An Electrochemical and Spectroscopic Study of Nd(III) and Pr(III) Coordination in the 1-Butyl-1-methylpyrrolidinium Bis(trifluoromethylsulfonyl)imide Ionic Liquid Containing Chloride Ion

Abstract

The coordination and accessible oxidation states of Nd and Pr were investigated in 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BuMePyroTf2N) by using electronic absorption spectroscopy, cyclic staircase voltammetry, and controlled potential coulometry. These experiments were carried out in the neat ionic liquid (IL) and in the IL containing free Cl(-) from the dissolution of BuMePyroCl. The electrolytic dissolution of Ln = Nd and Pr metal in this IL produces only the respective Ln(3+) ions. These trivalent species can be reduced to Ln(2+), but the resulting divalent species exhibit only transient stability, undergoing rapid disproportionation to Ln(3+) and Ln(0). The intensity of the hypersensitive (4)G5/2 ← (4)I9/2 electronic transition for Nd(3+) dissolved in the IL was substantially larger than it was in noncoordinating solvents such as aqueous HClO4, indicating moderate interactions between Nd(3+) and Tf2N(-) ions, probably resulting in anionic species such as [Nd(Tf2N)x]((x-3)-). The addition of Cl(-) to [Ln(Tf2N)x]((x-3)-) solutions results in the precipitation of LnCl3(s) (s = solid). The LnCl3(s) redissolves to give the octahedral complex [LnCl6](3-) as the Cl(-) concentration is raised further. In the IL containing excess chloride, the (3)P0 ← (3)H4 transition for [PrCl6](3-) exhibits ligand-mediated pseudohypersensitive behavior.

Electrochemical and Spectroscopic Study of EuIII and EuII Coordination in the 1‐Ethyl‐3‐methylimidazolium Bis(trifluoromethylsulfonyl)imide Ionic Liquid

“…[11] In contrast,I Lw ere shownt ob eg ood solvents for the stabilization and study of the oxidation states + II and + IV for Ln. [12][13][14][15] Specifically,E u II can be stabilized in aqueous solutions thanks to cyclic ligands such as cryptands or analogues [16] whereasi nn onaqueousm edia, fully dissolved stablef orms of Ln II can be observed. [17,18] The electrochemical behavior of the Eu III /Eu II redoxc ouple was extensively studiedi nawide range of IL [14,[19][20][21][22][23][24][25][26][27] and its apparent standard potential was found to vary between0and À1.0 Vv ersus ferrocenium/ferrocene (Fc + /Fc) reference, depending on the medium.…”

“…For instance, lanthanide (Ln) elements are usually found at an oxidation state of +III in aqueous solution, and oxidation states +II (Eu, Sm, Yb) or +IV (Ce, Pr, Tb) require complexation to remain stable in aqueous solution [11] . In contrast, IL were shown to be good solvents for the stabilization and study of the oxidation states +II and +IV for Ln [12–15] . Specifically, Eu II can be stabilized in aqueous solutions thanks to cyclic ligands such as cryptands or analogues [16] whereas in nonaqueous media, fully dissolved stable forms of Ln II can be observed [17, 18] .…”

A hexanuclear Nd (III) complex derived from a Schiff base with significant antitumor and antifungal activity

“…Lanthanide-based complexes are currently being investigated extensively for a variety of functionalities and applications, such as optical probes, medicine, microelectronics, and others. [1][2][3][4][5][6][7][8][9][10][11] However, only limited kinds of metal complexes can be used as the anticancer drug in clinic among which platinum (II) and ruthenium (III) complexes are the most popular studied. Cancer patients undergoing chemotherapy usually possess a chance of 20% suffering Candida infection, and most antitumor drugs show no antifungal activities.…”

Electrodeposition of Pt and Gd from the Same Ionic Liquid

“…A number of reports have addressed the electrochemical deposition of rare earth metals from ionic liquids (29)(30)(31)(32)(33)(34)(35). The electrodeposition of RE metal from RE 3+ ions is often not a single step process but involves the intermediate formation of a lower valency species (36)(37)(38) which is stable for some RE/IL combinations, and disproportionates to metal and RE 3+ for others (36)(37)(38)(39). Especially in butylmethylpyrrolidinium bistrifluoromethylsulfonylimide (BMP TFSI), surface passivation instead of metal deposition was observed for a number of RE metals, like Ce, Pr and Nd (36,37).…”

“…The electrodeposition of RE metal from RE 3+ ions is often not a single step process but involves the intermediate formation of a lower valency species (36)(37)(38) which is stable for some RE/IL combinations, and disproportionates to metal and RE 3+ for others (36)(37)(38)(39). Especially in butylmethylpyrrolidinium bistrifluoromethylsulfonylimide (BMP TFSI), surface passivation instead of metal deposition was observed for a number of RE metals, like Ce, Pr and Nd (36,37). Many studies on RE metal deposition were characterized by the absence of a corresponding dissolution peak (30,33,34,40), which is explained by slow charge transfer kinetics or reactions with residual moisture (33) or the ionic liquid (34).…”