Gas phase structure and conformational properties of trifluoroacetic anhydride, CF3C(O)OC(O)CF3

The geometric structure of trifluoroacetic anhydride, CF₃C(O)OC(O)CF₃, has been studied by gas electron diffraction (GED) and quantum chemical calculations (MP2 and B3LYP with 6-31G^* basis sets). The GED analysis results in a single conformer with synperiplanar orientation of the two CO bonds. This analysis, however, cannot discriminate between a planar equilibrium structure (C_2v symmetry) with large amplitude torsional motions around the OC bonds and a nonplanar equilibrium structure (C₂ symmetry) with a low barrier at the planar arrangement. An effective dihedral angle φ(COCO=18(4)° is obtained. Both quantum chemical methods predict a nonplanar equilibrium structure of C₂ symmetry and φ(COCO)=16.5° and 13.9°, respectively.     

The synthesis, structure and ethene polymerization activity of octahedral heteroligated (salicylaldiminato)(β-enaminoketonato)titanium complexes: The X-ray crystal structure of {3-Bu-2-(O)C6H3CHN(Ph)}{(Ph)NC(Me)C(H)C(Me)O}TiCl2

Treatment of the mono(salicylaldiminato)titanium complexes {3-Bu^t-2-(O)C₆H₃CHN(Ar)}TiCl₃(THF) (Ar = C₆H₅, 2,4,6-Me₃C₆H₂ or C₆F₅) with the potassium β-enaminoketonates (C₆H₅)NC(CH₃)C(H)C(R)OK (R = CH₃, CF₃) yielded the first examples of heteroligated (salicylaldiminato) (β-enaminoketonato)titanium dichloride complexes. The complex {3-Bu^t-2-(O)C₆H₃CHN(C₆H₅)}{(C₆H₅)NC(CH₃)C(H)C(CH₃)O}TiCl₂ was structurally characterized by X-ray diffraction and has an orientation with trans-O,O,cis-Cl,Cl, cis-N,N distorted octahedral geometry. These complexes polymerize ethene when activated with MAO; the highest productivity, 5650 kg PE (mol metal)⁻¹ h⁻¹ atm⁻¹, was afforded by {3-Bu^t-2-(O)C₆H₃CHN(C₆F₅)}{(C₆H₅)NC(CH₃)C(H)C(CF₃)O}TiCl₂ at 60 °C.     

Anodic oxidation of organometallic sandwich complexes using [Al(OC(CF3)3)4] or [AsF6] as the supporting electrolyte anion

Anodic voltammetry and electrolysis of the metallocenes ferrocene, ruthenocene, and nickelocene have been studied in dichloromethane containing two different fluorine-containing anions in the supporting electrolyte. The perfluoroalkoxyaluminate anion [Al(OC(CF₃)₃)₄]⁻ has very low nucleophilicity, as shown by its inertness towards the strong electrophile [RuCp₂]⁺ and by computation of its electrostatic potential in comparison to other frequently used electrolyte anions. The low ion-pairing ability of this anion was shown by the large spread in E_1/2 potentials (ΔE_1/2 = 769 mV) for the two one-electron oxidations of bis(fulvalene)dinickel. The hexafluoroarsenate anion [AsF₆]⁻, on the other hand, reacts rapidly with the ruthenocenium ion and is much more strongly ion-pairing towards oxidized bis(fulvalene)dinickel (ΔE_1/2 = 492 mV). In terms of applications of these two anions to the anodic oxidation of organometallic sandwich complexes, the behavior of [Al(OC(CF₃)₃)₄]⁻ is similar to that of other weakly-coordinating anions such as [B(C₆F₅)₄]⁻, whereas that of [AsF₆]⁻ is similar to the more traditional electrolyte anions such as [PF₆]⁻ and [BF₄]⁻. Additionally, the synthesis and crystal structure of [Cp₂Fe][Al(OC(CF₃)₃)₄] are reported.     

The reaction of photochemically generated CF3O radicals with CO

CF₃O₂CF₃ was photolyzed at 254 nm in the presence of CO in 760 torr N₂ or air at 296 K in a static reactor. In N₂, the products CF₃OC(O)C(O)OCF₃ and CF₃OC(O)O₂C(O)OCF₃ were detected by FTIR spectroscopy. In air, the only observed products were CF₂O and CO₂ and a chain process, initiated by CF₃O, was invoked for the conversion of CO to CO₂. From both product studies, a mechanism for the CF₃O initiated oxidation of CO was derived, involving the addition reaction CF₃O₂ + CO → CF₃OC(O). The rate constant for the reaction CF₃O + CO at 296 K at a total pressure of 760 torr air was determined to be k(CF₃O + CO) = (5.0 ± 0.9) × 10⁻¹⁴ cm³ molecule⁻¹ s⁻¹. © 1997 John Wiley & Sons, Inc.     

Fluorinated phosphorus compounds: Part 10. Bis(fluoroalkyl) S-alkyl phosphorothiolates and tris(fluoroalkyl) phosphorothionates

Treatment of bis(fluoroalkyl) phosphites (R_FCH₂O)₂P(O)H, where R_F was CF₃ or C₂F₅ with sulfur in pyridine at 80 °C gave salts of structure [(R_FCH₂O)₂P(O)SH]NC₅H₅ in 90 and 88% yield, respectively. The salts reacted with alkyl iodides in acetonitrile at 50 °C to furnish bis(fluoroalkyl) S-alkyl phosphorothiolates (R_FCH₂O)₂P(O)SR, where R was Me, Et, n- and i-Pr (when R_F = CF₃) and Me (when R_F = C₂F₅). Yields ranged from 21 to 57%. Bis(trifluoroethyl) S-methyl phosphorothiolate (CF₃CH₂O)₂P(O)SMe underwent fluorination by silver(I) fluoride in acetonitrile at room temperature to yield the phosphorofluoridate (CF₃CH₂O)₂P(O)F in 75% yield. Tris(fluoroalkyl) phosphorothionates (R_FCH₂O)₃P = S, where R_F was CF₃, C₂F₅ and C₃F₇, were prepared in 30-34% yield by heating the tris(fluoroalkyl) phosphites (R_FCH₂O)₃P and sulfur to 200 °C in a sealed tube for 8 h.     

Thermal decomposition of Cu(NO3)2·3H2O at reduced pressures

Thermolysis of Cu(NO₃)₂·3H₂O is studied by means of XRD analysis in situ and mass spectral analysis of the gas phase at P=1/10 Pa at low heating rate. It is shown that stage I of the dehydration (40-80 °C) results in the consecutive appearance of crystalline Cu(NO₃)₂·2.5H₂O and Cu(NO₃)·H₂O. Anhydrous Cu(NO₃)₂ formed during further dehydration at 80-110 °C is moderately sublimed at 120-150 °C. Dehydration is accompanied by thermohydrolysis, leading to the appearance of Cu₂(OH)₃NO₃ and gaseous H₂O, HNO₃, NO₂, and H₂O. The higher pressure in the system, the larger amount of thermohydrolysis products is observed. The formation of the crystalline intermediate CuO_x(NO₃)_y was observed by diffraction methods. Final product of thermolysis (CuO) is formed at 200-250 °C.     

Exchange reactions between O-nitrosobis(trifluoromethyl)hydroxylamine and M(CF3)3 (M = P,As and Sb)

O-Nitrosobis(trifluoromethyl)hydroxylamine gives novel reactions with tris(trifluoromethyl)-phosphine, -arsine and -stibine to affford mainly the corresponding bis(trifluoromethyl)nitroxol derivatives. Tris(trifluoromethyl) phosphine affords (CF₃)₂NOP(O)(CF₃)₂ and (CF₃)₂NNO. Tris(trifluoromethyl) arsine also gives (CF₃)₂NNO in high yield, together with smaller amounts of (CF₃)₂NOAs(CF₃)₂, CF₃NCF₂, COF₂ and a polymeric white solid. With tris(trifluoromethyl)stibine, no oxidation nor addition reactions occurred. Instead, [(CF₃)₂NO]₃Sb and [(CF₃)NO]₂SbCF₃ were obtained in high yields. The stoichiometry of the reactions suggests that the additional amounts of bis(trifluoromethyl)nitroxyl groups bonded to antimony are derived from the trifluoromethyl groups bonded to antimony. Mechanisms to rationalise these reactions are proposed.     

Sol-gel synthesis and characterization of LiNO3-Al2O3 composite solid electrolyte

Composite solid electrolytes in the system (1 − x)LiNO₃-xAl₂O₃, with x = 0.0-0.5 were synthesized by sol-gel method. The synthesis carried out at low temperature resulted in voluminous and fluffy products. The obtained materials were characterized by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy/energy dispersive X-ray, Fourier transform infrared spectroscopy and AC impedance spectroscopy. Structural analysis of the samples showed base centred cell type of point lattice of LiNO₃ for the composite samples with x = 0.1-0.2 and body centred cell for the sample with x = 0.3. A trace amount of α-LiAlO₂ crystal phase was also present in these composite samples. The thermal analysis showed that the samples were in a stable phase between 48 °C and 230-260 °C. Morphological analysis indicated the presence of amorphous phase and particles with sizes ranging from micro to nanometre scale for the composite sample with x = 0.1. The conductivities of the composites were in the order of 10⁻³ and 10⁻² S cm⁻¹ at room temperature and 150 °C, respectively.     

A new catalytic system for the copolymerization of dicyclopentadiene with CO: PdCl2/phen/M(CF3SO3)n

A new three-component catalytic system, PdCl₂/phen/M(CF₃SO₃)_n, was studied in the copolymerization of dicyclopentadiene (DCPD) with CO. It was found that the PdCl₂/phen/CF₃SO₃H catalytic system gave a very low catalytic activity, and the PdCl₂/phen/M(CF₃SO₃)_n catalytic system exhibited high activity when M(CF₃SO₃)_n was introduced instead of CF₃SO₃H. The resultant cooligomer was analyzed using various techniques such as FT-IR, ¹H NMR, ¹³C NMR, DSC and TGA. The results indicated that the copolymer was a polyspiroketal (PS) of CO and DCPD. Due to the tension of the ring of DCPD, the degree of copolymerization is low and the degree of crystallinity is also not high. The effects of ligands, M(CF₃SO₃)_n, solvents, 1,4-benzoquinone/PdCl₂ molar ratio, and temperatures on the copolymerization have been discussed in detail. The results showed that this novel catalytic system exhibited highly efficient activity, especially when 1,10-phenanthroline (phen) was used as ligand and Cu(CF₃SO₃)₂ was used as cocatalyst. The corresponding reaction rate was 49 000 g PS/molPd h when the reaction was carried out at 60 °C and 3.0 MPa of CO. The weight average molecular weight (M_w) and the number average molecular weight (M_n) of the resultant cooligomer were 1180 g/mol and 564 g/mol, respectively.     

Thermal decomposition of trifluoromethoxycarbonyl peroxy nitrate,CF3OC(O)O2NO2

The thermal decomposition of trifluoromethoxycarbonyl peroxy nitrate, CF₃OC(O)O₂NO₂, has been studied between 278 and 306 K at 270 mbar total pressure using He as a diluent gas. The pressure dependence of the reaction was also studied at 292 K between 1.2 and 270 mbar total pressure. The rate constant reaches its high‐pressure limit at 70 mbar. The first step of the decomposition leads to CF₃OC(O)O₂ and NO₂ formation, that is, CF₃OC(O)O₂NO₂ + M ? CF₃OC(O)O₂ + NO₂ + M (k₁, k_?1). Reaction (?1) was prevented by adding an excess of NO that reacts with the peroxy radical intermediate and leads to carbonyl fluoride (CF₂O), carbon dioxide (CO₂), nitrogen dioxide (NO₂), and small quantities of CF₃OC(O)O₂C(O)OCF₃. The kinetics of reaction (1) was determined by following the loss of CF₃OC(O)O₂NO₂ via IR spectroscopy. The temperature dependence of the decomposition follows the equation k₁(T) = 1.0 × 10¹⁶ e^{?((111±3)/(RT))} for the exponential term expressed in kJ mol^?1. The values obtained for the kinetic parameters such as k₁ at 298 K, the activation energy (E_a), and the preexponential factor (A) are compared with literature data for other acyl peroxy nitrates. The atmospheric thermal stability of CF₃OC(O)O₂NO₂ and its dependence with altitude is discussed. © 2008 Wiley Periodicals, Inc. Int J Chem Kinet 40: 831–838, 2008     

A rare multi-coordinate tellurite, NH4ATe4O9·2H2O (ARb or Cs): The occurrence of TeO3, TeO4, and TeO5 Polyhedra in the same material

Two new tellurites, NH₄RbTe₄O₉·2H₂O and NH₄CsTe₄O₉·2H₂O have been synthesized and characterized. The compounds were synthesized hydrothermally, in near quantitative yields, using the alkali metal halide, TeO₂, and NH₄OH as reagents. The iso-structural materials exhibit layered, two-dimensional structural topologies consisting of TeO_x (x=3, 4, or 5) polyhedra separated by NH₄⁺, H₂O, Rb⁺ or Cs⁺ cations. Unique to these materials is the presence of TeO₃, TeO₄, and TeO₅ polyhedra. Thermogravimetric and infrared spectroscopic data are also presented. Crystal data: NH₄RbTe₄O₉·2H₂O: Monoclinic I2/a (no. 15), a=18.917(3) Å, b=6.7002(11) Å, c=21.106(5) Å, β=101.813(2)°, V=2618.5(9) Å³, Z=8; NH₄CsTe₄O₉·2H₂O: Monoclinic I2/a (no. 15), a=18.9880(12) Å, b=6.7633(4) Å, c=21.476(2) Å, β=102.3460(10)°, V=2694.2(3) Å³, Z=8.     

Reactions of Trifluoronitrosomethane with bistrifluoromethylphosphorus compounds, (CF3)2PX (where x = H,Cl, CF3)

Trifluoronitrosomethane reacts with bis(trifluoromethyl)phosphine to give (CF₃)₂P(O)N(OH)CF₃ and a small amount of (CF₃)₂NOH. On the other hand, the reactions with tris(trifluoromethyl)phosphine and bis(trifluoromethyl)chlorophosphine afford (CF₃)₂NOP(O)CF₃N(CF₃)₂ and (CF₃)₂NP(O)(CF₃)Cl respectively. Isomerisation of

may be involved as found for the isomerisation of the phosphine, (CF₃)₂NOP(CF₃)₂, to the phosphoryl compound, (CF₃)₂NP(O)(CF₃)₂. Mechanisms for the above reactions are discussed.     

Formation, sintering, and electrical conductivity of perovskite Sm(Cr1−xMgx)O3 (0?x?0.23) prepared by the hydrazine method

The presence of SmCrO₄ is experimentally established. In Mg²⁺-substituted SmCrO₃, single-phase perovskite Sm(Cr_1−xMg_x)O₃, where x=0-0.23, are formed at ∼830°C by decomposition of Sm(Cr_1−xMg_x)O₄ which crystallizes at 530-570°C from amorphous materials prepared by the hydrazine method. Sm(Cr_1−xMg_x)O₃ solid solution powders consisting of submicrometer-size particles are sinterable; dense materials can be fabricated by sintering for 2 h at 1700°C in air. The relative densities, grain sizes, and electrical conductivities increase with increased Mg²⁺ content. Sm(Cr_0.77Mg_0.23)O₃ materials exhibit an excellent direct current electrical conductivity of 2.2×10³ S m⁻¹ at 1000°C.     

Synthesis and Properties of CF3(OCF3)CH‐Substituted Arenes and Alkenes†

A silver‐mediated oxidative trifluoromethylation of easily accessible α‐trifluoromethyl alcohols with TMSCF₃ was developed to access novel CF₃(OCF₃)CH‐containing compounds. Deprotonation of CF₃(OCF₃)CH‐substituted arenes afforded synthetically useful CF₃O‐substituted gem‐difluoroalkenes. Furthermore, evaluation of the lipophilicities (log P) indicated that CH(OCF₃)CF₃ is more lipophilic than the common fluorinated motifs such as CF₃, OCF₃, and SCF₃, thus rendering the CH(OCF₃)CF₃ motif appealing in drug discovery.     

Conservation of [(C2H4NH3)3N]2·(ZrF7)2·H2O layers during the topotactic dehydration of [(C2H4NH3)3N]2·(ZrF7)2·9H2O

Tren amine cations [(C₂H₄NH₃)₃N]³⁺ and zirconate or tantalate anions adopt a ternary symmetry in two hydrates, [H₃tren]₂·(ZrF₇)₂·9H₂O and [H₃tren]₆·(ZrF₇)₂·(TaOF₆)₄·3H₂O, which crystallise in R32 space group with a_H = 8.871 (2) Å, c_H = 38.16 (1) Å and a_H = 8.758 (2) Å, c_H = 30.112 (9) Å, respectively. Similar [H₃tren]₂·(MX₇)₂·H₂O (M = Zr, Ta; X = F, O) sheets are found in both structures; they are separated by a water layer (O_w(2)-O_w(3)) in [H₃tren]₂·(ZrF₇)₂·9H₂O. Dehydration of [H₃tren]₂·(ZrF₇)₂·9H₂O starts at room temperature and ends at 90 °C to give [H₃tren]₂·(ZrF₇)₂·H₂O. [H₃tren]₂·(ZrF₇)₂·H₂O layers remain probably unchanged during this dehydration and the existence of one intermediate [H₃tren]₂·(ZrF₇)₂·3H₂O hydrate is assumed. O_w(1) molecules are tightly hydrogen bonded with -NH₃⁺ groups and decomposition of [H₃tren]₂·(ZrF₇)₂·H₂O occurs from 210 °C to 500 °C to give successively [H₃tren]₂·(ZrF₆)·(Zr₂F₁₂) (285 °C), an intermediate unknown phase (320 °C) and ZrF₄.     

Synthesis, crystal structure and thermal behavior of Sr3B2SiO8 borosilicate

Single crystals of Sr₃B₂SiO₈ were obtained by solid-state reaction of stoichiometric mixture at 1200 °C. The crystal structure of the compound has been solved by direct methods and refined to R1=0.064 (wR=0.133). It is orthorhombic, Pnma, a=12.361(4), b=3.927(1), c=5.419(1) Å, V=263.05(11) Å³. The structure contains zigzag pseudo-chains running along the b axis and built up from corner sharing (Si,B)−O polyhedra. Boron and silicon are statistically distributed over one site with their coordination strongly disordered. Sr atoms are located between the chains providing three-dimensional linkage of the structure.The formation of Sr₃B₂SiO₈ has been studied using annealing series in air at 900-1200 °C. According powder XRD, the probe contains pure Sr₃B₂SiO₈ over 1100 °C. The compound is not stable below 900 °C. In the pseudobinary Sr₂B₂O₅-Sr₃B₂SiO₈ system a new series of solid solutions Sr_3−xB₂Si_1−xO_8−3x (x=0-0.9) have been crystallized from melt. The thermal behavior of Sr₃B₂SiO₈ was investigated using powder high-temperature X-ray diffraction (HTXRD) in the temperature range 20-900 °C. The anisotropic character of thermal expansion has been observed: α_a= −1.3, α_b=23.5, α_c=13.9, and α_V=36.1×10⁻⁶ °C⁻¹ (25 °C); α_a= −1.3, α_b=23.2, α_c=5.2, and α_V=27.1×10⁻⁶ °C⁻¹ (650 °C). Maximal thermal expansion of the structure along of the chain direction [0 1 0] is caused by the partial straightening of chain zigzag. Hinge mechanism of thermal expansion is discussed.     

Synthesis, structure, and characterization of hybrid materials: [Ce(H2O)]2[O2C(CH2)2CO2]3 and [Sm(H2O)]2[O2C(CH2)2CO2]3·H2O

The rare-earth dicarboxylate hybrid materials [Ce(H₂O)]₂[O₂C(CH₂)₂CO₂]₃ ([Ce(Suc)]) and [Sm(H₂O)]₂[O₂C(CH₂)₂CO₂]₃·H₂O ([Sm(Suc)]) have been hydrothermally synthesized (200°C, 3 days) under autogenus pressure. [Ce(Suc)] is triclinic, a=7.961 (3) Å, b=8.176 (5) Å, c=14.32 (2) Å, α=97.07° (7), β=96.75° (8), γ=103.73° (6), and z=2. The crystal structure of this compound has been determined using 3120 unique single crystal data. The final refinements let the agreement factors R₁ and wR₂(F²) converge to 0.0138 and 0.0363, respectively. [Ce(Suc)] is built up from infinite chains of edge-sharing nine-fold coordinated cerium atoms running along [100]. These chains are interconnected by the carbon atoms of the succinate anions, leading to a three-dimensional hybrid framework. The cell constants of [Sm(Suc)], isotypic with monoclinic C2/c [Pr(H₂O)]₂[O₂C(CH₂)₂CO₂]₃·H₂O ([Pr(Suc)]), were refined starting from X-ray powder data: a=20.275 (3) Å, b=7.919 (6) Å, c=14.130 (3) Å, and β=121.45° (1). Despite its lower symmetry, [Ce(Suc)] presents an important structural filiation with [Sm(Suc)]     

Syntheses, structures, and vibrational spectroscopy of the two-dimensional iodates Ln(IO3)3 and Ln(IO3)3(H2O) (LnYb, Lu)

The reaction of Lu³⁺ or Yb³⁺ and H₅IO₆ in aqueous media at 180 °C leads to the formation of Yb(IO₃)₃(H₂O) or Lu(IO₃)₃(H₂O), respectively, while the reaction of Yb metal with H₅IO₆ under similar reaction conditions gives rise to the anhydrous iodate, Yb(IO₃)₃. Under supercritical conditions Lu³⁺ reacts with HIO₃ and KIO₄ to yield the isostructural Lu(IO₃)₃. The structures have been determined by single-crystal X-ray diffraction. Crystallographic data are (MoKα, λ=0.71073 Å): Yb(IO₃)₃, monoclinic, space group P2₁/n, a=8.6664(9) Å, b=5.9904(6) Å, c=14.8826(15) Å, β=96.931(2)°, V=766.99(13), Z=4, R(F)=4.23% for 114 parameters with 1880 reflections with I>2σ(I); Lu(IO₃)₃, monoclinic, space group P2₁/n, a=8.6410(9), b=5.9961(6), c=14.8782(16) Å, β=97.028(2)°, V=765.08(14), Z=4, R(F)=2.65% for 119 parameters with 1756 reflections with I>2σ(I); Yb(IO₃)₃(H₂O), monoclinic, space group C2/c, a=27.2476(15), b=5.6296(3), c=12.0157(7) Å, β=98.636(1)°, V=1822.2(2), Z=8, R(F)=1.51% for 128 parameters with 2250 reflections with I>2σ(I); Lu(IO₃)₃(H₂O), monoclinic, space group C2/c, a=27.258(4), b=5.6251(7), c=12.0006(16) Å, β=98.704(2)°, V=1818.8(4), Z=8, R(F)=1.98% for 128 parameters with 2242 reflections with I>2σ(I). The f elements in all of the compounds are found in seven-coordinate environments and bridged with monodentate, bidentate, or tridentate iodate anions. Both Lu(IO₃)₃(H₂O) and Yb(IO₃)₃(H₂O) display distinctively different vibrational profiles from their respective anhydrous analogs. Hence, the Raman profile can be used as a complementary diagnostic tool to discern the different structural motifs of the compounds.     

Novel ammonium hexafluoroarsenate salts from reaction of (CF3)2NH,CF3N(OCF3)H,CF3N[OCF(CF3)2]H,CF3NHF and SF5NHF with the strong acid HF/ASF5.

Reactions of the fluorinated amines (CF₃)₂NH, CF₃N(OCF₃)H, CF₃N[OCF(CF₃)₂]H, CF₃NHF and SF₅NHF with the strong acid HF/AsF₅ form the corresponding ammonium salts R_f¹R_f²NH₂⁺AsF₆^? and R_fNFH₂⁺ AsF₆^? in high yield. [R_f¹=CF₃, R_f²=CF₃, CF₃O, (CF₃)₂CFO; R_f=CF₃, SF₅] The colorless crystalline solids are stable for prolonged periods at 22°C in sealed FEP containers. They have dissociation pressures at 22°C ranging from ～5 torr (R_fNFH₂⁺ AsF₆^?) to ～50 torr [CF₃N(OCF₃)H₂⁺AsF₆^?]. ¹⁹F NMR and Raman spectroscopy were used to identify the compounds.     

New ionic liquids with the bis[bis(pentafluoroethyl)phosphinyl]imide anion, [(C2F5)2P(O)]2N—Synthesis and characterization

A new series of low melting and hydrophobic ionic liquids (ILs) containing the bis[bis(pentafluoroethyl)phosphinyl]imide anion, [(C₂F₅)₂P(O)]₂N⁻ (FPI), and ammonium, phosphonium, imidazolium, pyridinium or pyrrolidinium cations were prepared and characterized. Their density, viscosity, melting point, glass transition temperature, decomposition temperature and conductivity are discussed. Many of these ionic liquids are liquids at room temperature with melting points below 15 °C, viscosities below 110 mm² s⁻¹ and thermal stabilities above 300 °C.