…”

“…However, the obtained solvation number of 4 for Sm 3+ in the present study is closer to the calculated value of 5 for Nd 3+ and Dy 3+ in a Tf 2 N-based ionic liquid. 34,35,37,42 [ ] − Tf N 2 is known to act as a bidentate ligand with its two oxygen atoms coordinating to the central Sm 3+ . Table SII summarizes some reported Ln complexes in both ionic liquids and neutral ligandbased ionic liquid systems.…”

Electrochemical and spectroscopic analyses for praseodymium complexes in potassium bis(trifluoromethylsulfonyl)amide melts

“…We also showed that the solvation structures and the electrochemical behaviors of the trivalent Nd(III) and Dy(III) have been investigated in our previous study [7,8] in order to elucidate the mechanism of electrodeposition. However, there was no information on the detailed solvation conformations of Pr(III) in K[NTf2] melts.…”

“…Environmentally, LTMS is stable compared to organic reagents and prevents the spread of harmful degradation products, as LTMS can be recycled back into the acid production cycle and re-used as an electrolytic bath. Recent work has revealed the electrochemical and nucleation behavior of Nd(III) [7] and Dy(III) [8] within the K[NTf2] melts. However, there was no information available on the diffusion and electrodeposition behavior of Pr(III) in K[NTf2] melts.…”

“…The D values of Nd(III) and Dy(III)[7,8] in K[NTf2] from our previous investigations are also shown to allow comparison. Raman spectroscopy was used to determine the coordination state of [Ln(III) (cis-NTf2)5] 2-(Ln=Nd, Dy) in K[NTf2] melts for Nd(III) and Dy(III)[7,8]. The similar coordination state of [Pr(III) (cis-NTf2)5] 2-is predictable, because the diffusion coefficient value of Pr(III) was very close to that of Nd(III) in K[NTf2] of similar magnitude.…”