Bis{2-[(2-hydroxyethyl)iminomethyl]phenolato}gold(III) tetrachloroaurate(III)

The title compound, [Au-III(C9H10NO2)(2)][(AuCl4)-Cl-III], contains [Au-III(C9H10NO2)(2)](+) cations and [(AuCl4)-Cl-III](-) anions with each of the gold(III) ions in a typical four-coordinate square-planar geometry. Both gold(III) metal centers are located on inversion centers.

Bis(tetrabutylammonium) decaiodotetramercurate(II), (Bu4N)(2)[Hg4I10]

Bu4N)(2)[Hg4I10] is the first compound for which tetranuclear anions [Hg4I10](2-) are observed in its crystal structure. Charge balance is achieved by ordered [Bu4N](+) cations.

Speciation of Chlorometallate Ionic Liquids Based on Gallium(III) and Indium(III)

A range of ionic liquids was prepared by mixing 1-alkyl-3-methylimidazolium chloride with gallium(III) chloride or indium(III) chloride in various ratios, producing both acidic and basic compositions. Their speciation was investigated using Ga-71 NMR or In-115 NMR spectroscopy, as well as extended X-ray absorption fine structure. Polynuclear Lewis acidic anions, [MxCl3x+1](-), were found in chlorogallate(III) ionic liquids, but not in chloroindate(III) systems.

Synthesis, Structure, and Spectroscopic Properties of the New Lanthanum(III) Fluoride Oxomolybdate(VI) La3FMo4O16

La3FMo4O16 crystallizes in the triclinic crystal system with space group P (1) over bar [a = 724.86(2) pm, b = 742.26(2) pm, c = 1469.59(3) pm, a = 101.683(2)degrees, beta 102.118(2)degrees, gamma = 100.279(2)degrees] with two formula units per unit cell. The three crystallographically independent La3+ cations show a coordination number of nine each, with one F- and eight O2- anions forming distorted monocapped square antiprisms. The fluoride anion is coordinated by all three lanthanum cations to form a nearly planar triangle. Besides three crystallographically independent tetrahedral [MoO4](2-) units, a fourth one with a higher coordination number (CN = 4 +1) can be found in the crystal structure, forming a dimeric entity with a formula of [Mo2O8](4-) consisting of two edge-connected square pyramids. Several spectroscopic measurements were performed on the title compound, such as infrared, Raman, and diffuse reflectance spectroscopy. Furthermore, La3FMo4O16 was investigated for its capacity to work as host material for doping with luminescent active cations, such as Ce3+ or Pr3+. Therefore, luminescence spectroscopic as well as EPR measurements were performed with doped samples of the title compound. Both the pure and the doped compounds can be synthesized by fusing La2O3, LaF3 and MoO3 (ratio 4:1:12; ca. 1 % CeF3 and PrF3 as dopant, respectively) in evacuated silica ampoules at 850 degrees C for 7 d.

Ionic liquid S-alkylthiouronium salts

The prepn. and characterization of a series of ionic liqs. based on S-alkylthiouronium cations prepd. from thiourea, 1,3-dimethylthiourea, 1,3-diethylthiourea and 1,3-tetramethylthiourea coupled with bis{(trifluoromethane)sulfonyl}imide, bromide, methylsulfate or ethylsulfate anions are reported. All are liqs. at room temp. or solids with m.ps. close to room temp., except for the bromide salts, which have m.ps. below 92 °C. Systematic variation in the N- and S-alkyl substituents demonstrates how the phys. properties of these ionic liqs. can be readily controlled. The mutual miscibility limits of representative examples with octane, dodecane and toluene have been detd. as a function of temp., and the extn. of dibenzothiophene from dodecane as a model for desulfurisation of diesel has been investigated.

Thermophysical Properties of Amino Acid-Based Ionic Liquids

Ionic liquids (ILs) having either cations or anions derived from naturally occurring amino acids have been synthesized and characterized as amino acid-based ionic liquids (AAILs) In this work, the experimental measurements of the temperature dependence or density. viscosity, heat capacity, and thermal conductivity of several AAILs, namely, tributylmethylammonium serinate ([N-444][Ser], tributylmethylammonium taurmate ([N-444][Tau]) tributylmethylammonium lysinate a [N-444][ Lys]), tributylmethylammonium threonate ([N-444][Thr]), tetrabutylphosphonium serinate ([P-4444][Ser]), tetrabutylphosphonium taurmate ([P-4444][Tau]), tetrabutylphosphonium lysinate ([P-4444][Lys]), tetrabutylphosphonium threonate P-4444 Thr tetrabutylphosphonium prolinate P-4444 ((Pro(), tetrabutylphosphonium valinate ([P-4444][Val]), and tetrabutylphosphonium cysteinate ([P-4444][Cys]), are presented The influence of cations and anions on studied properties is discussed. On the basis of experimental data. the QSPR (quantitative structure property relationship) correlations and group contribution methods for thermophysical properties of AAILs have been developed, which form the basis for the development of the computer-aided molecular design (CAMD) of AAILs It has also been demonstrated that that the predictive data obtained by con elation methods ale in good agreement with the experimental data The correlations developed, herein. can thus be used to evaluate the studied thermophysical properties of AAILs for use in process design or in the CAMD of new AAILs

Solid and liquid charge-transfer complex formation between 1-methylnaphthalene and 1-alkyl-cyanopyridinium bis{(trifluoromethyl)sulfonyl}imide ionic liquids

Liquid charge-transfer (CT) complexes were observed to form on contacting electron-rich aromatics with electron withdrawing group appended 1-alkyl-4-cyanopyridinium ionic liquids (ILs). Cooling below the melting point of the ionic liquid resulted in crystallisation of ionic liquid from the complex for 2-cyano and 3-cyano pyridinium isomers and in the formation of a 1 : 1 IL : aromatic crystalline CT-complex with the 4-cyanopyridinium isomer. The liquid structure of a 1 : 1 mixture of 1-methyl-4-cyanopyridinium bis{(trifluoromethyl)sulfonyl} imide with 1-methylnaphthalene has been probed by neutron diffraction experiments and molecular dynamics simulations. A high degree of correlation between the experimental data and the simulations was found with a significant displacement of the anions from around the cation by the aromatic species and the resulting structure having pi-pi stacks between the cations and the aromatic.

Chromo- and fluorogenic Organometallic Sensors

Compounds that change their absorption and/or emission properties in the presence of a target ion or molecule have been studied for many years as the basis for optical sensing. Within this group of compounds, a variety of organometallic complexes have been proposed for the detection of a wide range of analytes such as cations (including H+), anions, gases (e.g. O2, SO2, organic vapours), small organic molecules, and large biomolecules (e.g. proteins, DNA). This chapter focuses on work reported within the last few years in the area of organometallic sensors. Some of the most extensively studied systems incorporate metal moieties with intense long-lived metal-to-ligand charge transfer (MLCT) excited states as the reporter or indicator unit, such as fac-tricarbonyl Re(I) complexes, cyclometallated Ir(III) species, and diimine Ru(II) or Os(II) derivatives. Other commonly used organometallic sensors are based on Pt-alkynyls and ferrocene fragments. To these reporters, an appropriate recognition or analyte-binding unit is usually attached so that a detectable modification on the colour and/or the emission of the complex occurs upon binding of the analyte. Examples of recognition sites include macrocycles for the binding of cations, H-bonding units selective to specific anions, and DNA intercalating fragments. A different approach is used for the detection of some gases or vapours, where the sensor's response is associated with changes in the crystal packing of the complex on absorption of the gas, or to direct coordination of the analyte to the metal centre.

Kinetic and thermodynamic investigations on arsenic adsorption onto dolomitic sorbents

Arsenic and its compounds are toxic pollutants for the environment and all living organisms. At present, there is considerable interest in studying new sorbent materials for the removal of arsenic from aqueous solutions. This work discusses the feasibility of arsenic uptake onto dolomite which is considered to be a potential inexpensive adsorbent. Thermodynamic and kinetic experiments were undertaken to assess the capacity and rate of As uptake onto dolomite. Experimental data were mathematically described using adsorption kinetic models, namely pseudo-first-order and pseudo-second-order models. The arsenic removal was found to be dependent on the dosage of dolomite, adsorbent particle size and the presence of various anions. Thermodynamic results indicate that the adsorption follows an exothermic chemisorption process. The experimental data indicate successful removal of As(V) ion from aqueous solution indicating that dolomite be used as an inexpensive treatment process. (C) 2010 Elsevier B.V. All rights reserved.

Electron attachment to 2-nitro-m-xylene

Electron attachment to nitroaromatic compound 2-nitro-m-xylene in gas phase has been performed utilizing a double focusing two sector mass spectrometer with high mass resolution (m/Delta m approximate to 2500). At low energy (below 20 eV), electron interactions with the neutral 2-nitro-m-xylene molecule reveal a very rich fragmentation pattern. A total of 60 fragment anions have been detected and the ion yield for all observed negative ions has been recorded as a function of the incident electron energy, among them a long lived (metastable) non-dissociated parent anion which is formed at energies near zero eV, and some ions observed at the mass numbers 26,42 and 121. Comparison of calculated isotopic patterns with measured ion yields for these fragment anions and their successors in the mass spectrum, allows the assignment of the chemical composition of these fragments as CN- (26 Da), CNO- (42 Da) and C8H9O- (121 Da). Electron attachment to 2-nitro-m-xylene leads to anion formation at four energy ranges. Between 0 eV and 2 eV only few product ions are formed. Between 4.6 eV and 6.1 eV all fragment anions are formed and for most of them the anion yield reaches its maximum value in this range. NO2- which is the most abundant product [M-H](-) and O- are the only fragments that exhibit a feature at 7.4eV, 8.1 eV and 7.9eV, respectively. About half of the fragment anions exhibit a broad, mostly low-intensity resonance between 9 eV and 10 eV. (C) 2009 Elsevier B.V. All rights reserved.

Low-Energy Electron Attachment to the Dichlorodifluoromethane (CCl2F2) Molecule

Results from a joint experimental study of electron attachment to dichlorodifluoromethane (CCl2F2) molecules in the gas phase are reported. In a high resolution electron beam experiment involving two versions of the laser photoelectron attachment method, the relative cross section for formation of the dominant anion Cl- wits measured over the energy range 0.001-1.8 eV at the gas temperature T-G = 300 K. It exhibits cusp structure at thresholds for vibrational excitation of the v(3)(a(1)) mode due to interaction with the attachment channels. With reference to the thermal attachment rate coefficient k(T-e;T-G = 300 K) = 2.2(8) x 10(-9) cm(-3) s(-1) (fitted average from several data), a new highly resolved absolute attachment cross section for TG = 300 K was determined. Partial cross sections for formation of the anions Cl-, Cl-2(-), F-, ClF-, and CCl2F- were measured over the range 0-12 eV, using three different electron beam experiments of medium energy resolution. The dependence of the attachment rate coefficient k(T-e;T-G = 300 K) on electron temperature T-e wits calculated over the range 50-15 000 K, based on a newly constructed total cross section for anion formation at T-G = 300 K. R-matrix Calculations for Cl- production have been carried out for comparison with the experimental data. The R-matrix results are in line with the main experimental observations and predict the dependence of the DEA cross section on the initial vibrational level v(3) and on the vibrational temperature. Furthermore, the cross section for I Vibrational excitation of the v(3) mode hits been computed.

Anion-templated formation of a unique inorganic 'super-adamantoid' cage [Ag-6(triphos)(4)(O3SCF3)(4)](2+) [triphos = (PPh2CH2)(3)CMe]

In the presence of templating anions, 2:3 molar mixtures of triphos and silver(I) cations unexpectedly give novel hexanuclear cages, which result from an unusual 'endo-methyl' geometry of the triphos ligands.

TRANSIENT RESONANCE RAMAN AND RAMAN SPECTROELECTROCHEMICAL STUDIES OF CUI COMPLEXES WITH POLYPYRIDYL LIGANDS

Studies by laser flash photolysis, transient Raman spectroscopy, and Raman and UV-vis spectroelectrochemistry are described in which the techniques have been used in parallel to compare the lowest energy charge-transfer excited states of Cu (1) complexes ([Cu(L)2]+ and [ (PPh3)2Cu(L)]+ [L = 2,2'-biquinoline (BIQ) or 6,7-dihydro-5,8-dimethyldibenzo[b,j] [1,10]-phenanthroline (DMCH)) with the species produced by electrochemical reduction in the same group of complexes. Transient resonance Raman spectra for the metal-to-ligand charge-transfer (MLCT) states of [Cu(DMCH)2]+ (1), [Cu(BIQ)2]+ (2), [Cu(DMCH)(PPh3)2]+ (3), and [Cu(BIQ)(PPh3)2]+ (4) are compared with the resonance Raman spectra of the same group of complexes following one-electron electrochemical reduction of the DMCH and BIQ ligands. The UV-vis and resonance Raman evidence suggests that the electrochemical reduction of the [Cu(I)L2]+ species proceeds according to the sequence [LCu(I)L]+ -->e- [LCu0L] -->e- [L.-Cu(I)L.-]-. Several features assignable to modes of the electrochemically generated DMCH.-and BIQ'- radical anions exhibit a close correspondence in both frequency and relative intensity with counterparts in the spectra of the MLCT states of 1 and 2. A notable exception is a band near 1590 cm-1 in the spectra of the electrochemically reduced species which occurs some 15 cm-1 lower in the corresponding spectra of the excited-state species. It is suggested that the shift may reflect the change in oxidation state of the metal center from Cu(I) to Cu(II) which occurs as a result of charge-transfer excitation.

Electrochemistry of Hg(II) Salts in Room-Temperature Ionic Liquids

The electrochemistry of HgCl(2) and [Hg(NTf(2))(2)] ([NTf(2)](-) = bis-{(trifluoromethyl)sulfonyl}imide) has been studied in room temperature ionic liquids. It has been found that the cyclic voltammetry of Hg(II) is strongly dependent on a number of factors (e.g., concentration, anions present in the mixture, and nature of the working electrode) and differs from that found in other media. Depending on conditions, the cyclic voltammetry of Hg(II) can give rise to one, two, or four reduction peaks, whereas the reverse oxidative scans show two to four peaks. Diffuse reflectance UV-vis spectroscopy and X-ray powder diffraction have been used to aid the assignment of the voltammetric waves.

Transport properties of protic ionic liquids, pure and in aqueous solutions: Effects of the anion and cation structure

Ionic conductivities of twelve protic ionic liquids (PILs) and their mixtures with water over the whole composition range are reported at 298.15 K and atmospheric pressure. The selected PILs are the pyrrolidinium-based PILs containing nitrate, acetate or formate anions; the formate-based PILs containing diisopropylethylammonium, amilaminium, quinolinium, lutidinium or collidinium cations; and the pyrrolidinium alkylcarboxylates, [Pyrr][CnH2n+1COO] with n = 5–8. This study was performed in order to investigate the influence of molecular structures of the ions on the ionic conductivities in aqueous solutions. The ionic conductivities of the aqueous solutions are 2–30 times higher than the conductivities of pure PILs. The maximum in conductivity varies from ww=0.41???to???0.74 and is related to the nature of cations and anions. The molar conductance and the molar conductance at infinite dilution for (PIL + water) solutions are then determined. Self-diffusion coefficients of the twelve protic ionic liquids in water at infinite dilution and at 298.15 K are calculated by using the Nernst–Haskell, the original and the modified Wilke–Chang equations. These calculations show that similar values are obtained using the modified Wilke–Chang and the Nernst–Haskell equations. Finally, the effective hydrodynamic (or Stokes) radius of the PILs was determined by using the Stokes–Einstein equation. A linear relationship was established in order to predict this radius as a function of the anion alkyl chain length in the case of the pyrrolidinium alkylcarboxylates PILs.