Structural Characterization of a Lanthanum Bistriflimide Complex, La(N(SO₂CF₃)₂)₃(H₂O)₃, and an Investigation of La, Sm, and Eu Electrochemistry in a Room-Temperature Ionic Liquid, [Me₃NⁿBu][N(SO₂CF₃)₂]

Abstract

The reduction of selected lanthanide cations to the zerovalent state in the room-temperature ionic liquid [Me3N(n)Bu][TFSI] is reported (where TFSI = bistriflimide, [N(SO2CF3)2]-). The lanthanide cations were introduced to the melt as the TFSI hydrate complexes [Ln(TFSI)3(H2O)3] (where Ln = La(III), Sm(III) or Eu(III)). The lanthanum compound [La(TFSI)3(H2O)3] has been crystallographically characterized, revealing the first structurally characterized f-element TFSI complex. The lanthanide in all three complexes was shown to be reducible to the metallic state in [Me3N(n)Bu][TFSI]. For both the Eu and Sm complexes, reduction to the metallic state was achieved via divalent species, and there was an additional observation of the electrodeposition of Eu metal.

Lanthanides and Actinides in Ionic Liquids

“…The viscosity can be reduced by a proper choice for the anion, for instance, [Tf 2 N] -, and by making the alkyl chain not too long (six or less carbon atoms). 93 135 The quaternary arsonium salt showed the highest stability (from -3.4 to 2.6 V versus ferrocenium/ferrocene), followed by the phosphonium salt. It was shown by cyclic voltammetry that europium metal can be electrodeposited from these ionic liquids.…”

“…However, in dry ionic liquids or in ionic liquids with a low water content, the situation is different, and the -ligand acts as a bidentate ligand, and coordination occurs through an oxygen atom of each sulfonyl group. 93 Because of the additional coordination of three water molecules, the coordination number of the lanthanum(III) ion is nine. The coordination polyhedron can be described as a tricapped trigonal prism, and the three water molecules form the bottom triangular face of the trigonal prism.…”

Electrodeposition of Pt - Rare Earth Alloys as ORR Catalysts for Fuel Cells

“…However, due to the low deposition potential of rare-earth metals, aqueous electrolytes were not considered for these experiments. Therefore, other electrolytes, especially ionic liquids, were chosen as electrolyte, because they offer a wide electrochemical window (9) and in literature a successful deposition of selected pure rare-earth metals had been claimed (10)(11)(12)(13)(14)(15)(16). For La-deposition, a peak potential of -2.4 V vs Fc + /Fc was reported (12).…”

Europium‐Based Ionic Liquids as Luminescent Soft Materials

“…[5] Furthermore, ionic liquids offer the possibility of electrodeposition of the electropositive f elements themselves. [6] Thus, the investigation of f-element chemistry in ionic liquids is of relevance for various fields. [7] Examples of ionic liquids containing f elements are, to date, Na 13 [Ln(TiW 11 O 39 ) 2 ]·x H 2 O (x = 27-44) with f-element polyoxometallates of the Keggin type [8] and complex lanthanide thiocyanates [C 4 …”