DFT studies on the structures and stabilities of N<Subscript>5</Subscript><Superscript>+</Superscript>-containing salts

Density functional theory (DFT) methods have been applied to study the properties of series of N₅ ⁺ salts. The thermal stabilities of the crystals are evaluated based on the reaction enthalpy (ΔH) and free energy change (∆G) of the salts when they dissociate into neutral products. The energy outputs of salts in explosion indicate that all N₅ ⁺ salts yield large energy except for N₅SbF₆ and N₅Sb₂F₁₁. Considering the released energy and thermal stability, (N₅)₂SnF₆, N₅PF₆, N₅BF₄, and N₅SO₃F may be potential candidates of very energetic explosives.     

Silicate complexation of NpO<Subscript>2</Subscript><Superscript>+</Superscript> ion in perchlorate media

Complexation behavior of NpO₂ ⁺ with ortho-silicic acid (o-SA) has been studied using solvent extraction at ionic strengths varying from 0.10 to 1.00M (NaClO₄) at pcH 3.68±0.08 and 25 °C with bis-(2-ethylhexyl) phosphoric acid (HDEHP) as the extractant. The stability constant value (log β₁) for the 1:1 complex, NpO₂(OSi(OH)₃), was found to decrease with increase in ionic strength of the aqueous phase [6.83±0.01 at I=0.10M to 6.51±0.02 at I = 1.00M]. These values have been fitted in the SIT model expression and compared with similar values of complexation of the metal ions Am³⁺, Eu³⁺, UO₂ ²⁺, PuO₂ ²⁺, Np⁴⁺, Ni²⁺ and Co²⁺. The speciation of NpO₂ ⁺-o-silicate/carbonate system has been calculated as a function of pcH under ground water conditions. On leave from Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085, India.     

Adducts of zinc and copper(II) dialkyldithiocarbamate complexes with dialkylamines: Synthesis,EPR, and <Superscript>13</Superscript>C and <Superscript>15</Superscript>N CP/MAS NMR

Crystalline adducts of zinc and copper(II) dithiocarbamate (Dtc) complexes with dialkylamines [M(NHR′₂)(S₂CNR₂)₂] (M = Zn, ⁶³Cu, ⁶⁵Cu; R = CH₃, C₂H₅, or R₂ = (CH₂)₄O; R′ = C₂H₅, C₃H₇) have been preparatively isolated. The structures and spectral properties of the adducts have been studied by EPR and ¹³C and ¹⁵N MAS NMR. Chemisorption of bases on powders of dinuclear dithiocarbamates leads to their dissociation into monomeric adducts. Computer simulation demonstrates that the experimental EPR spectra of isotope-substituted copper(II) adducts have an individual character. The geometry of the copper polyhedra is intermediate between a trigonal bipyramid (TBP) and a tetragonal pyramid (TP). The TBP and TP contributions have been quantified based on EPR data. ¹³C and ¹⁵N MAS NMR data show that the Dtc ligands incorporated into the zinc adduct molecule are structurally nonequivalent. The dependence of the isotropic ¹⁵N chemical shifts of the Dtc groups on the alkyl substituents at the nitrogen atom is interpreted based on the concept of joint manifestation of the (+)inductive effect of the alkyl substituents and the mesomeric effect of the Dtc groups.     

Synthesis,crystal structure of a new tetranuclear Ni<Stack><Subscript>2</Subscript><Superscript>II</Superscript></Stack>Cu<Stack><Subscript>2</Subscript><Superscript>II</Superscript></Stack> complex containing a macrocyclic ligand

The first inorg/organic hybrid complex incorporating the macrocyclic oxamide, of formula [(NiL)₂Cu₂(μ-NSC)₂(NSC)₂] (1), (NiL, H₂L = 2, 3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien), have been synthesized and structurally characterized. The crystals crystallize in the triclinic system, space group P-1, for (1) a = 8.319(3) Å, b = 10.434(4) Å, c = 14.166(5) Å, a = 107.030(5)°, β  =  91.257(5)°, γ = 107.623(5)°. The complex involved both bridging N, S-ligand, and oxamide ligand, C–H?S interactions and NCS → Ni weak coordination interactions making the complex superamolecular.     

Synthesis and crystal structure of EnH<Superscript>2</Superscript>[IrCl<Superscript>6</Superscript>]

The preparation of EnH²[IrCl⁶] is described. Crystal data for C₂H₁₀Cl₆IrN₂ are: a = 6.8972(11) Å, b = 6.9435(16) Å, c = 7.3354(11) Å; α = 88.269(3)°, β = 65.495(2)°, γ = 60.305(2)°, V = 270.76(9) ų, space group P1, Z = 1, d_calc = 2.864 g/cm³. Crystal chemical analysis of the general motif of the structure was performed by the translation sublattice identification technique. It has been found that complex anions [IrCl₆]^2? follow the nodes of a rather regular rhombohedral subcell with the parameters a_c = 7.1 Å, α_c = 64°.     

Structural features of acidic fluorophosphatozirconates (hafnates) from the <Superscript>19</Superscript>F, <Superscript>31</Superscript>P, <Superscript>1</Superscript>H NMR data

Fluorophosphatometallates with the composition K₃H₃Zr₃F₃(PO₄)₅, Rb₃H₃Zr₃F₃(PO₄)₅, Rb₃H₃Hf₃F₃(PO₄)₅, CsH₂Hf₂F₂(PO₄)₃?2H₂O are studied by ³¹P, ¹⁹F, and ¹H NMR. It is found that protons enter in the composition of hydrophosphate groups and fluorine atoms occupy the terminal sites in the tetravalent metal environment. Schemes of the crystal structure of fluorophosphatometallates are proposed. It is established that in CsH₂Hf₂F₂(PO₄)₃?2H₂O water molecules are bonded to the phosphate group proton via a strong hydrogen bond and are characterized by a low energy barrier of molecular motions.     

Thermodynamics of citrate complexation with Mn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript> ions

Isothermal titration calorimetry has been used to determine the stoichiometry, formation constants and thermodynamic parameters (ΔG ^o, ΔH, ΔS) for the formation of the citrate complexes with the Mn²⁺, Co²⁺, Ni²⁺ and Zn²⁺ ions. The measurements were run in Cacodylate, Pipes and Mes buffer solutions with a pH of 6, at 298.15 K. A constant ionic strength of 100 mM was maintained with NaClO₄. The influence of a metal ion on its interaction energy with the citrate ions and the stability of the resulting complexes have been discussed.     

Synthesis and X-ray diffraction study of the LaMg<Superscript>I</Superscript>Mg(CrO<Subscript>3</Subscript>)<Subscript>2</Subscript> (M<Superscript>I</Superscript> = Li,Na, K) compounds

Ternary chromites of the composition LaM^IMg(CrO₃)₂ (M^I = Li, Na, K) were synthesized for the first time by ceramic technology from stoichiometric amounts of high purity grade La₂O₃; pure for analysis grade Li₂CO₃, Na₂CO₃, K₂CO₃, and MgCO₃; and chemically pure grade Cr₂O₃. Using X-ray diffractometry, it has been established that compounds are crystallized in cubic and tetragonal crystal systems, and parameters of their crystal lattices have been determined.     

Complex salts with participation of [Rh(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>]<Superscript>3+</Superscript> cations

Four complex salts with the polyatomic [Rh(NH₃)₆]³⁺ cation are synthesized and studied by X-ray diffraction. The crystallographic characteristics of [Rh(NH₃)₆](WO₄)Cl are determined and the structures of [Rh(NH₃)₆]Cl₃, [Rh(NH₃)₆](ReO₄)₃·2H₂O, and [Rh(NH₃)₆](MoO₄)Cl·3H₂O are solved. The features of mutual packing of the fragments are studied.     

Opposite effect of Li<Superscript>+</Superscript> codoping on the upconversion emissions of Er<Superscript>3+</Superscript>-doped TiO<Subscript>2</Subscript> powders

The Er³⁺-Li⁺ codoped TiO₂ powders have been prepared by the non-aqueous sol–gel method. The green and red upconversion emissions centered at about 526, 550 and 663 nm were observed by the ²H_11/2, ⁴S_3/2 → ⁴I_15/2 and ⁴F_9/2 → ⁴I_15/2 transitions of Er³⁺, respectively. Li⁺ codoping has opposite effect on the upconversion emissions intensities for Er³⁺-doped TiO₂ at sintering temperatures of 1,073 and 1,273 K. At 1,073 K, the Er³⁺-doped TiO₂ phase transition from anatase to rutile was accelerated with increasing Li⁺ codoping concentration, leading to the increase of crystal field symmetry of Er³⁺, thus the upconversion emissions intensities decreased. At 1,273 K, Li⁺ codoping had no effect on the phase structure of Er³⁺-doped TiO₂ and only increased the Er–O bond length, it indicated that the upconversion emissions intensities greatly enhanced because of the decrease of crystal field symmetry of Er³⁺.     

Extraction of metal ions (Fe<Superscript>3+</Superscript>, Co<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> and Zn<Superscript>2+</Superscript>) using immobilized-polysiloxane iminobis(n-2-aminophenylacetamide) ligand system

A new insoluble solid functionalized ligand system bearing chelating ligand group of the general formula P-(CH₂)₃-N[CH₂CONH(C₆H₄)NH₂]₂, where P represents [Si–O] _n polysiloxane network, was prepared by the reaction of the immobilized diethyliminodiacetate polysiloxane ligand system, P-(CH₂)₃N(CH₂CO₂Et)₂ with 1,2-diaminobenzene in toluene. ¹³C CP-MAS NMR, XPS and FTIR results showed that most ethylacetate groups (–COOEt) were converted into the amide groups (–N–C=O). The new functionalized ligand system exhibits high capacity for extraction and removal of the metal ions (Fe³⁺, Co²⁺, Ni²⁺, Cu²⁺ and Zn²⁺) with efficiency of 95–97% after recovery from its primary metal complexes. This functionalized ligand system formed 1:1 metal to ligand complexes.     

Specific features of absorption of Cu<Superscript>2+</Superscript>, Zn<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, and Pb<Superscript>2+</Superscript> cations from aqueous solutions by calcium phosphates

Kinetic characteristics of the interaction of trisubstituted calcium phosphate Ca₃(PO₄)₂ · xH₂O with Cu²⁺, Zn²⁺, Co²⁺, and Pb²⁺ ions in aqueous solutions were studied.     

Cation binding by 2<Superscript>1</Superscript>,3<Superscript>1</Superscript>-diphenyl-l <Superscript>2</Superscript>,4<Superscript>2</Superscript>-dioxo-7,10,13-trioxa-1,4(3,1)-diquinoxalina-2 (2,3),3(3,2)-diindolizinacyclopentadecaphane and its acyclic analog

The binding of cations Li⁺, Na⁺, K⁺, Cs⁺, Ag⁺, Zn²⁺, Ni²⁺, Co²⁺, NH₄ ⁺ (group I), H⁺, Mg²⁺, Al³⁺, Ga³⁺ (group II), and Ca²⁺, Pb²⁺ (group III) by 2¹,3¹-diphenyl-l ²,4²-dioxo- 7,10,13-trioxa-l,4(3,1)-diquinoxalina-2(2,3),3(3,2)-diindolizinacyclopentadecaphane (1), which contains two indolizine and two quinoxaline fragments and 3,6,9-trioxaundecanes spacer, and by its acyclic analog (2) was studied using cyclic voltammetry in MeCN/0.1 M Bu₄NBF₄. It was concluded that the ions of group I are not bound by these compounds, the ions of group II exhibit the reversible redox-switched binding by the carbamoyl groups of the quinoxaline fragments, whereas the ions of group III are bound not only by the initial compounds and radical cations 1 and 2, but also by dication 1. This binding of the Ca²⁺ and Pb²⁺ ions stabilizes dication 1.     

Synthesis and Characterization of New Os<Subscript>2</Subscript><Superscript>5+</Superscript> and Os<Subscript>2</Subscript><Superscript>6+</Superscript> Azido Complexes

Reaction of Os₂(OAc)₄Cl₂ with an excess of HDPhF (HDPhF = N,N′-diphenylformamidine) gives a high yield of Os₂(DPhF)₄Cl₂ (1), which can be converted to its azido analog, Os₂(DPhF)₄(N₃)₂ (3), by treatment with NaN₃. We report a major improvement on the preparation of Os₂(chp)₄Cl (2; Hchp = 2-chloro-6-hydroxypyridine) by synthesizing the compound in the reducing solvent ethanol. Reaction of 2 with NaN₃ affords the azido complex Os₂(chp)₄N₃ (4). Compound 3 has been examined by X-ray crystallography, and has an Os–Os bond distance of 2.45 Å, suggesting a (π*)² ground state for the molecule.     

Complex formation of maleic acid with the Zn<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> in aqueous solution

The process of complex formation of maleic acid (H₂L) with the ions Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺ was studied by potentiometric titration in a wide range of concentration ratios at 298 K and I = 0.1 mol/l (NaNO₃). The moieties ZnL, CoL, NiL, NiL ₂ ^2? , CuL, and CuL ₂ ^2? were detected and their stability constants were determined.     

Gasification characteristics to <Superscript>14</Superscript>CO<Subscript>2</Subscript> of <Superscript>14</Superscript>C radionuclide desorbed from spent resin by phosphate solutions

The removal characteristics of H¹⁴CO₃ ⁻ ions from IRN-150 mixed resin contaminated with ¹⁴C radionuclide and the gasification effects of ¹⁴C radionuclide on ¹⁴CO₂ are investigated in this study. The stripping solutions used for the removal of ¹⁴C from spent resin are NaNO₃, Na₃PO₄, NH₄H₂PO₄, and H₃PO₄. The influence of the stripping solution concentration on the desorption characteristics of an inactive HCO₃ ion into a stripping solution from IRN-150 mixed resin and the gasification of this ion to CO₂ is analyzed. The gasification behavior to CO₂ using NaOH, HNO₃, and HCl was also compared to that of phosphate solution. Spent resin stored in Wolsong nuclear power plant is used to evaluate the gasification characteristics of ¹⁴C radionuclide to ¹⁴CO₂. Gamma radionuclides such as ¹³⁷Cs and ⁶⁰Co in residual striping solutions after desorption experiments are analyzed.     

Formation of mononuclear rhodium(III) sulfates: <Superscript>103</Superscript>Rh and <Superscript>17</Superscript>O NMR study

It was shown that the monomeric rhodium sulfate complexes [Rh(H₂O)₄(SO₄)]⁺, trans-[Rh(H₂O)₂(SO₄)₂]^?, cis-[Rh(H₂O)₂(SO₄)₂]^?, and [Rh(SO₄)₃]^3? were not predominant forms in aqueous solutions. The ¹⁰³Rh NMR chemical shifts of the complexes were assigned, and the conditions for their formation in solutions, concentration parameters, and acidity at which the fraction of the monomers was maximal were determined. The constants of formation of the complexes and ion pair (IP) were estimated: K _IP = 8 ± 3.5, K ₁ ≈ 8, K _2trans ≈ 1, K _2cis ≈ 1, and K ₃ ≈ 2.     

Photocatalysis enhancement of CaAl<Subscript>2</Subscript>O<Subscript>4</Subscript>:Eu<Superscript>2+</Superscript>, Nd<Superscript>3+</Superscript>@TiO<Subscript>2</Subscript> composite powders

CaAl₂O₄:Eu²⁺, Nd³⁺@TiO₂ composite powders were synthesized by a sol–gel method under mild conditions (i.e. low temperature and ambient pressure). The as-prepared powders were characterized by transmission electron microscopy (TEM) and analyzed by X-ray diffraction (XRD). The photocatalytic behavior of the TiO₂-base surfaces was evaluated by the degradation of nitrogen monoxide gas. It suggested that CaAl₂O₄:Eu²⁺, Nd³⁺@TiO₂ composite powders were composed of anatase titania and that CaAl₂O₄:Eu²⁺, Nd³⁺. TiO₂ particles were deposited on the surface of CaAl₂O₄:Eu²⁺, Nd³⁺ to form uniform film. CaAl₂O₄:Eu²⁺, Nd³⁺@TiO₂ composite powders exhibited higher photocatalytic activity compared with pure TiO₂ under visible light. And the result also clearly indicated that the long afterglow phosphor absorbed and stored lights for the TiO₂ to remain photocatalytic activity in the dark.     

About the structure of CH<Subscript>5</Subscript><Superscript>+</Superscript> and structural variations in related systems

The carbocation CH₅ ⁺ has a unique structure of C _s symmetry with three 2-center-2-electron bonds and one 3-center-2-electron bond. This ground-state geometry is different from the prediction by the VSEPR model. We have investigated this carbocation along with related systems, among them, BH₅, BLi₅, CLi₅ ⁺, NH₅ ²⁺, NLi₅ ²⁺, to seek possible trends and regularities in the variations of their ground-state geometries.     

Surface properties and structure of organofluorosilicon polymers based on organotrialkoxysilanes R<Superscript>F</Superscript>OCH<Subscript>2</Subscript>Si(OR<Superscript>F</Superscript>)<Subscript>3</Subscript>

The hydrolysis of trifunctional alkoxysilanes R^FOCH₂ Si(OR^F)₃, where R^F = CH₂CF₃, CH₂CF₂CF₃, CH₂CF₂CF₂CF₃, or CH₂CF₂CF₂CF₂CF₃, during the action of atmospheric moisture in the presence of 3-aminopropyltriethoxysilane under mild conditions yields new ladderlike polysiloxanes. Their structure is studied via ¹H NMR spectroscopy, GPC, TGA, and AFM. Polymer coatings prepared on their basis are found to be low-energy and hydrophobic. The total surface energy and polarity of the surface of polysiloxane films decrease, while their hydrophobicity increases with lengthening of the fluoroorganic substituent at the silicon atom.