The viscosity (η) and electrical conductivity (κ) of ionic liquids are, next to the melting point, the two key properties of general interest. The knowledge of temperature-dependent η and κ data before their first synthesis would permit a much more target-oriented development of ionic liquids. We present in this work a novel approach to predict the viscosity and electrical conductivity of an ionic liquid without further input of experimental data. For the viscosity, only some basic physical observables like the Gibbs solvation energy (ΔG(solv)(*,∞)), which was calculated at the affordable DFT-level (RI-)BP86/TZVP/COSMO, the molecular radius, calculated from the molecular volume V(m) of the ion volumes, and the symmetry number (σ), according to group theory, are necessary as input. The temperature dependency (253-373 K) of the viscosity (4-19000 mPa s) was modeled by an Arrhenius approach. An alternative way, which avoids the deficits of the Arrhenius relation by a series expansion in the exponential term, is also presented. On the basis of their close connection, the same set of parameters is suitable to describe the electrical conductivity as well (238-468 K, 0.003-193 mS/cm). Nevertheless, more elegant alternatives like the usage of the Stokes-Einstein/Nernst-Einstein relation or the Walden rule are highlighted in this work. During this investigation, we additionally found an approach to predict the dielectric constant ε* of an ionic liquid at 298 K by using V(m) and ΔG(solv)(*,∞) between ε* = 9 and 43.

A series of bis(trifluoromethylsulfonyl)imide ionic liquids (ILs) with classical as well as mildly functionalized cations was prepared and their viscosities and conductivities were determined as a function of the temperature. Both were analyzed with respect to Arrhenius, Litovitz and Vogel-Fulcher-Tammann (VFT) behaviors, as well as in the context of their molecular volume (V(m)). Their viscosity and conductivity are highly correlated with V(m)/T or related expressions (R(2) ≥0.94). With the knowledge of V(m) of new cations, these correlations allow the temperature-dependent prediction of the viscosity and conductivity of hitherto unknown, non- or mildly functionalized ILs with low error bars (0.05 and 0.04 log units, respectively). The influence of the cation structure and mild functionalization on the physical properties was studied with systematically altered cations, in which V(m) remained similar. The T(o) parameter obtained from the VFT fits was compared to the experimental glass temperature (T(g)) and the T(g)/T(o) ratio for each IL was calculated using both experimental values and Angell's relationship. With Walden plots we investigated the IL ionicity and interpreted it in relation to the cation effects on the physical IL properties. We checked the validity of these V(m)/T relations by also including the recently published variable temperature viscosity and conductivity data of the [Al(OR(F))(4)](-) ILs with R(F) =C(H)(CF(3))(2) (error bars for the prediction: 0.09 and 0.10 log units, respectively).

It is known that nano- or microcrystalline aluminium may be electrodeposited from mixtures of AlCl(3) and the ionic liquids 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)amide ([BMP]Tf(2)N) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)amide ([EMIm]Tf(2)N), and that two phases form with higher formal concentrations of AlCl(3) (at 1.6 mol L(-1) (x(Al)=0.33) and 2.5 mol L(-1) (x(Al)=0.39), respectively). This account analyzes the hitherto unknown molecular nature of these mixtures by a detailed experimental (multinuclear NMR and Raman spectroscopies) and theoretical study (BP86/TZVP DFT calculations, including COSMO solvation energies). The addition of AlCl(3) to the two liquids first leads to complexation with [Tf(2)N](-) and then disproportionation of the initial [AlCl(x)(Tf(2)N)(y)](-) complexes give Al(Tf(2)N)(3) and [AlCl(4)](-). At high concentrations of AlCl(3), the lower phase consists almost completely of Al(Tf(2)N)(3), whereas in the upper phase [AlCl(4)](-) is the dominant species. Electrodeposition of aluminium in the upper phase occurs from mixed AlCl(x)(Tf(2)N)(y) species, most likely from [AlCl(2)(Tf(2)N)(2)](-) formed in small concentrations at the phase boundary between the [AlCl(4)](-) and the Al(Tf(2)N)(3) layers. All the findings are supported by DFT calculations as well as an X-ray crystal structure determination of Al(Tf(2)N)(3). The latter was separated from the mixture by sublimation on a preparative scale. It was independently prepared from AlEt(3) and HNTf(2) and fully characterized. Moreover, the ionic liquids [BMP]AlCl(4) (m.p. 74 degrees C) and [EMIm]AlCl(4) (m.p. -7 degrees C), which mainly form the upper layer in the biphasic regime, were independently prepared and also fully characterized.

Based on temperature (T) dependent crystal structure data of seven organic salts, a radii-based scheme for the calculation of the van der Waals volume (V(vdw)) is analyzed. The obtained volumes (V(vdw,r), r=radius-based) are nearly T independent. An ion volume partitioning scheme is proposed by fixing the anion volumes of [Cl](-), [Br](-), [I](-), [BF(4)](-), [PF(6)](-), [OTf](-) and [NTf(2)](-). The van der Waals volumes (V(vdw,r) (+/-)) of 48 ions are established, with low standard deviations (0.2-3.6 Å(3), 0.1-4.5 % of V(vdw,r) (+/-)). The ion volumes are independent of the counterion and one crystal structure already suffices for their derivation. Correlations of the viscosity with V(vdw,r) via a Litovitz ansatz and our recently derived Arrhenius-type approach prove that these volumes are suitable for the volume-based description and prediction of IL properties. The corresponding correlation coefficient for the latter is R(2)=0.86 for 40 ILs (354 data points) in the T range of 253-373 K.

A new Li salt with views to success in electrolytes is synthesized in excellent yields from lithium borohydride with excess 2,2,2-trifluorethanol (HOTfe) in toluene and at least two equivalents of 1,2-dimethoxyethane (DME). The salt Li[B(OTfe)4 ] is obtained in multigram scale without impurities, as long as DME is present during the reaction. It is characterized by heteronuclear magnetic resonance and vibrational spectroscopy (IR and Raman), has high thermal stability (Tdecomposition >271 °C, DSC) and shows long-term stability in water. The concentration-dependent electrical conductivity of Li[B(OTfe)4 ] is measured in water, acetone, EC/DMC, EC/DMC/DME, ethyl acetate and THF at RT In DME (0.8 mol L(-1) ) it is 3.9 mS cm(-1) , which is satisfactory for the use in lithium-sulfur batteries (LiSB). Cyclic voltammetry confirms the electrochemical stability of Li[B(OTfe)4 ] in a potential range of 0 to 4.8 V vs. Li/Li(+) . The performance of Li[B(OTfe)4 ] as conducting salt in a 0.2 mol L(-1) solution in 1:1 wt % DME/DOL is investigated in LiSB test cells. After the 40th cycle, 86 % of the capacity remains, with a coulombic efficiency of around 97 % for each cycle. This indicates a considerable performance improvement for LiSB, if compared to the standard Li[NTf2 ]/DOL/DME electrolyte system.

An appealing couple: The unprecedented insertion of the nitrosonium cation into a tetrahedral edge of white phosphorus forms the highly reactive [P4NO]+ cation (see picture). The synthesis, characterization, and applications are discussed, and NO2[Al(OC(CF3)3)4] is presented as an easily synthesized oxidant.

The crystal structures of nine organic salts of which seven are ionic liquids (ILs), comprising imidazolium, ammonium, piperidinium, and sulfonium cations, were determined. The occurrence of short contacts in the compounds' crystal structures was quantified with Hirshfeld surface analyses. Temperature dependent crystal structure data for several organic salts were recorded systematically in the temperature range from 100 K to room temperature. The thermal behavior of the cell constants was linear and anisotropic for almost all compounds. The accuracy of the molecular volume (Vm) – the key quantity in volume based thermodynamics (VBT) – was investigated in terms of its temperature dependency and the statistical error of the constituent ion volumes (Vm+/–). The former effect turned out to be at most on the same order of magnitude as the errors of Vm+/–. The same analysis was applied to the recently proposed new internally consistent molecular ion volumes (Vm, new+/–). For this purpose, a set of overall 40 Vm, new+/– values of typical polyatomic ions constituting ILs was established. In general, it is recommended to use as many salts as possible and as many temperature dependent data as available for the derivation of new Vm+/– and Vm, new+/– values.

The synthesis and characterization of Li[O2P{OCH(CF3)2}2] (1) was investigated together with a new synthesis for Li[O2P(OCH2CF3)2] (2). The electrochemical properties of both lithium bis(fluoroalkyl)phosphates were investigated. Compound 2 was prepared by deprotonation of the conjugate acid HO(O)P(OCH2CF3)2 (3), of which the crystal structure was solved. Lithium bis(fluoroalkyl)phosphates 1 and 2 were used to prepare gel electrolytes on the basis of a coordination network held together solely by ionic interactions between the lithium ions and the anions. The preparation of the gel electrolytes produced with 2 and their properties were explored.