Structural and Electrochemical Properties of YbIII in Various Ionic Liquids

✍ Scribed by Arash Babai; Slawomir Pitula; Anja-Verena Mudring

• Publisher: John Wiley and Sons
• Year: 2010
• Tongue: English
• Weight: 318 KB
• Volume: 2010
• Category: Article
• ISSN: 1434-1948
• DOI: 10.1002/ejic.201000323

✦ Synopsis

Abstract

Solvation and ligand exchange reactions of ytterbium(III) as a model for the late trivalent f‐elements have been studied in triflate and bistriflylamide ionic liquids (ILs) with the purpose of contributing to a wider understanding of f‐element organometallic catalysis, as well as separation and nuclear fuel reprocessing, in ILs. Using the compounds [C~4~mpyr]~3~[Yb(OTf)~6~] and [C~4~mpyr][Yb(Tf~2~N)~4~] [C~4~mpyr = N‐methyl‐N‐propylpyrrolidinium; OTf = triflate, trifluoromethanesulfonate; Tf~2~N = bistriflylamide, bis(trifluoromethanesulfonyl)amide] we were able to structurally characterize the local surroundings of Yb^3+^ in the ILs [C~4~mpyr][OTf] and [C~4~mpyr][Tf~2~N]unequivocally. The formation of [C~4~mpyr]~3~[Yb(OTf)~6~][C~4~mpyr][Tf~2~N] from a solution of Yb(Tf~2~N)~3~ in [C~4~mpyr][OTf] shows that the stronger coordinating OTf^–^ anion completely replaces the less Lewis basic Tf~2~N^–^ anion in the first coordination sphere of the lanthanide ion. As expected, such a ligand exchange could not be observed for Yb(OTf)~3~ in [C~4~mpyr][Tf~2~N]. The ion exchange in the lanthanide coordination sphere can be efficiently monitored by means of cyclic voltammetry (CV). CV measurements also indicate that Yb^3+^ adopts a mixed OTf^–^/Tf~2~N^–^ coordination environment when Yb(OTf)~3~ is dissolved in [C~4~mpyr][Tf~2~N]. The measured half‐wave potentials of the studied systems can be linked to the electron‐donor properties of the metal cation.