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Ionic liquids (ILs) are attractive alternatives to water, high temperature molten salts or conventional organic solvents for electrodeposition of technologically important metals. Designing ILs containing functional groups specifically targeted to interact with or even chelate metals, such as carboxylate, may increase the metal solubility and affect thermodynamic and electrochemical properties. This paper reports the synthesis and characterization of three ionic liquids comprised of one or two tetra-alkyl phosphonium cations paired with a hydrogen oxalate or oxalate anion, with the general formula [(PRRRR′)x][C2O4H2−x], R = 4,6 and R′ = 4, 14. These compounds were characterized by 1H, 13C, 31P NMR, and Raman spectroscopy. Electrochemical windows, electrical conductivities, densities and viscosities were also determined experimentally. Thermal gravimetric analysis (TGA) revealed decomposition temperatures above 200 °C and differential scanning calorimetry (DSC) analysis revealed that the two [(P66614)x][C2O4H2−x] salts have similar glass transition temperatures while [(P4444)2][C2O4] has a melting point above room temperature. Raman and powder X-ray diffraction spectroscopy confirm that Nd2O3 dissolves and complexes with [P66614][C2O4].

The carboxyl-functionalized phosphonium ionic liquid (IL), [HCTMP][Tf(2)N], enabled the directed nucleation of monomeric or dimeric uranyl(vi) compounds. This new IL is the first carboxyl-functionalized IL which is liquid at room temperature and exhibits a wider electrochemical window and lower melting point than its ammonium analogue.

A series of novel ionic liquids (ILs) based on N, N'- dialkylimidazolium, tetra-alkylphosphonium and dialkylpyrrolidinium cations paired with two aprotic heterocyclic anions (AHAs) were synthesized in the present study. In addition, lithium salts of the corresponding anions were prepared. Physicochemical and electrochemical properties of the neat ILs and their mixtures with the lithium salts at various concentrations were systematically measured from 283.15K to 343.15K at atmospheric pressure, including density (ρ), viscosity (η) and electrical conductivity (σ). The empirical Vogel-Fulcher-Tammann (VFT) was used to analyze the experimental viscosities and electrochemical conductivities. Furthermore, the Walden plot behavior of the pure ILs and ILs doped with lithium salts were investigated. The results provide some insight into the strength of the association between Li+ and the different anions. Consequently, the ILs with low viscosity and good conductivities are promising electrolytes candidates to be used in electrochemical applications.

A diarylamino-substituted N-methyl tetrahydrosalen (salan) ligand, (An2N)LH(2), is prepared in four steps and overall 53% yield from 5-bromosalicylaldehyde, with the key step a palladium-catalysed Hartwig-Buchwald amination of the tert-butyldimethylsilyl-protected 5-bromo-N-methylsalan ligand. Reaction of (An2N)LH(2) or its bromo analogue with Ti(O(i)Pr)(4) or TiF(4) results in metalation of the ligand. The isopropoxide groups are readily exchanged with α- or β-hydroxyacids to form chelated complexes. X-ray crystallography and NMR spectroscopy indicate that the salan ligands are quite flexible, with (An2N)LTiF(2), for example, showing four stereoisomers in its (19)F NMR spectrum. The major stereoisomer of (salan)Ti(X)(Y) depends principally on the trans influence of the X and Y groups. Complexes of (An2N)L show two reversible, closely spaced redox couples at approximately + 0.1 V vs. ferrocene/ferrocenium, and a second set of two closely spaced redox couples at ~ + 0.8 V vs. Fc/Fc(+).