Triple Ions Research Articles

Ion association and solvation behavior of tetraalkylammonium iodides in binary mixtures of dichloromethane + N,N-dimethylformamide probed by a conductometric study

Precise measurements on electrical conductances of tetraalkylammonium iodides, R(4)NI (R = n-butyl to n-heptyl), in different mass% (0-100) of dichloromethane (DCM) + N,N-dimethylformamide (DMF) at 298.15 K have been performed. Limiting molar conductances (Λ(0)), association constants (K(A)) and co-sphere diameter (R) for ion-pair formation in the mixed solvent mixtures have been evaluated using the Fuoss conductance-concentration equation. However, the deviation of the conductometric curves (Λ versus √c) from linearity for the electrolytes in 100 mass% of DCM indicated triple ion formation, and therefore corresponding conductance data have been analyzed by the Fuoss-Kraus theory of triple ions. Limiting ionic molar conductances λ have been calculated by the reference electrolyte method along with a numerical evaluation of ion pair and triple ion formation constants (K(P)≈K(A) and K(T)). The results have been interpreted in terms of ion-solvent interactions and structural changes in the mixed solvents.

Phase behaviour and conductivity study on multi-component mixtures for electrodeposition in supercritical fluids

Electrochemistry in supercritical CO(2) (scCO(2)) is difficult because the very low dielectric constant of the fluid restricts the solubility of ionic species and the conductivity of dissolved electrolytes. To overcome this problem to allow us to carry out electrodeposition at macroelectrodes from scCO(2) we have investigated the use of co-solvents and modified electrolyte salts chosen to increase their solubility and dissociation in the supercritical fluid. Here we report results of phase behaviour studies for mixtures of CO(2) with [NBu(n)(4)][BF(4)] and either methanol (CH(3)OH) or acetonitrile (CH(3)CN) as the co-solvent. These show that the solubility of [NBu(n)(4)][BF(4)] is approximately 5 times larger when CH(3)CN is the co-solvent rather than CH(3)OH. Consequently the phase behaviour of the ternary of CO(2)-[NBu(n)(4)][BF(4)]-CH(3)CN was studied in greater detail over a range of compositions. To enhance the conductivity of scCO(2)-CH(3)CN a range of electrolyte salts was synthesised in which the [NBu(n)(4)](+) and/or [BF(4)](-) ion were replaced by different derivatives. Results for the phase behaviour and conductivity of these modified electrolyte salts in scCO(2)-CH(3)CN are reported for several different compositions. We find that increasing the degree of fluorination and size of the ions increases the solubility of the electrolyte salt in scCO(2)-CH(3)CN. Of the 11 electrolytes investigated [NBu(n)(4)][B{3,5-C(6)H(3)(CF(3))(2)}(4)] appears the most suitable for use in scCO(2)-CH(3)CN with a molar conductivity of 22-26 S cm(2) mol(-1) and a maximum measured conductivity of approximately 3 mS cm(-1) for 0.07 M [NBu(n)(4)][B{3,5-C(6)H(3)(CF(3))(2)}(4)] dissolved in scCO(2)-CH(3)CN (molar ratio CH(3)CN : CO(2) approximately 0.12) at 20 MPa and 328.15 K. This is an order of magnitude improvement over similar results for the [NBu(n)(4)][BF(4)] parent. Studies of the conductance as a function of the electrolyte concentration suggest that triple ions make an important contribution to the conductivity of the supercritical fluid.

Electron Capture Dissociation Mass Spectrometry of Metallo-Supramolecular Complexes

The electron capture dissociation (ECD) of metallo-supramolecular dinuclear triple-stranded helicate Fe(2)L(3)(4+) ions was determined by Fourier transform ion cyclotron resonance mass spectrometry. Initial electron capture by the di-iron(II) triple helicate ions produces dinuclear double-stranded complexes analogous to those seen in solution with the monocationic metal centers Cu(I) or Ag(I). The gas-phase fragmentation behavior [ECD, collision-induced dissociation (CID), and infrared multiphoton dissociation (IRMPD)] of the di-iron double-stranded complexes, (i.e., MS(3) of the ECD product) was compared with the ECD, CID, and IRMPD of the Cu(I) and Ag(I) complexes generated from solution. The results suggest that iron-bound dimers may be of the form Fe(I)(2)L(2)(2+) and that ECD by metallo-complexes allows access, in the gas phase, to oxidation states and coordination chemistry that cannot be accessed in solution.

A validated assay for the quantitative analysis of vatalanib in human EDTA plasma by liquid chromatography coupled with electrospray ionization tandem mass spectrometry

A sensitive and accurate method for the determination of vatalanib in human EDTA plasma was developed using high-performance liquid chromatography and detection with tandem mass spectrometry. Stable isotopically labeled imatinib was used as internal standard. Plasma proteins were precipitated and an aliquot of the supernatant was directly injected onto a Phenomenex Gemini C18 analytical column (50 mm × 2.0 mm ID, 5.0 μm particle size) and then compounds were eluted with a linear gradient. The outlet of the column was connected to a Sciex API 365 triple quadrupole mass spectrometer and ions were detected in positive multiple reaction monitoring mode. The lower limit of quantification was 10 ng/mL (S/N ≈ 10, CV ≤ 8.4%). This method was validated over a linear range from 10 to 2500 ng/mL, and results from the validation study demonstrated a good intra- and inter-assay accuracy (inaccuracy ≤9.57%) and precision (CV ≤ 8.81%). This method has been used to determine plasma vatalanib concentrations in patients with advanced solid tumor, enrolled in a phase I pharmacokinetic trial with the drug.

Solution Structures of Lithium Enolates of Cyclopentanone, Cyclohexanone, Acetophenones, and Benzyl Ketones. Triple Ions and Higher Lithiate Complexes

Multinuclear NMR spectroscopic studies at low temperature (-110 to -150 degrees C) revealed that lithium p-fluorophenolate and the lithium enolates of cyclohexanone, cyclopentanone and 4-fluoroacetophenone have tetrameric structures in THF/Et(2)O and THF/Et(2)O-HMPA by study of the effects of the addition of HMPA. The Z and E isomers of the lithium enolate of 1,3-bis-(4-fluorophenyl)-2-propanone (5F-Li) show divergent behavior. The Z isomer is completely dimeric in pure diethyl ether, and mostly dimeric in 3:2 THF/ether, where monomer could be detected in small amounts. TMTAN and PMDTA convert Z-5F-Li to a monomeric amine complex, and HMPA converts it partially to monomers, and partially to lithiate species (RO)(2)Li(-) and (RO)(3)Li(2-). Better characterized solutions of these lithiates were prepared by addition of phosphazenium enolates (using P4-(t)Bu base) to the lithium enolate in 1:1 ratio to form triple ion (RO)(2)Li(-) P4H(+), or 2:1 ratio to form the higher lithiate (RO)(3)Li(2-) (P4H(+))(2)) (quadruple ions). The E isomer of 5F-Li is also dimeric in 3:2 THF/Et(2)O solution, but is not detectably converted to monomer either by PMDTA or HMPA. In contrast to Z-5F-Li, the E isomer is tetrameric in diethyl ether even in the presence of excess HMPA. Thus for the two isomers of 5F six different enolate structures were characterized: tetramer, dimer, CIP-monomer, SIP-monomer, triple ion, and quadruple ion.

Ion Pair and Triple Ion Formation by Some Tetraalkylammonium Iodides in Binary Mixtures of Carbon Tetrachloride + Nitrobenzene

Electrical conductances of tetraalkylammonium iodides, R4NI (R = butyl to heptyl), in different mass % (20 to 80) of carbon tetrachloride (CCl4) + nitrobenzene (PhNO2) have been measured at 298.15 K. Limiting molar conductances Λ0, association constants KA, and cosphere diameter R for ion pair formation in the mixed solvent mixtures have been evaluated using the Lee−Wheaton conductivity equation. However, the deviation of the conductometric curves (Λ versus √c) from linearity for the electrolytes in 80 mass % of CCl4 + PhNO2 indicated triple ion formation, and therefore corresponding conductance data have been analyzed by the Fuoss−Kraus theory of triple ions. Limiting ionic molar conductances λ0± have been calculated by the reference electrolyte method along with a numerical evaluation of ion pair and triple ion formation constants (KP ≈ KAand KT); the results have been discussed in terms of solvent properties and configurational theory.

Diffusion NMR studies on neutral and cationic square planar palladium(II) complexes

Diffusion NMR investigations were carried out in CD 2Cl 2 for a series of neutral ( 1– 7) and cationic ( 8– 10) square planar palladium complexes. Diffusion data were elaborated through a modified Stokes–Einstein equation that takes into account the size and shape of molecules. The hydrodynamic volume at infinite dilution of all complexes was found to be similar to the crystallographic volume and always much larger than the van der Waals volume. The self-aggregation tendency of [Pd(N,C −)( N, N)][PF 6] ionic complexes [(N,C −) = (C 6H 4-(Ph)C(O)-C N-Et); 8, ( N, N) = 2,2′-bipirydine; 9, ( N, N) = (2,6-( iPr) 2-C 6H 3)N C(Me)-C(Me) N(2,6-( iPr) 2-C 6H 3); 10, ( N, N) = (2,6-( iPr) 2-C 6H 3)N C(R′)-C(R′) N(2,6-( iPr) 2-C 6H 3), R′ 2 = naphthalene-1,8-diyl] was investigated by performing 1H and 19F diffusion experiments as a function of the concentration. Clear evidence for the formation of ion triples containing two cationic units was obtained for 8, most likely due to the establishment of a weak Pd⋯O interaction. The tendency to form ion triples was much reduced in 9 and 10, having an increased steric hindrance in the apical positions. While 9 showed the usual tendency to afford a mixture of free ions and ion pairs, solvated ions were the predominant species in the case of 10 even at high concentration values (approaching 100 mM).

Molecular mobility and Li+ conduction in polyester copolymer ionomers based on poly(ethylene oxide)

We investigate the segmental and local dynamics as well as the transport of Li(+) cations in a series of model poly(ethylene oxide)-based single-ion conductors with varying ion content, using dielectric relaxation spectroscopy. We observe a slowing down of segmental dynamics and an increase in glass transition temperature above a critical ion content, as well as the appearance of an additional relaxation process associated with rotation of ion pairs. Conductivity is strongly coupled to segmental relaxation. For a fixed segmental relaxation frequency, molar conductivity increases with increasing ion content. A physical model of electrode polarization is used to separate ionic conductivity into the contributions of mobile ion concentration and ion mobility, and a model for the conduction mechanism involving transient triple ions is proposed to rationalize the behavior of these quantities as a function of ion content and the measured dielectric constant.

Intense white upconversion emission in Pr/Er/Yb codoped tellurite glass

Near infrared sensitized white light emitting glass has been developed and demonstrated. The white light comes from a combination of radiations emitted from triple rare earth ions (Er, Pr, and Yb) doped in tellurite glass. White light emission is possible by suitably mixing the red-green-blue (RGB) intensities emitted from these rare earth ions. The 980 nm radiation sensitized Yb3+ ions transfer their excitation energy to the Er3+ and Pr3+ ions to promote them to the upper states. The green and red emissions come mainly from Er3+ ion whereas blue emission from Yb3+ and Pr3+ ions. The RGB intensities could be adjusted by tuning the rare earth ion concentration. The optical quality of white light was adjudged using the Commission Internationale de l’ Eclairage coordinates by the rare earth ion concentration and incident power density.

Electron ionization of H2O

Relative partial ionization cross-sections and precursor-specific relative partial ionization cross-sections for fragment ions formed by electron ionization of H2O have been measured using time-of-flight mass spectrometry coupled with a 2D ion coincidence technique. We report data for the formation of H+, H2+, O2+, O+ and OH+ relative to the formation of H2O+, as a function of ionizing electron energy from 30 to 200eV. This data includes, for the first time, measurements on the formation all positive ion pairs and ion triples by dissociative multiple electron ionization of H2O. Through determinations of the kinetic energy release involved in ion pair formation we provide further evidence that indirect processes contribute significantly to the yield of H++OH+ ion pairs below the vertical double ionization threshold.

Ion-Pair and Triple-Ion Formation by Some Tetraalkylammonium Iodides in Binary Mixtures of 1,4-Dioxane + Tetrahydrofuran

Electrical conductances of tetraalkylammonium iodides, R4NI (R = pentyl to heptyl) have been measured at 298.15 K in low-permittivity mixtures of 1,4-dioxane (ε = 2.21) and tetrahydrofuran (ε = 7.58). Minima in the conductometric curves (Λ versus √c) were observed for electrolyte concentrations dependent upon both the electrolyte and the binary solvent mixture. The conductance data have been analyzed by the Fuoss−Kraus theory of triple ions. A numerical evaluation of ion-pair and triple-ion formation constants (KP and KT) was made, and the results have been discussed in terms of a molecular scale model.

The Possible Presence of Triple Ions in Electrolyte Solutions of Low Dielectric Permittivity

The cause of the appearance of a minimum in the molar electrical conductivity in many electrolyte solutions with increasing electrolyte concentration, in solvents of low dielectric permittivity, is reviewed. Tentative explanations include the formation of triple ions or, alternatively, changes in the electrical polarization of the solutions due to the presence of electrolyte ion pairs. Theoretical models for linear triple ions and apolar dimers are examined. Experimental evidence favors the polarization hypothesis over triple ions; the presence of a maximum in the dielectric permittivity with increasing electrolyte concentration is consistent with the presence of an equilibrium between ion pairs, AB, and their dimers, A2B2, at higher concentrations.

Ion Association and Solvation Behavior of Some Lithium Salts in Tetrahydrofuran. A Conductivity and Raman Spectroscopic Study

Accurate measurements of electrical conductivities and laser Raman spectra of solutions of lithium chloride (LiCl), lithium bromide (LiBr), lithium tetrafluoroborate (LiBF4) and lithium perchlorate (LiClO4) in tetrahydrofuran are reported. The conductivity data have been analyzed by the Fuoss-Krauss theory, yielding values for the ion-pair and triple-ion formation constants. The Raman spectra suggest the presence of a new signal of perchlorate ClO4− ions in solution, whereas there is no such evidence for the other investigated anions. The observed processes have been interpreted by an Eigen multistep mechanism. For each salt, the predominant portion is found to remain in the form of ion pairs, leaving only a small fraction of triple ions.

Electron ionization of CO 2

Relative partial ionization cross-sections (PICS) and precursor-specific relative partial ionization cross-sections for fragment ions formed by electron ionization of CO 2 have been measured using time-of-flight mass spectrometry (TOFMS) coupled with a 2-D ion-coincidence technique. We report data for the formation of C +, O +, CO +, C 2+, O 2+ and CO 2 2+ relative to the formation of CO 2 +, as a function of ionizing electron energy from 30 to 200 eV. This data includes, for the first time, measurements on the formation of ion triples by dissociative multiple ionization of CO 2 by electrons. Our analysis of the 2-D coincidence spectra provides new information on the dynamics and energetic of charge separating dissociation of the CO 2 dication and trication. Through determinations of the kinetic energy release (KER) involved in ion pair formation, we also conclude that indirect double ionization processes contribute significantly to the yield of CO + + O + ion pairs at ionizing electron energies below 55 eV.

Theoretical Studies of Carbocations in Ion Pairs. 8. Search for Anchimeric Assistance in the Ionization of 2-Butyl Cation Precursors

The structures of carbocations formed in the ionization of 2-butyl precursors were investigated by high level ab initio MO calculations on the reaction of 2-butyl fluoride (1) with borane, which gives a C4H9+ cation paired with trihydrofluoroborate (FBH3-, A). Two conformations of the "open," secondary cation (2) in the ion pair resulted from two conformations of 1, with F gauche and trans to C4 (2-g and 2-t, respectively). No anchimeric assistance by hydrogen (in 1-g) or methyl (in 1-t) was evidenced. In fact, attempts at optimizing the geometry of the H-bridged (3) and methyl-bridged (6) cations at short interionic distances (d) led to the corresponding conformations of 2. Upon ion separation, proton transfer from 2 to the anion occurred at intermediate interionic distances, consonant with experimental observations in trifluoroacetic acid. Elimination was prevented by addition of a lithium cation to the ion pair, i.e., running computations on triple ions (2.A.Li+). Cation 6 became an energy minimum beyond d = 2.5 A and 3 beyond 2.8 A. Cation 2-g was still the most stable isomer at d = 3.2 A, which was greater than the interionic distance in the crystals of the isomeric tert-butyl cation salts (3-3.1 A). Thus, spectral determinations of 2-butyl cations in the solid state should be interpreted with 2-g as the main component of the ion mixture. When the ions became separated (d >/= 4 A), only the bridged ions were energy minima. In this process, bridging did not occur opposite to the leaving group to assist the ionization, but on the same side with it, being controlled by the electrostatic interaction with the anion, as it departed from the vicinity of the cation. Such behavior was also noted in the ionization of the 3-methyl-2-butyl homolog.

Elucidation of specific ion association in nonaqueous solution environments

Abstract The paper reviews ion aggregation in ionic solution in solvents of low and high permittivity. Although higher ion aggregates from 1:1 type electrolytes in low-pemittivity media (εr < 10) are widely accepted, only a few chemists have recognized the higher ion aggregation in the higher-permittivity media. However, we have clarified that the chemical interaction, such as coordination, can operate between simple anions and cations in nonaqueous solvents (20 < εr < 65) of low solvation ability. Acids (HA) and their conjugate base anions (A-) may react with each other to form homoconjugated species, such as A-(HA)2, in acetonitrile or benzonitrile (i.e., solvents possessing poor hydrogen-bonding donor and acceptor abilities). An analytical method of conductivity data for 1:1 electrolytes has been developed and successfully applied to very complicated systems, in which the ion pair (1:1), triple ions (2:1 and 1:2), and the quadrupole (2:2 association) are involved in a solution at the same time. After observing the direct reaction of some anions (e.g., Cl-) and cations (e.g., Li+) toward a certain species, we interpreted comprehensively the salt effects in chemical equilibria, based on distinct chemical interactions and not merely a vague term, "medium effect". The mechanism of salt effects on solvolysis reactions of the SN1 type in organic-aqueous mixed solvents has been elucidated. We discussed that a reaction manner similar to that in nonaqueous solution can take place even in some "aqueous" solution if the huge network of hydrogen-bonding of bulk water (the number of water, n w > ~108) is destroyed due to any spatial barriers (such as ions, molecules, surface) or elevated temperature.

1,1′-(Butane-1,4-diyl)diimidazolium dinitrate

In the title compound, C10H16N4 2+·2NO3 −, the organic cation is located around an inversion centre. The imidazolium ring forms a dihedral angle of 62.7 (3)° with the plane defined by the C atoms of the –(CH2)4– aliphatic linker. Two anions bind to the cation via three-centre N—H⋯O hydrogen bonds and thus discrete hydrogen-bonded ion triples are formed. The nitrate is approximately coplanar with the imidazolium ring to which it binds.

From Ion Pairs to Ion Triples through a Hydrogen Bonding-Driven Aggregative Process

Complexes [Ru(arene)(κ3-dpk-OR]X (dpk = 2,2‘-dipyridylketone) were synthesized, and their interionic structure was investigated through an integrated approach based on diffusion and NOE NMR experiments and X-ray single-crystal studies. PGSE NMR results indicated that the highest aggregation tendency occurred for complex 2BF4 (arene = p-cymene and R = OH) that showed aggregation numbers consistent with the main presence of 22BF4+ ion triples (N+ = 1.9 and N- = 1.1, in CD2Cl2 at 0.5 mM). X-ray investigations indicated that a [1 × 1] network of HBs is present involving the two OH moieties of the two cationic fragments belonging to the two independent ion pairs of the asymmetric unit. This dication is likely the central moiety of 22BF4+ ion triples. According to 19F,1H-HOESY NMR interionic studies, the counterion was close to two pyridyl rings belonging to two different cations undergoing a π−π-stacking interaction in CD2Cl2 exactly as observed in the solid state. All of the other complexes having an alyphati...

Bis(triethylammonium) tetrachloridomanganate(II)

The title compound, (Et3NH)2[MnCl4], was obtained unexpectedly in an attempt to prepare a carboxyl­ate-bridged coordination network. It is the first reported structure of a tertiary ammonium salt of the tetra­hedral [MnCl4]2− anion (Table 1). Each of the two crystallographically independent cations forms an N—H⋯Cl hydrogen bond to the anion (Table 2), generating discrete ion triples. The Mn—Cl bonds involving the hydrogen-bonded Cl atoms are longer than the others.

Self-diffusion versus ion conduction in polymer electrolytes: On the occurrence of pairs, triplets, and higher-order clusters

We show that the ion transport properties previously established for several amorphous polyether-based electrolytes by tracer diffusion and conductivity measurements cannot be exclusively explained by triple ions or higher-order ionic clusters as the most significant mobile species. A combined analysis of the tracer diffusion and conductivity data at different concentrations and temperatures rather indicates that charged single ions and neutral ion pairs play a prominent role. In particular, it is found that the single anion controls the transport of negative charge. Allowing for positive and negative charge carriers of various size, the analysis is based on upper and lower limits derived for the charge diffusivity D σ with respect to the cation and anion tracer diffusivity. The derived expressions have a general validity and may be applied to any electrolyte system for which a complete set of mass and charge transport data is available.