Complexation of Alkali Triflates by Crown Ethers: Synthesis and Crystal Structure of [Na(12‐crown‐4)2][SO3CF3], [Na(15‐crown‐5)][SO3CF3], [Rb(18‐crown‐6)][SO3CF3], and [Cs(18‐crown‐6)][SO3CF3]

Complexes of trifluoromethanesulfonates (triflates) with alkali metals Na, Rb, Cs have been prepared in the presence of various macrocyclic polyether crowns [(12‐crown‐4), (15‐crown‐5) and (18‐crown‐6)]. Depending on the combination of alkali ion with crown, the complexes include separated ion pairs [Na(12‐crown‐4)₂] [SO₃CF₃] ( 1 ) and contact ion pairs [Na(15‐crown‐5)] [SO₃CF₃] ( 2 ), [Rb(18‐crown‐6)] [SO₃CF₃] ( 3 ), and [Cs(18‐crown‐6)] [SO₃CF₃] ( 4 ), in which the triflate acts as a bidentate ligand. It is shown that the choice of crown ether is of paramount importance in determining the solid‐state structural outcome. The complex resulting from the pairing of crown ether ( 1 ) develops, when the crown ether is too small in relation to the alkali ion radius. When the cavity size of the crown ether is matched with the alkali ion radius, simple monomeric structures are identified in 2 , 3 and 4 . The title compounds crystallize in the monoclinic crystal system: 1 : space group P2/c with a = 9.942(3), b = 11.014(2), c = 10.801(3) Å, β = 97.30(2)°, V = 1173.1(4) ų, Z = 2, R1 = 0.0812, wR2 = 0.1133: 2 : space group P2₁/m with a = 7.949(2), b = 12.063(3), c = 9.094(2) Å, β = 105.98(2)°, V = 838.3(4) ų, Z = 2, R1 = 0.0869, wR2 = 0.1035: 3 : space group P2₁/c with a = 12.847(5), b = 8.448(2), c = 22.272(6) Å, β = 122.90(3)°, V = 2029.5(1) ų, Z = 4, R1 = 0.0684, wR2 = 0.1044: 4 : space group P2₁/n with a = 12.871(3), b = 8.359(1), c = 19.019(4) Å, β = 92.61(2)°, V = 2044.2(6) ų, Z = 4, R1 = 0.0621, wR2 = 0.0979.     

[Te8]2[Ta4O4Cl16]: A Two‐dimensional Tellurium Polycation obtained via Ionic Liquid‐Based Synthesis

By reaction of elemental tellurium, tellurium(IV) chloride, tantalum(V) chloride and tantalum(V) oxychloride in the ionic liquid [BMIM]Cl ([BMIM]Cl:1‐Butyl‐3‐methylimidazolium chloride),[Te₈]₂[Ta₄O₄Cl₁₆] is obtained in the form of lucent black crystals. The title compound consists of infinite [Te–Te–(Te₆)]_n²⁺ chains (Te–Te: 264.9(1)–284.3(1) pm) and isolated [Ta₄O₄Cl₁₆]^4– anions. The [Te–Te–(Te₆)]_n²⁺ chains are interconnected to form a two‐dimensional tellurium network (Te–Te: 335.9 pm). Due to this interaction the [Te–Te–(Te₆)]_n²⁺ chains in [Te₈]₂[Ta₄O₄Cl₁₆] show an arrangement that differs significantly from known polycationic [Te₈]_n²⁺ chains. The two‐dimensional tellurium network is finally separated by tetrameric, corner‐sharing oxidochloridotantalate anions [(TaO_2/2Cl_4/1)₄]^4– that are firstly observed. The composition of [Te₈]₂[Ta₄O₄Cl₁₆] is confirmed by EDX analysis; its optical band gap is estimated to 1.1–1.2 eV via UV/Vis spectroscopy.     

Synthesis,Structural Characterization and Physical Properties of a New Member of Ternary Lithium Layered Compounds – Li2RhO3

Li₂RhO₃ was synthesized by solid state reaction and its crystal structure was refined from X‐ray powder data by the Rietveld‐method. The compound was obtained as a black powder and crystallizes in the monoclinic space group C2/m, with unit cell parameters a = 5.1198(1), b = 8.8497(1), c = 5.1030(1) Å, β = 109.61(2) °, V = 217.80(1), and Z = 4. The structure determination shows that the oxygen atoms in Li₂RhO₃ form an approximate cubic close packing, where all octahedral voids are occupied by Rh⁴⁺ and Li⁺ cations. The structure is closely related to the α‐NaFeO₂ and Li₂MnO₃ layered structure types (layered variants of the NaCl‐type), but in Li₂RhO₃ the lithium and rhodium atoms are partially disordered. Li₂RhO₃ behaves as a semiconductor with rather small activation energy of 7.68 kJ · mol^–1 and is thermally stable up to 1273 K in argon atmosphere. According to measurements of the magnetic susceptibility in the temperature range from 2 to 330 K, Li₂RhO₃ is paramagnetic, obeys the Curie–Weiss law at temperatures above 150 K, and has an effective magnetic moment of 1.97 μ_B at 300 K.     

[(Te2)3{Mn(CO)3}2{Mn(CO)4}3]– – A Novel Tellurium‐­Manganese Carbonyl with Ufosane‐like Structure

By reacting Mn₂(CO)₁₀ and TeI₄ in the ionic liquid[BMIm][OTf] (1‐butyl‐3‐methylimidazolium trifluromethanesulfonate), brick‐red crystals of [BMIm][(Te₂)₃{Mn(CO)₃}₂{Mn(CO)₄}₃]are obtained. The title compound contains the carbonyl anion[(Te₂)₃{Mn(CO)₃}₂{Mn(CO)₄}₃]^–. Herein, three formal Te₂^2– units and two formal Mn(CO)₃⁺ fragments establish a distorted heterocubane‐like Te₆Mn₂ structure. Three edges of this heterocubane are furthermore capped by Mn(CO)₄⁺ fragments. The resulting Te₆Mn₅ building unit, moreover, looks very similar to the P₁₁^3– anion – the so‐called ufosane. The mean distances Te–Te and Te–Mn are observed with 277.6 and 264.7 pm, respectively. In addition to single‐crystal structure analysis, the title compound is characterized by infrared spectroscopy (FT‐IR), thermogravimetry (TG) and energy‐dispersive X‐ray (EDX) analysis.     

Ionic‐Liquid‐Based Synthesis of the Bromine‐Rich Bromidoplatinates [NBu3Me]2[Pt2Br10](Br2)2 and [NBu3Me]2[Pt2Br10](Br2)3

The bromine‐rich bromidoplatinates(IV) [NBu₃Me]₂[Pt₂Br₁₀](Br₂)₂ ( 1 ) and [NBu₃Me]₂[Pt₂Br₁₀](Br₂)₃ ( 2 ) were prepared by reaction of PtBr₄ and elemental bromine in the ionic liquid [MeBu₃N][N(Tf)₂] [N(Tf)₂ = bis(trifluoromethylsulfonyl)amide]. Both bromine‐rich bromidoplatinates(IV) contain [Pt₂Br₁₀]^2– anions and [NBu₃Me]⁺ cations as voluminous building units with an almost identical structural arrangement and very similar unit cells. The difference of the title compounds is related to the specific number of Br₂ molecules that link the [Pt₂Br₁₀]^2– anions to three‐dimensional networks. Whereas 1 is relatively stable under inert conditions, 2 releases bromine even at ambient pressure. The title compounds are characterized by single‐crystal structure analysis and Raman spectroscopy.     

Eight‐ and Twelve‐membered Cyclosilazoxanes: Structural Investigation of Two N‐Pentafluorophenyl‐substituted Si4N3O and Si6N2O4 Rings

The molecular structures of two N‐pentafluorophenylcyclosilazoxanes have been investigated. X‐Ray crystal structure determinations of (C₆F₅)₃Me₈Si₄N₃O ( 2 ) and (C₆F₅)₂Me₁₂Si₆N₂O₄ ( 3 ) revealed the first structurally authenticated examples of eight‐membered Si₄N₃O and twelve‐membered Si₆N₂O₄ ring systems.     

Structural Investigations and Thermal Behavior of (EMIm)[Cr(C2O4)2]·2H2O [1‐Ethyl‐3‐methylimidazolium Chromium(III) Dioxalate Dihydrate]

The crystal structure of EMIm diaquobis(μ‐oxalato)chromate(III) (1‐ethyl‐3‐methylimidazolium chromium(III) dioxalate dihydrate) was determined from X‐ray single crystal diffraction studies. A pale violet crystal of good optical quality was used for the structure determination at –100(2) and 25(2) °C. The basic crystallographic data for the low temperature structure are as follows: triclinic symmetry, space group P$\bar{1}$ , a = 7.6202(8) Å, b = 9.7668(9) Å, c = 10.7171(11) Å, α = 109.257(9)°, β = 90.494(8)°, γ = 105.685(8)°, V = 720.75(1) Å³. The crystal structure was solved by direct methods and refined (using anisotropic displacement parameters for all non‐hydrogen atoms) to a final residual of R₁ = 0.039 for 2062 independent observed reflections [I > 2σ(I)]. The compound is built up from alternating layers parallel to (010) containing (EMIm)⁺ cations or Cr(C₂O₄)₂(H₂O)₂^– anions, respectively. The two crystallographically independent Cr(C₂O₄)₂(H₂O)₂ octahedra reside on centers of symmetry (Wyckoff sites 1a and 1f). The corners of the octahedra consist of four oxygen atoms from two oxalate groups and two additional water molecules. EMIm⁺ cations provide linkage between different octahedral layers by hydrogen bridging. The water molecules in turn form hydrogen bonds with adjacent octahedra within the same layer. According to DTA/TG experiments the present compound shows several thermal processes in the range between room temperature and 1000 °C. However, pyrolysis is reproducibly yielding pure inorganic composites, qualifying this novel organic‐inorganic hybrid salt also as a stable precursor for nanoscalar ceramic materials. The final product consists of a distinct mixture of Cr₂O₃ and Cr₃C₂ in the molar ratio of 1:1. Concomittant oxide and carbide formation is an unprecedented disintegration pathway of the thermal treatment of oxalatochromates without reducing atmosphere.     

Physical Properties of 8‐Substituted 5,7‐Dichloro‐2‐Styrylquinolines as Potential Light Emitting Materials

Derivatives of 5,7‐dichloro‐2‐styrylquinoline ( 1 ), modified at position 8 of quinoline moiety with a methyl ether ( 4 , DCSQM) or acetate ( 5 , DCSQA), were synthesized and investigated. Both compounds exhibited high thermal stability (Td > 320 °C). The UV‐vis absorption of DCSQM and DCSQA varied only slightly in different solvents, whereas the emission spectra showed pronounced red shifts with increasing solvent polarity, suggesting the intramolecular charge transfer character of the emission state. Compounds 4 and 5 can emit lights from blue to green color in different solvents. The solvent polarity dependent electronic transitions are attributed to efficient intramolecular charge transfer (ICT) processes, in which the HOMOs and LUMOs are localized on the styrene‐based ring and the quinoline‐based moiety, respectively. The quinoline‐based LUMO provides compelling evidence that the first reduction site occurs on the electron‐deficient quinoline moiety.     

The First Homoleptic Bis(trifluoromethanesulfonyl)amide Complex of Yttrium: [bmim][Y(Tf2N)4]

1‐Butyl‐3‐methylimidazolium tetrakis‐(bis(trifluoromethanesulfonyl)amide)yttrium(III), [bmim][Y(Tf₂N)₄], was obtained from the ionic liquid 1‐butyl‐3‐methylimidazoliumbis(trifluoromethanesulfonyl)amide, [bmim][Tf₂N] and yttrium(III)bis(trifluoromethanesulfonyl)amide, Y(Tf₂N)₃. The crystal structure [monoclinic, C2/c (no. 15), a = 2096.(1), b = 1451.5(1), c = 1608.55(9) pm, β = 109.669(6)°, V = 4608.1(5)·10⁶ pm³, Z = 4, R₁ for 3874 symmetry independent reflections with I₀>2σ(I₀): 0.0438] contains Y^III coordinated by four Tf₂N‐ligands which all adopt a transoid‐conformation with respect to their –CF₃ groups. The oxygen coordination polyhedron around Y^III can be best described as a trigonal dodecahedron.One 1‐butyl‐3‐methylimidazolium cation compensates for the charge of the complex [Y(Tf₂N)₄]^? anion.     

Ionic‐liquid‐based ultrasound/microwave‐assisted extraction of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one from maize (Zea mays L.) seedlings

We evaluated an ionic‐liquid‐based ultrasound/microwave‐assisted extraction method for the extraction of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one from etiolated maize seedlings. We performed single‐factor and central composite rotatable design experiments to optimize the most important parameters influencing this technique. The best results were obtained using 1.00 M 1‐octyl‐3‐methylimidazolium bromide as the extraction solvent, a 50°C extraction temperature, a 20:1 liquid/solid ratio (mL/g), a 21 min treatment time, 590 W microwave power, and 50 W fixed ultrasonic power. We performed a comparison between ionic‐liquid‐based ultrasound/microwave‐assisted extraction and conventional homogenized extraction. Extraction yields of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one by the ionic‐liquid‐based ultrasound/microwave‐assisted extraction method were 1.392 ± 0.051 and 0.205 ± 0.008 mg/g, respectively, which were correspondingly 1.46‐ and 1.32‐fold higher than those obtained by conventional homogenized extraction. All the results show that the ionic‐liquid‐based ultrasound/microwave‐assisted extraction method is therefore an efficient and credible method for the extraction of 2,4‐dihydroxy‐7‐methoxy‐1,4‐benzoxazin‐3‐one and 6‐methoxy‐benzoxazolin‐2‐one from maize seedlings.     

Reaction with SO3 in Ionic Liquids: The Example of K2(S2O7)­(H2SO4)

The ionic liquid 1‐butyl‐3‐methylimidazolium hydrogensulfate, [bmim]HSO₄, turned out to be resistant even to strong oxidizers like SO₃. Thus, it should be a suitable solvent for the preparation of polysulfates at low temperatures. As a proof of principle we here present the synthesis and crystal structure of K₂(S₂O₇)(H₂SO₄), which has been obtained from the reaction of K₂SO₄ and SO₃ in [bmim]HSO₄. In the crystal structure of K₂(S₂O₇)(H₂SO₄) (orthorhombic, Pbca, Z = 8, a = 810.64(2) pm, b = 1047.90(2) pm, c = 2328.86(6) pm, V = 1978.30(8) ų) two crystallographically unique potassium cations are coordinated by a different number of monodentate and bidentate‐chelating disulfate anions as well as by sulfuric acid molecules. The crystal structure consists of alternating layers of [K₂(S₂O₇)] slabs and H₂SO₄ molecules. Hydrogen bonds between hydrogen atoms of sulfuric acid molecules and oxygen atoms of the neighboring disulfate anions are observed.     

Aggregation of phosphate and 1‐tetradecyl‐3‐methylimidazolium chloride background electrolytes during micellar electrokinetic chromatography

We report the possible aggregation of phosphate and ionic liquid (1‐tetradecyl‐3‐methylimidazolium chloride) based BGEs during MEKC. After a certain transit period, the aggregates appear as a random sequence of spikes on a UV detector signal. Root mean square values of the spikes and aggregation time (T_a) were plotted against BGE concentrations. The observation suggests that MEKC is a simple and easy technique for micelle aggregation studies.     

α‐RbO3, a Low Temperature Polymorph of Rubidium Ozonide

Applying the known procedure for synthesis of alkali metal ozonides, just at a lower temperature, has yielded a new polymorph of rubidium ozonide, α‐RbO₃ [P2₁; a = 436.3(2), b = 595.3(3), c = 548.7(3) pm, β = 99.680(7), R = 0.0400, 1184 reflections]. Like previously reported β‐RbO₃, the basic structural arrangement of anions and cations corresponds to the CsCl type of structure, however, the mutual orientation of the ozonide ions is different, in as much as one of the two terminal oxygen atoms is pointing to the adjacent bridging oxygen atom, forming a chain running along the b axis.     

Luminescent Soft Material: Two New Europium‐Based Ionic Liquids

Two new Eu‐based ionic liquid systems, [C₄mim][DTSA] : [Eu(DTSA)₃] and 2[C₄mim] [DTSA] : [Eu(DTSA)₃] were synthesized at 120° under inert conditions from 1‐butyl‐1‐methylimidazolium ditoluenesulfonylamide ([C₄mim][DTSA]). The identity and purity of the synthesized compounds were confirmed by elemental analysis, IR, Raman, and ¹H‐NMR spectroscopy. As they solidify below 100° as glasses they qualify as ionic liquids. Fluorescence measurements show that the materials exhibit a strong red luminescence of high color purity. Therefore, they have the potential to be used for optical applications such as in emission displays.     

Preparation of chiral oxazolinyl‐functionalized β‐cyclodextrin‐bonded stationary phases and their enantioseparation performance in high‐performance liquid chromatography

A simple procedure for the synthesis of three new oxazolinyl‐substituted β‐cyclodextrins (6‐deoxy‐6‐R‐(–)‐4‐phenyl‐4,5‐dihydrooxazolinyl‐β‐cyclodextrin, 6‐deoxy‐6‐S‐(–)‐4‐phenyl‐4,5‐dihydrooxazolinyl‐β‐cyclodextrin, and 6‐deoxy‐6‐S‐(–)‐(4‐pyridin‐1‐ium‐4‐methyl‐benzenesulphonate)‐4,5‐dihy‐drooxazolinyl‐β‐cyclodextrin) and their covalent bonding to silica are reported. The ability of these chiral stationary phase columns for separating compounds is also presented and discussed. Twenty‐eight compounds were examined in the polar‐organic mobile phase mode, and 11 β‐nitroethanols were tested in the reversed‐phase mode. Excellent enantioseparations were achieved for most of the analytes, even for several challenging compounds. The rigid and flexible structures of mono‐substituted chiral groups and the fragments around the rim of the β‐cyclodextrin cavity played an important role in the separation process. Factors such as π–π stacking, dipole–dipole interactions, ion‐pairing, and steric hindrance effects were found to affect the chromatographic performance. Moreover, the buffer composition, and percentages of organic modifiers in the mobile phase, were investigated and compared. The mechanisms involved in the separation were postulated based on the chromatographic data.     

Reversible Carbene Formation in the Ionic Liquid 1‐Ethyl‐3‐Methylimidazolium Acetate by Vaporization and Condensation

The role of N‐heterocyclic carbenes in the chemistry of ionic liquids based on imidazolium salts has long been discussed. Here, we present experimental evidence that 1‐ethyl‐3‐methylimidazolium‐2‐ylidene (EMIm) can coexist with its protonated imidazolium cation (EMImH⁺) at low temperatures. If the vapor of the ionic liquid [EMImH⁺][AcO^?] is trapped in solid argon or nitrogen at 9 K, only acetic acid (AcOH) and the carbene, but no ionic species, are found by IR spectroscopy. This indicates that during the evaporation of [EMImH⁺][AcO^?] proton transfer occurs to form the neutral species. If the vapor of [EMImH⁺][AcO^?] is trapped at 9 K as film in the absence of a host matrix, a solid consisting of EMImH⁺, EMIm, AcO^?, and AcOH is formed. During warming to room temperature the proton transfer in the solid to form back the IL [EMImH⁺][AcO^?] can be monitored by IR spectroscopy. This clearly demonstrates that evaporation and condensation of the IL [EMImH⁺][AcO^?] results in a double proton transfer, and the carbene EMIm is only metastable even at low temperatures.     

Natriumtrithiophosphat(V): Kristallstruktur und Natriumionenleitfähigkeit

Sodium Trithiophosphate(V): Crystal Structure and Sodium Ionic Conductivity Na₃POS₃ was synthesized from the corresponding hydrate by freeze‐drying. The crystal structure of Na₃POS₃ was determined using X‐ray and neutron powder data, and refined applying simultaneous Rietveld refinements of the neutron and X‐ray data (Cmc2₁, a = 9.5105(1), b = 11.5463(1), c = 5.9323(1)Å, R_p = 5.37 %, R_wp = 4.47 %). The barycenters of the POS₃ tetrahedra are arranged in the sense of a hexagonal close packing. The P—O bonds are oriented in a polar manner parallel to the c‐axis, and with the PS₃‐groups in an eclipsed mutual orientation. The structure of Na₃POS₃ is closely related (maximal subgroup) to the one of Ca₃CrN₃. Above 250 °C, Na₃POS₃ can be considered as a fast ionic conductor due to its throughout high conductivity.     

Calculation of Some Thermodynamic Properties and Detonation Parameters of 1‐Ethyl‐3‐Methyl‐H‐Imidazolium Perchlorate, [Emim][ClO4], on the Basis of CBS‐4M and CHEETAH Computations Supplemented by VBT Estimates

This paper estimates some thermochemical (in kcal mol^–1) and detonation parameters for the ionic liquid, [emim][ClO₄] and its associated solid in view of its investigation as an energetic material. The thermochemical values estimated, employing CBS‐4M computational methodology and volume‐based thermodynamics (VBT) include: lattice energy, U_POT([emim][ClO₄]) ≈? 123 ± 16 kcal · mol^–1; enthalpy of formation of the gaseous cation, Δ_fH°([emim]⁺, g) = 144.2 kcal · mol^–1 and anion, Δ_fH°([ClO₄]^–, g) = –66.1 kcal · mol^–1; the enthalpy of formation of the solid salt, Δ_fH°([emim][ClO₄],s) ≈? –55 ± 16 kcal · mol^–1 and for the associated ionic liquid, Δ_fH^o([emim][ClO₄],l) = –52 ± 16 kcal · mol^–1 as well as the corresponding Gibbs energy terms: Δ_fG°([emim][ClO₄],s) ≈? +29 ± 16 kcal · mol^–1 and Δ_fG^o([emim][ClO₄],l) = +24 ± 16 kcal · mol^–1 and the associated standard absolute entropies, of the solid [emim][ClO₄], S°₂₉₈([emim][ClO₄],s) = 83 ± 4 cal · K^–1 · mol^–1. The following combustion and detonation parameters are assigned to [emim][ClO₄] in its (ionic) liquid form: specific impulse (I_sp) = 228 s (monopropellant), detonation velocity (V_oD) = 5466 m · s^–1, detonation pressure (p_C–J) = 99 kbar, explosion temperature (T_ex) = 2842 K.