Solvent extraction of H3O+, NH4+, Ag+, K+, Rb+ and Tl+ into nitrobenzene by using cesium dicarbollylcobaltate in the presence of a hexaarylbenzene-based receptor

From extraction experiments and γ-activity measurements, the extraction constants corresponding to the general equilibrium M⁺(aq) + 1·Cs⁺(nb) \rightleftarrows \rightleftarrows 1·M⁺(nb) + Cs⁺(aq) taking part in the two-phase water–nitrobenzene system (1 = hexaarylbenzene-based receptor; M⁺ = H₃O⁺, NH₄ ⁺, Ag⁺, K⁺, Rb⁺, Tl⁺; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML⁺ complex species in nitrobenzene saturated with water were calculated; they were found to increase in the series of Rb⁺ < K⁺ < Ag⁺, Tl⁺ < H₃O⁺, NH₄ ⁺.     

Energy disposal in thermal-energy charge-transfer reactions: Ar+,Kr+ and Xe+ with NH3

Thermal-energy charge-transfer reactions from the ²P_3/2 state of Ar⁺, Kr⁺ and Xe⁺ with NH₃ are shown to be non-energy resonant: the kinetic energy released in each case has been measured, and the internal energy of the NH⁺₃ product ions deduced. Possible quenching of ²P_1/2 state of rare-gas ions in ICR cells is discussed.     

Stability constants of the Li+, Na+, H3O+, NH4+, Ag+, and K+ complexes of the cone conformer of tetraethyl p-tert-butyltetrathiacalix[4]arene tetraacetate in nitrobenzene saturated with water

Abstract  

From extraction experiments in the two-phase water–nitrobenzene system and γ-activity measurements, the stability constants of the tetraethyl p-tert-butyltetrathiacalix[4]arene tetraacetate (cone)·M⁺ complexes (M⁺ = Li⁺, H₃O⁺, NH₄ ⁺, Ag⁺, or K⁺) were determined in water-saturated nitrobenzene. It was found that these constants increase in the cation order NH₄ ⁺ < K⁺ < H₃O⁺ < Ag⁺ < Li⁺ < Na⁺.     

Stability constants of complexes of Li+, H3O+, NH 4+ and Ag+ with hexaethyl calix[6]arene hexaacetate in nitrobenzene saturated with water

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺(aq)+NaL⁺(nb)⇔ML⁺(nb)+Na⁺(aq) taking place in the two-phase water-nitrobenzene system (M⁺ = Li⁺, H₃O⁺, NH₄⁺, Ag⁺; L = hexaethyl calix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were determined. Furthermore, the stability constants of the ML⁺ complexes in water saturated nitrobenzene were calculated; they were found to increase in the cation order H₃O⁺<NH₄⁺<Li⁺<Ag⁺.     

Discussion on complexation reactions between dicyclohexyl-18-crown-6 (DCH18C6) with Na+, K+, Cs+, Rb+, and Tl+ metal cations in acetonitrile-water binary mixtures

The complex formation between Na⁺, K⁺, Cs⁺, Rb⁺ and Tl⁺ metal cations with macrocyclic ligand, dicyclohexyl-18-crown-6 (DCH18C6) was studied in acetonitrile-water (AN-H₂O) binary systems at different temperatures using conductometric method. DCH18C6 forms 1:1 complexes with these metal cations. The stability constants of the complexes were obtained from fitting of molar conductivity curves using a computer program Genplot. The results show that the selectivity order of DCH18C6 for the metal cations in acetonitrile-water mixtures (AN = 25.3 and 50.4 mol %) is: Tl⁺ > K⁺ > Rb⁺ > Cs⁺ > Na⁺. A non-linear behaviour was observed between the log K _f of the complexes versus the composition of the mixed solvent which it related to changes of acidity, basicity, polarity and also polarizability of AN-H₂O mixtures with the composition of this binary solution. The values of standard enthalpy changes (ΔH _s⁰) for complexation reactions were obtained from the slope of the van’t Hoff plots and the changes in the standard entropy (ΔS _s⁰) were calculated from the relationship: ΔG _s,298.15⁰ = ΔH _s⁰ − 298.15ΔS _s⁰. The obtained results show that in most cases, the complexes are enthalpy stabilized but entropy destabilized. Original Russian Text ? M.H. Soorgi, G.H. Rounaghi, M.S. Kazemi, 2008, published in Zhurnal Obshchei Khimii, 2008, vol. 78, No. 10, pp. 1627–1632.     

An ab initio potential energy surface for the reaction N+ + H2 → NH+ + H

Preliminary results of ab initio unrestricted Hartree-Fock calculations for the potential energy surface for the reaction N⁺ + H₂ → NH⁺ + H are reported. For the collinear approach of N⁺ to H₂, the ³Σ^? surface has no activation barrier and has a shallow well (ca. 1 eV). For perpendicular approach (C_2v symmetry) the ³B₂ state is of high energy, the ³A₂ state has a shallow well but as the bond angle increases the ³B₁ state decreases in energy to become the state of lowest energy. Neither the collinear nor the perpendicular approaches give adiabatic pathways to the deep potential well of ³B₁ (HNH)⁺.     

Ab initio MO calculations on the stable conformations and their binding energies of the ion-molecule complexes: Ion = H+, Li+, Na+, K+ Be2+, and molecule = CO and N2

The most stable conformation of ion-molecule complexes involving a CO molecule were surveyed by the use of Hartree-Fock (HF) MO and third-order Moller-Plesset perturbation (MP3) methods with a 6–31G* basis set ion = H⁺, Li⁺, Na⁺, K⁺, Bc²⁺, Mg²⁺, and Ca²⁺. The MP3 level of theory reveals the ion-CO conformation in which the ion bonds to a carbon atom of CO to be the most stable; these MP3 results are contrary to the HF ones. Binding energies of ion-molecule complexes involving CO and N₂ were computed; MP3 energies are in good agreement with the experimental ones. The computed binding energies of cation-N₂ are about one-third of cation-NH₃ due to the absence of dipole moment and the smaller polarizability of N₂. The decrease in binding energy in cation-CO and -N₂ complexes, with increasing cation size, is mainly caused by the decrease of the electrostatic and polarization stabilizations.     

Thermogravimetry of the analytical precipitates M2Pb[Co(NO2)6] AND MPb[Co(NO2)6]

Thermogravimetric studies are reported for analytical precipitates of the types MPb[Co(NO₂)₆] and M₂Pb[Co(NO₂)₆], where M represents the univalent cations NH⁺₄, K⁺, Rb⁺, Cs⁺, and Tl⁺. Compounds of the latter series are consitently more stable to higher temperatures. For either series increasing the radius of M increases thermal stability. Decomposition to temperatures approaching 500°C involves some four separate processes.     

Pulsed NMR study of NH4+ β-alumina

Proton NMR relaxation times T₂, T₁, and T_1? are reported for NH₄⁺ β-alumina powder in the temperature range 77 K < T < 500 K at 16 MHz. The measurements show that the NH₄⁺ ions both reorient and translate. The translational process can be characterized by the parameters E = 20 kJ mole^?1 and τ⁰_d = 3 × 10^?11 sec. Relaxation at high temperatures is dominated by dipolar coupling to paramagnetic impurities. Reasons for the different activation energies measured using NMR and other techniques for β-alumina compounds are discussed.     

ESR spectra and magnetic constants of α-Al2O3:Co2+,H+ and α-Al2O3 :Co2+,X+

New anisotropic ESR spectra of Co²⁺ doped sapphire, different from hitherto known, are reported. The new spectra which are observed, beside the well-known spectra of α-Al₂O₃:Co²⁺, are shown to form two sets, each one consisting of six spectra (1–6) and (7–12). The spectra of both sets are proven to be interrelated by B_3a symmetry. g and A tensors for each set will be given. Evidence is given that the two sets are to be assigned to the defects α-Al₂O₃:Co²⁺,H⁺ and α-Al₂O₃:Co²⁺,X⁺. The former is concluded to consists of a Co²⁺ ion at the substitutional site (c) and a proton located in a potential minimum along a straight line between O^2- ions situated in O²⁺ triangles above and below the CO²⁺ ion. The potential function for the proton has been calculated by quantum-chemical calculations to clucidate the geometrical structure of the paramagnetic center. The α-Al₂O₃:Co²⁺,X⁺ could not be fully analyzed but some evidence is presented, that X⁺ might be alkali ions.     

钙钛矿结构荧光材料MZrO3:Eu3+,A (M=Ca2+, Ba2+; A=Li+, Na+, K+)的制备及其发光性质

Calcium and barium zirconate powders based upon CaZrO₃:Eu³⁺,A and BaZrO₃:Eu³⁺,A (A=Li⁺, Na⁺, K⁺) were prepared by combustion synthesis method and heating to ~1000℃ to improve crystallinity.The structure and morphology of materials were examined by X-ray diffraction (XRD) and scanningelectron microscopy (SEM). XRD results showed that CaZrO₃:Eu³⁺,A and BaZrO₃:Eu³⁺,A (A=Li⁺, Na⁺, K⁺) perovskites possessed orthorhombic and cubic structures, respectively. The morphologies of all powderswere very similar consisting of small, coagulated, cubical particles with narrow size distributions andsmooth and regular surfaces. The characteristic luminescences of Eu³⁺ ions in CaZrO₃:Eu³⁺,A (A=Li⁺, Na⁺, K⁺) lattices were present with strong emissions at 614 and 625 nm for ⁵D₀→⁷F₂ transitions with other weakeremissions observed at 575, 592, 655, and 701 nm corresponding to ⁵D₀→⁷F_n transitions (where n=0, 1, 3, 4 respectively). In BaZrO₃:Eu³⁺ both the ⁵D₀→⁷F₁ and ⁵D₀→⁷F₂ transitions at 595 and 613 nm were strong.Photoluminescence intensities of CaZrO₃:Eu³⁺ samples were higher than those of BaZrO₃:Eu³⁺ lattices. Thisremarkable increase of photoluminescence intensity (corresponding to ⁵D₀→⁷F_n transitions) was observedin CaZrO₃:Eu³⁺ and BaZrO₃:Eu³⁺ if co-doped with Li⁺ ions. An additional broad band composed of manypeaks between 440 to 575 nm was observed in BaZrO₃:Eu³⁺,,A samples. The intensity of this band wasgreatest in Li⁺ co-doped samples and lowest for K⁺ doped samples.     

Internal-energy-selected measurements on the relative cross section of the ion-molecule reaction NH3+(NH3, NH2)NH4+

A photoelectron-photoion coincidence technique is used to measure the internal-energy dependence of the ion-molecule reaction NH₃⁺(E_int+NH₃ → NH₄⁺ + NH₂ at thermal collision energy. The range in which the internal energy is varied, is enlarged by including in the experiment the electronically excited state of the NH₃⁺ ion. Special attention is paid to the possible influence of the product's kinetic energy on the measurements. The experimental results are analysed using a modified statistical model and compared with previous data.     

Chemical composition and crystal structure of β-alumina type R+-gallate (R+ = K+, NH+4)

The crystal structures of β-alumina type K⁺-gallate (K⁺-β-gallate), Mg²⁺-doped K⁺-β-gallate, and NH⁺₄-β-gallate were refined by the single crystal X-ray diffraction method. The positive charges of excess K⁺ ions in K⁺-β-gallate were compensated by O^2? ions in the mO site which coordinated with interstitial Ga³⁺ ions. The charge compensation mechanism mentioned above was changed by doping with Mg²⁺ ions. The excess charges in Mg²⁺-doped K⁺-β-gallate were compensated by the replacement of Mg²⁺ ions for Ga³⁺ ions at the middle of spinel block. No defects were found in NH⁺₄-β-gallate for the charge compensation, which was completely consistent with the result of thermal analysis that indicated a stoichiometric composition of NH⁺₄-β-gallate.     

A kinetic study of proton transfer reactions of NH+4, CH3NH+3, and PH+4 with calcium atoms

Cross section measurements for the proton transfer reactions of NH⁺₄, CH₃NH⁺₃, and PH⁺₄ with Ca(g) have been obtained over a range of low ion kinetic energies. For all reactions studied the cross sections drop sharply with increase in ion kinetic energy, indicating exothermic behavior. The results show that Ca(g) is an unusually strong base with a proton affinity in excess of 9.2 eV. Cross sections for the PH⁺₄Ca reaction are an order to magnitude higher than those for the NH⁺₄Ca reaction for ion energies between one and three eV. This effect is not explained by simple theories of ion-induced dipole interactions. It is suggested that the enhanced rate of the PH⁺₄Ca reaction may be due to d-orbital participation.     

A thermodynamic study of complex formation between dicyclohexyl-18-crown-6 (DCH18C6) and La3+, UO 22+ , Ag+, and NH 4+ cations in acetonitrile-tetrahydrofuran binary media using conductometric method

The complex formation between La³⁺, UO₂²⁺ Ag⁺, and NH₄⁺ cations and macrocyclic ligand, dicyclohexyl-18-crown-6 (DCH18C6), was studied in acetonitrile-tetrahydrofuran (AN-THF) binary mixtures at different temperatures using the conductometric method. The results show that with the exception of complexation of the NH₄⁺ cation with DCH18C6 in pure acetonitrile, the stoichiometry of all the complexes is being 1: 1 (M: L). The stability constants of the complexes were determined using a GENPLOT computer program. The nonlinear behavior which was observed for changes of log K _f of the complexes versus the composition of the mixed solvent was discussed in terms of solvent-solvent interaction in their binary solution, which results in changing the chemical and physical properties of the constituent solvents when they mix with one another and, therefore, changing the solvation capacities of the metal cations, crown ether molecules, and even the resulting complexes with changing the mixed solvent composition. The results show that the selectivity of DCH18C6 for the studied cations changes with the composition of the AN-THF binary system. The sequence of stabilities of complexes in an AN-THF binary solution (mol. % AN = 75.0) at 25°C is [(DCH18C6)La)]³⁺ > [(DCH18C6)UO₂]²⁺ > [(DCH18C6)Ag]⁺ ∼ [(DCH18C6)NH₄]⁺, but in the case of other binary systems of AN/THF (mol. % AN = 25.0 and 50.0) is [(DCH18C6)La]⁺ > [(DCH18C6)NH₄]⁺ ∼ [DCH18C6)UO₂]²⁺ > [(DCH18C6)Ag]⁺. The text was submitted by the authors in English.     

Rotational analysis of the a3Π0+,1-X1Σ+ emission systems of GeH+

New emission systems have been observed from the helium afterglow reaction of GeH₄ in the 520–610 nm region. On the basis of the rotational analysis, they were assigned to the a ³Π_0⁺-X¹Σ⁺ and a³Π₁-X¹Σ⁺ subsystems of GeH⁺. Spectroscopic constants have been determined for the GeH⁺ (a³Π_0⁺, a³Π₁, X¹Σ⁺) states.     

Ã2Σ+ → X̃+Π Emission spectra of the phosphaethyne cations,HCP+ and DCP+

The electron impact excited òΣ⁺ → X?⁺Π emission spectra of HCP⁺ and DCP⁺ have been observed. The spin-orbit split 0-0 band has maxima at 593.7 and 599.0 nm for HCP⁺ and 593.6 and 598.8 nm for DCP⁺. Short progressions in the V₃(CP) vibration are observed. a₀, v₃ and the upper-state lifetime are determined.     

Sorption behaviour of rubidium,thallium and silver on chromium ferricyanide gel binary separations of Rb+ and Tl+

Sorption behaviour of monovalent Rb⁺, Tl⁺ and Ag⁺ is studied on chromium fericyanide gel. Log K_d vs log concentration plots show that Rb⁺ and Tl⁺ are sorbed through ion exchange mechanism in a higher concentration range of ammonium nitrate or nitric acid, whereas the adsorption of Ag⁺ is irreversible. It was found possible to elute Rb⁺ and Tl⁺ on the columns of this gel by 4 mol dm⁻³ NH₄NO₃ and 10 mol dm⁻³ HNO₃, respectively. Binary separations of Rb⁺ and Tl⁺ from a number of other metal ions were achieved as other ions were found practically unadsorbed on these columns and were eluted with water of pH 2–3. Achieved separations are of radioanalytical and analytical importance.     

Coincidence studies of fluorescence and dissociation processes in electronic excited states of I2+, Br2+, IBr+ and ICl+

The PIFCO technique in which mass-selected photoion—fluorescence photon coincidences are counted, was used to investigate whether I₂⁺, IBr⁺ and ICl⁺ fluoresce. Measurements were made of lifetimes and fluorescence quantum yields of electronic excited states of these ions. Emission was discovered for I₂⁺ and IBr⁺, but ICl⁺ apparently does not fluoresce. Information on the radiative properties of Br₂⁺ was obtained as a by-product of the work on IBr⁺. Fragment ion kinetic energy releases were determined and provide information on dissociative ionization processes in the halogen and interhalogen ions studied.     

Electric moments,polarizabilities and hyperpolarizabilities for BH(X1Σ+ and CH+ (X1Σ+)

The electric moments and static polarizabilities of BH(1σ²2σ²3σ², X¹Σ⁺) and CH⁺ (1σ²2σ²3σ², X¹Σ⁺) were calculated at the experimental internuclear separation in the LCAO SCF MO approximation. Most of the molecular properties reported in this paper for BH and CH⁺ appear for the first time and should be close to the Hartree—Fock limit. All tensors up to the fourth rank have been included in this study. The isotropy and anisotropy of the α, β and γ tensors are, in atomic units. $\text{α}$ = 22.71, Δα = ?0.26, $\text{β}$ = 55.1, Δβ = ?183.7, $\text{γ}$ = 12428, Δ₁γ = 37895, Δ₂γ = 25120 for BH and $\text{α}$ = 7.73, Δα = 0.39, $\text{β}$ = ?12.4, Δβ = ?11.7, $\text{γ}$ = 344, Δ₁γ = 1515, Δ₂γ = 750 for CH⁺.