Redox behavior of $${\text{VO}}^{2 + } / {\text{VO}}_{2}^{ + }$$ as a simulant of $${\text{NpO}}_{2}^{ + } / {\text{NpO}}_{2}^{2 + }$$NpO2+/NpO22+ in boiling nitric acid solution

To evaluate the redox behavior of \({\text{VO}}^{2 + } / {\text{VO}}_{2}^{ + }\) as a simulant of \({\text{NpO}}_{2}^{ + } / {\text{NpO}}_{2}^{2 + }\) in boiling nitric acid solution, i.e., typical operating conditions for nuclear fuel reprocessing plants, oxidation rate measurements for VO²⁺ in boiling and non-boiling nitric acid solutions, thermodynamic calculations, and kinetic calculations were performed. The results indicated that the apparent oxidation rate of VO²⁺ to \({\text{VO}}_{2}^{ + }\) is accelerated by a decrease in \({\text{NO}}_{2}^{ - }\) and HNO₂ concentrations owing to the boiling phenomena of nitric acid solution.     

Study of $${\text{CD}}_{5}^{ + }$$ Ions and Deuterated Variants( $${\text{C}}{{{\text{H}}}_{x}}{\text{D}}_{{(5 - x)}}^{ + }$$ ): An Artefactual Rotation

Russian Journal of Physical Chemistry A - Deuterated methane, $${\text{CD}}_{5}^{ + }$$ , has unusual vibrational and rotational behavior because its three nonequivalent equilibrium structures have...     

Electrochemical Detection of ClO$\rm{ {_{3}^{-}}}$, BrO$\rm{ {_{3}^{-}}}$, and IO$\rm{ {_{3}^{-}}}$ at a Phosphomolybdic Acid Linked 3‐Aminopropyl‐Trimethoxysilane Modified Electrode

A composite film modified electrode containing a Keggin‐type heteropolyanion, H₃(PMo₁₂O₄₀)?H₂O, was fabricated with 3‐aminopropyltrimethoxysilane (APMS) attached on an electrochemically activated glassy carbon (GC) electrode through the formation of C? O? Si bond. PMo₁₂O was then complexed with APMS through the electrostatic interaction between the phosphate groups of PMo₁₂O and amine groups of APMS (PMo₁₂O ‐APMS). XPS and cyclic voltammetry were employed for characterization of the composite film. The PMo₁₂O ‐APMS modified electrode showed three reversible redox pairs with smaller peak‐separation and was stable in the larger pH range compared with that in a solution phase. The catalytic properties of the modified electrode for the reduction of ClO , BrO , and IO were studied and the modified electrode exhibited good electrocatalytic activities for the three anions. The experimental parameters, such as pH, temperature, and the applied potential were optimized. The detection limits were determined to be 7.0±0.35 μM, 4.0±0.17 μM, and 0.1±0.04 μM for ClO , BrO , and IO , respectively. The modified electrode was applied to natural water samples for the detection of ClO , BrO , and IO .     

Structures and formation of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm 8}} } \right]_{}^{_.^ + } $\end{document} ions

Several \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm\ 8}} } \right]_{}^{_.^ + } $\end{document} ion isomers yield characteristic and distinguishable collisional activation spectra: \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 1-butene} } \right]_{}^{_.^ + } $\end{document} and/or \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm 2-butene} } \right]_{}^{_.^ + } $\end{document} (a-b), \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm isobutene} } \right]_{}^{_.^ + } $\end{document} (c) and [cyclobutane]⁺ (e), while the collisional activation spectrum of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm methylcyclopropane} } \right]_{}^{_.^ + } $\end{document} (d) could also arise from a combination of a-b and c. Although ready isomerization may occur for \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 4}} {\rm H}_{{\rm 8}} } \right]_{}^{_.^ + } $\end{document} ions of higher internal energy, such as d or e → a, b, and/or c, the isomeric product ions identified from many precursors are consistent with previously postulated rearrangement mechanisms. 1,4-Eliminations of HX occur in 1-alkanols and, in part, 1-buthanethiol and 1-bromobutane. The collisional activation data are consistent with a substantial proportion of 1,3-elimination in 1- and 2-chlorobutane, although 1,2-elimination may also occur in the latter, and the formation of the methylcycloprpane ion from n-butyl vinyl ether and from n-butyl formate. Surprisingly, cyclohexane yields the \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm linear butene} } \right]_{}^{_.^ + } $\end{document} ions a-b, not \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm cyclobutane} } \right]_{}^{_.^ + } $\end{document}, e.     

Gas phase isomerization of \documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 10}} {\rm H}_{{\rm 14}} } \right]_{}^{_.^ + } $\end{document} ions generated from adamantanoid compounds

\documentclass{article}\pagestyle{empty}\begin{document}$ \left[{{\rm C}_{{\rm 10}} {\rm H}_{{\rm 14}} } \right]_{}^{_.^ + } $\end{document} ions have been generated from a number of adamantanoid compounds, both by ionization and ionization followed-by fragmentation. Metastable ion abundance ratios of competitive reactions indicate the decomposition of these ions from common structures in all cases.     

Solid-state Structures and Solution Behavior of Alkali Salts of the [\hbox{Nb}_{6}\hbox{O}_{19}]^{8-} Lindqvist Ion

The hexaniobate Lindqvist ion has long been known as the dominant specie in alkaline niobium oxide solutions. Recent advances in heteropolyniobate chemistry continue to be greatly aided by use of alkali salts as soluble precursors; in particular, potassium, sodium and lithium hexaniobate salts. We report here the solid-state characterization and solution behavior of Li, K, Rb and Cs Lindqvist salts. Synthesis and single-crystal X-ray diffraction data is reported for nine new hexaniobate salts. These structures differ in the number of charge-balancing alkali cations, protonation of the clusters, relative arrangement of the clusters and alkali metal cations, amount of lattice water and its mode of interaction with other lattice species. Trends of alkali-cluster bonding are observed as a function of alkali radius. Protonation of the clusters in the solid-state is influenced by the method of crystallization of the salt. Lability of the cluster oxygens is observed by solution ¹⁷O NMR experiments. Rates of isotopic enrichment of the bridging oxygen, terminal oxygen and bridging hydroxyl cluster sites are compared for aqueous solutions of Li, K, Rb and Cs hexaniobate salts. Parameters influencing the oxo-ligand exchange rates of the salts are discussed relative to their use as heteropolyniobate precursors.This paper is dedicated to Professor Michael T. Pope on the event of his retirement to acknowledge his fruitful career in polyoxometalate chemistry.     

Extraction of $$ {\text{Np}}^{4+} $$ and $$ {\text{NpO}}_{2}^{2+} $$NpO22+ from Nitric Acid Medium Using TODGA in Room Temperature Ionic Liquids

Extraction of Np⁴⁺ and \( {\text{NpO}}_{2}^{2 + } \) was carried out from nitric acid feeds using solutions of N,N,N′,N′-tetra-n-octyldiglycolamide (TODGA) in two imidazolium-based room temperature ionic liquids, viz., 1-butyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide ([C₄mim][NTf₂]) and 1-octyl-3-methylimidazolium bis(trifluoromethanesulphonyl) imide ([C₈mim][NTf₂]). The extraction equilibrium was attained within 2 h for both the metal ions in both the ionic liquids. While a cation exchange mechanism is proposed for the extraction of \( {\text{NpO}}_{2}^{2 + } , \) an ion-pair mechanism of extraction is proposed for the Np⁴⁺ ion. The nature of the extracted species was determined by carrying out experiments at varying concentrations of TODGA, and species of the type Np(L)₂(NO₃)₄ and NpO₂(L)²⁺ were found to be extracted in 3 mol·dm^?3 HNO₃. The identification of these extracted species was also supported from the variable nitrate and C₄mim⁺ ion concentration experiments.     

Free ions Pr IV (4\text{ f }^{2}) and Tm IV (4\text{ f }^{12}): intermediate versus LS coupling scheme

The intermediate and LS-coupling schemes for the free lanthanide ions $\text{ Pr }^{3+}$ Pr 3 + and $\text{ Tm }^{3+}$ Tm 3 + have been compared by the matrix elements of the tensor operator ${{\varvec{U}}}^{({\varvec{k}})}, \text{ k } = 2, 4, 6$ U ( k ) , k = 2 , 4 , 6 . The necessary eigenvectors and eigenvalues have been computed with the aid of four parameters, $\text{ F }_{2}, \text{ F }_{4}, \text{ F }_{6}$ F 2 , F 4 , F 6 , and $\zeta _{4\mathrm{f}}$ ζ 4 f , known from free-ion spectra of the same ions. It has been found that both coupling types for each ion lead to close values of ${\vert }{{\varvec{U}}}^{({\varvec{k}})}{\vert }^{2}$ | U ( k ) | 2 only for transitions from the ground level to certain lower-lying energy levels within the $4\text{ f }^\mathrm{N}$ 4 f N configuration.     

Chiral Coordination Polymers with Amino Acids: $\rm ^{2}_{\infty}[Cu_{2}(\mu-L-tryptophanato)_{2}(\mu-4,4\prime-bipyridine)(H_{2}O)_{2}](NO_{3})_{2}$

The two‐dimensional mixed‐ligand network catena‐[(μ‐4,4′‐bipyridine)‐bis(μ‐L‐tryptophanato‐κ³N,O,O′)‐diaqua‐dicopper(II) dinitrate] is constructed through the bridging action of both the tridentate amino carboxylato and the bidentate 4,4′‐bipyridine ligand. The enantiomeric L‐tryptophanato ligand acts as an N,O chelate towards one copper atom and bridges through the second carboxylate oxygen atom to the adjacent copper ion. Stacking of the corrugated nets creates channels which are occupied by the hydrogen‐bonded and very weakly Cu‐coordinating nitrate ions.     

Voltammetric Behavior of MoS$\rm{ {_{4}^{2-}}}$ and SbS$\rm{ {_{4}^{3-}}}$ as Possible Components of “Dissolved Sulfide” in Oxic Natural Waters

Nanomolar concentrations of dissolved sulfide have been observed in O₂‐ bearing natural waters. The sulfide consists of oxidation‐resistant, unknown chemical components that might include metal‐sulfide complexes, elemental sulfur in various forms or organic sulfur compounds. Here we show that thioanions are also plausible components. Tetrathiomolybdate and tetrathioantimonate ions deposit respectively 3 and 4 equivalents of HgS at mercury electrodes. In cathodic stripping voltammetry, a common method to quantify nanomolar sulfide in nature, MoS and SbS would therefore contribute to “total dissolved sulfide.” Limited evidence suggests that thioanions may be powerful complexing agents that would be capable of affecting trace metal speciation and bioavailability in natural waters.     

On the topology of the electron density of ${\mathrm {H}}_{3}^{+}$

The topology of the electron density ρ(r) of \({\mathrm {H}}_{3}^{+}\) is revisited by series of ultra fine tuned geometry optimizations within Hartree-Fock self-consistent virial scaling (SCVS) approach in combination with correlation consistent cc-pVXZ basis sets. The calculations are extended to approach the Hartree-Fock complete basis set (CBS) limit. It is discussed that within such tuned ab initio calculations, the sources of errors that are mapped to the final density matrix in normal calculations are essentially eliminated. The results of electron density analysis on such error-free ρ(r) function via the quantum theory of atoms in molecules (QTAIM) confirm unambiguously the non-nuclear attractor (NNA) as the fundamental topological building block (together with three H atomic basins) to describe the bonding in \({\mathrm {H}}_{3}^{+}\) ion-molecule. The convergence patterns of the values of different density-dependent properties toward CBS limit are also explored. It is reported that the cc-pVXZ sets are not only energy-consistent but also density-consistent. Therefore, on the basis of this important density consistency behavior, the CBS limit values of different atomic and bonding indexes are estimated and ultimately the structure and bonding pattern of \({\mathrm {H}}_{3}^{+}\) are concluded.     

Layer-by-layer assembly of Ru3+ and $$ {\text{Si}}_{{\text{8}}} {\text{O}}^{{8 - }}_{{20}} $$ into electrochemically active silicate films

A porous silicate is obtained from octa-anionic cage-like poly-silicate (PS) and Ru³⁺ cations in an ethanol-based layer-by-layer assembly process. Electrochemical experiments (voltammetry and impedance spectroscopy) confirm the formation of redox-active ruthenium centers in the form of hydrous ruthenium oxide throughout the film deposit. Oxidation of Ru(III) to Ru(IV) at a potential below 0.5 V vs saturated Calomel electrode (SCE) is reversible, but a potential positive of 0.5 V vs SCE is associated with an irreversible change in reactivity, which is characteristic for very small hydrous ruthenium oxide nanoparticles. Further voltammetric experiments are performed in aqueous phosphate buffer solutions, and the effects of number of layers, scan rate, and pH are investigated. Three aqueous redox systems are studied in contact with the PS–Ru³⁺ films. The reduction of cationic methylene blue adsorbed onto the negative surface of the nanocomposite silicate is shown to occur, although most of the bound methylene blue appears to be electrochemically inactive either bound to silicate or buried into small pores. The PS–Ru³⁺-catalyzed oxidations of hydroquinone and arsenite(III) are investigated. Scanning electron microscopy images show that a macroscopically uniform porous surface is formed after deposition of 50 layers of the PS–Ru³⁺ nanocomposite. However, atomic force microscopy images demonstrate that in the initial deposition stages, irregular island growth occurs. The average rate of thickness increase for PS–Ru³⁺ nanocomposite films is 6 nm per deposition cycle.     

Quasi-classical trajectory insight into stereodynamics for reaction $$\hbox {He}+\hbox {D}_{2}^{+}\rightarrow \hbox {HeD}^{+}+\hbox {D}$$ with the improved potential energy surface

In this work, a theoretical study on the detailed vector correlation for the reaction \(\hbox {He}+\hbox {D}_{2}^{+}\rightarrow \hbox {HeD}^{+}+\hbox {D}~(\hbox {v}, \hbox {j})\) has been carried out at the collision energy of 23.06 kcal/mol with different rotational states of j \(=\) 0–5 and vibrational states v \(=\) 1–5 by use of the quasi-classical trajectory calculation on an improved potential energy surface. The features of \({{\varvec{P}}}\mathbf{(}{\varvec{\theta }}_{{\varvec{r}}}{} \mathbf{)}\) distributions describing k and \(\mathbf{j}^\prime \) correlations were discussed. In addition, in order to get full knowledge of stereodynamics of the system, the distributions of dihedral angle \({{\varvec{P}}}\mathbf{(}{\varvec{\varphi }}_{{\varvec{r}}}{} \mathbf{)}\) and the polarization-dependent differential cross-sections (PDDCSs) were also reported. It has been demonstrated that both product alignment and polarization are sensitive to the reagent vibrational and rotational number. Furthermore, the dynamics behavior of the reaction is independently changed with respect to j under a certain v except for the product alignment effect \(({\varvec{P}}({\varvec{\theta }}_{{\varvec{r}}}))\), while it exhibits a generally regular trend concerning v when j is invariable.