Theoretical investigation on the kinetics and thermochemisty of H-atom abstraction reactions of 2-chloroethyl methyl ether (CH<Subscript>3</Subscript>OCH<Subscript>2</Subscript>CH<Subscript>2</Subscript>Cl) with OH radical at 298 K

Kinetics and thermochemistry of the H-atom abstraction reaction of CH₃OCH₂CH₂Cl with OH radical have been carried out using dual level of methods. Initially, geometry optimization and frequency calculations are performed at M06-2X/6-31+G(d, p) level of theory, and energetic calculations are further refined using CCSD(T)/6-311++G(d, p) level of theory in order to characterized all stationary points on potential energy surface (PES). The result shows that H-atom abstraction from –OCH₂ site of CH₃OCH₂CH₂Cl is dominant path. The rate constants are calculated using canonical transition state theory at 298 K, which are found to be in good agreement with the experimental data. We have presented the standard enthalpies of formation for CH₃OCH₂CH₂Cl and the radicals generated during the H-atom abstraction using group-balanced isodesmic reactions scheme. The atmospheric lifetime of title molecule is also calculated.     

Osmium(IV) thiocarbamide complexes. Synthesis and crystal and molecular structures of [Os(Thio)<Subscript>2</Subscript>Cl<Subscript>4</Subscript>] · 2H<Subscript>2</Subscript>O

Tetrachlorobis(thiocarbamide)osmium(IV) dehydrate, [Os(Thio)₂Cl₄] · 2H₂O, was synthesized by the reaction of K₂[OsO₂(OH)₄] with thiocarbamide in 6 M HCl. The compound was characterized by chemical analysis and IR, UV, and X-ray photoelectron spectroscopies. The structure was determined by X-ray diffraction analysis. The coordination polyhedron of the osmium atom lying in the axis 2 is a distorted cis-octahedron formed by four chlorine atoms and two sulfur atoms of two monodentate thiocarbamide ligands: Os-S 2.3075(18) Å and Os-Cl 2.3625(18) Å (trans to Cl) and 2.4294(19) Å (trans to S). The conditions for the formation of the osmium(IV) thiocarbamide complexes in HCl solutions were determined using spectrophotometry, and the spectral characteristics of [Os(Thio)Cl₅]^? were obtained.     

Ternary Systems NaHal–NaVO<Subscript>3</Subscript>–Na<Subscript>2</Subscript>CrO<Subscript>4</Subscript> (Hal = Cl,Br)

Phase equilibria in the ternary systems NaHal–NaVO₃–Na₂CrO₄ (Hal = Cl, Br) were studied. By differential thermal analysis, eutectic alloys were found at points with coordinates (14.0 mol % NaCl, 66.5 mol % NaVO3, 19.5 mol % Na₂CrO₄, 530°C) and (27.0 mol % NaBr, 47.5 mol % NaVO₃, 25.5 mol % Na₂CrO₄, 499°C). By differential scanning calorimetry, the specific enthalpies of melting of the eutectics were determined. X-ray powder diffraction analysis of the eutectic alloy in the system NaBr–NaVO₃–Na₂CrO₄ was made.     

Clathrate [Zn(C<Subscript>6</Subscript>H<Subscript>5</Subscript>COO)<Subscript>2</Subscript>(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>] · 2CH<Subscript>3</Subscript>COOH: Synthesis and crystal structure

The clathrate [Zn(C₆H₅COO)₂(H₂O)₂] · 2CH₃COOH (I) was obtained for the first time from zinc(II) benzoate. The individuality, the unit cell parameters, and the number of “guest” molecules in complex I were determined from X-ray diffraction and derivatographic data. Its crystal structure was solved.     

Physicochemical properties of (CH<Subscript>3</Subscript>)<Subscript>2</Subscript>NH<Subscript>2</Subscript>Cl–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> composites

Composite solid electrolytes were synthesized from the organic salt dimethylammonium chloride (1–x)C₂H₈NCl–xAl₂O₃. Their physicochemical properties were studied. In the starting C₂H₈NCl salt, there is a phase transition at 39°C accompanied by an increase in conductivity by two orders of magnitude. The conductivity of the high-temperature phase is 9.3 × 10^–6 S/cm at 160°C. A differential scanning calorimetry study showed that the salt in the composites spreads over the oxide surface and at x > 0.6 the salt melting enthalpy decreases to zero. The conductivity of the resulting composites was studied by impedance spectroscopy. It was shown that heterogeneous doping leads to a sharp increase in ion conductivity to 7.0 × 10^–3 S/cm at 160°C and a decrease in the activation energy to 0.55 eV.     

Synthesis and thermal properties of Co<Subscript>2</Subscript>P<Subscript>2</Subscript>O<Subscript>7</Subscript> · 6H<Subscript>2</Subscript>O

The dependence of solid phase composition on the main parameters of the interaction in the CoSO₄-K₄P₂O₇-H₂O system was studied. The synthesis conditions were determined and a crystalline cobalt(II) diphosphat of the composition Co₂P₂O₇ · 6H₂O was synthesized. Its thermal properties were studied. The composition and the intervals, wherein the thermally stable products of partial and complete dehydration of Co₂P₂O₇ · 6H₂O are formed, were specified. The final heat treatment product, anhydrous α-Co₂P₂O₇, was identified and a sequence of the solid phase thermal transformations accompanying its formation was established.     

Theoretical study for the CH<Subscript>3</Subscript>OCF<Subscript>2</Subscript>CF<Subscript>2</Subscript>OCHO + Cl reaction

The reaction of CH₃OCF₂CF₂OCHO with Cl atom has been investigated theoretically by direct dynamics method. The BB1K hybrid functional in conjunction with the 6-31 + G(d,p) basis set has been used to optimize the geometries for the stationary points and explore the potential energy surface of the reaction. Four rotation conformers (RC1-4) of CH₃OCF₂CF₂OCHO are identified, and they are all considered in the kinetic calculation. For each conformer, there are two kinds of H-abstraction channels and one displacement channel, and the latter one should be negligible due to involving much higher energy barrier than the former two. The individual rate constants for each H-abstraction channel are evaluated by the improved canonical variational transition-state theory with a small-curvature tunneling correction. The overall rate constant is evaluated by the Boltzmann distribution function, and a fitted four-parameter rate constant expression is obtained over a wide temperature range of 200–2,000 K. The agreement between the calculated and available experimental value at 296 K is good. The contribution of each conformer to the title reaction is discussed with respect to the temperature. In addition, because of the lack of available experimental data for the species involved in the reactions, the enthalpies of the formation (ΔH _f,298°) for the reactant and its product radicals are predicted via isodesmic reaction at the BB1K/6-31 + G(d,p) level.     

Synthesis and physicochemical study of M<Subscript>4</Subscript>Na<Subscript>2</Subscript>V<Subscript>10</Subscript>O<Subscript>28</Subscript> · 10H<Subscript>2</Subscript>O (M=K,Rb, NH<Subscript>4</Subscript>)

The formation conditions and physicochemical properties of binary decavanadates M₄Na₂V₁₀O₂₈ · 10H₂O (M=K, Rb, NH₄), synthesized by crystallization from saturated solutions of the NaVO₃-MH₂AsO₄-H₂O systems, were studied by chemical analysis, X-ray powder diffraction, microscopy, thermogravimetry, and IR spectroscopy. To optimize the synthesis conditions of M₄Na₂V₁₀O₂₈ · 10H₂O, the ( 1-x)NaVO₃ · 2H₂O · xMH2AsO4-H₂O (0.2 ≤ x ≤ 0.8) isomolar series method was applied to studying the interaction in the NaVO₃-MH₂AsO₄-H₂O systems (M = K, Rb, Cs) at the 0.4 mol/L total molar concentration of NaVO₃ and MH₂AsO₄ in solutions. The studied M₄Na₂V₁₀O₂₈ · 10H₂O compounds were shown to be isostructural with triclinic crystals (Z= 1, space group P $ \bar 1 $ \bar 1 ), and their unit cell parameters were estimated.     

A theoretical investigation on the structures and stabilities of C<Subscript>60</Subscript>X<Subscript>18</Subscript> and C<Subscript>70</Subscript>X<Subscript>10</Subscript> (X = H,F, Cl,and Br)

A density functional theory study was performed on fullerene derivatives C₆₀X₁₈ and C₇₀X₁₀ (X = H, F, Cl, and Br). The calculated results show that the lowest energy isomers are IPR-satisfying for C₆₀X₁₈ (X = H, F, Cl, and Br). It is found that the addition patterns of X (X = Cl and Br) are different from those of X (X = H and F) for C₆₀, demonstrating that the stability of fullerene derivatives is partly attributed to the steric repulsion and electronegativity of added atoms. However, the lowest energy isomers are IPR-violating for C₇₀X₁₀ (X = H, F, and Cl), suggesting that many more fullerene derivatives may violate the isolated pentagon rule.     

A Raman Spectroscopic Study of Aqueous La(CH<Subscript>3</Subscript>CO<Subscript>2</Subscript>)<Subscript>3</Subscript> Solutions and La(CH<Subscript>3</Subscript>CO<Subscript>2</Subscript>)<Subscript>3</Subscript>·1.5 H<Subscript>2</Subscript>O(cr)

Aqueous solutions of La(CH₃CO₂)₃, NaCH₃CO₂ and La(ClO₄)₃ were studied using Raman spectroscopy. In dilute NaCH₃CO₂ solution, acetate is fully hydrated and forms only minor amounts of ion pairs. The characteristic Raman bands are discussed and assigned. In fairly dilute La(ClO₄)₃ solutions, the La³⁺(aq) ion occurs as the nonahydrate. The separation of the carboxylate bands, ν_as – ν_s (Δ-value), in NaCH₃CO₂(cr) compared to La(CH₃CO₂)₃·1.5H₂O(cr) correlates with the bonding type of acetate which is “ionic” in the former but bidentate chelating/tridentate chelating in the latter. Other acetate bands such as the deformation mode of the CO₂ moiety, δ CO₂, and the two rocking vibrations (ρ), as well as the C–C stretch show marked differences in their band positions in NaCH₃CO₂(cr) compared to the ones in La(CH₃CO₂)₃·1.5H₂O(aq). In a ternary solution of La(CH₃CO₂)₃/LaCl₃ with a molar ratio La³⁺(aq): \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \)(aq) = 3.87: 1.00), the bands of the bound acetate on La³⁺ were characterized and compared to those of fully hydrated acetate, \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \left( {\text{aq}} \right) \). In this solution, almost all acetate is ligated to La³⁺ in a bidentate fashion and two complex species could be identified (molar ratios La³⁺: \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \)  = 1:1 and 1:2, respectively). In La(CH₃CO₂)₃ solutions in H₂O and D₂O strong acetato complexes are formed and the bands of the bound acetate were characterized and compared with the ones of the fully hydrated acetate modes. A dilution series down to 0.0037 mol·L^?1 in La(CH₃CO₂)₃(aq) and to 0.0150 mol·L^?1 in La(CH₃CO₂)₃(D₂O) showed that two acetate complexes are formed in these solutions. Again, it was shown that in these solutions the bound acetates on La³⁺ exist as bidentate ligands. DFT frequencies of the acetate on clusters {La(OH₂)₇O₂CCH₃)}²⁺ and {La(OH₂)₅(O₂CCH₃)₂}⁺ compared well with the measured values. By determining the ligation number, \( \bar{n} \), it can be established that in dilute solutions, below 0.04 mol·L^?1, a complex with a 1:1 stoichiometry (La³⁺: \( {\text{CH}}_{3} {\text{CO}}_{2}^{ - } \)) exists in equilibrium with “free” acetate while in more concentrated solutions a 1:2 complex also forms. La³⁺(aq) hydrolysis is slight and very small equilibrium concentrations of CH₃COOH were detected (C–C stretch at 893 cm^?1). From quantitative Raman measurements, K ₁ was determined to be 160 ± 10 at 22 °C.     

Synthesis and photocatalytic activity of mesoporous SiO<Subscript>2</Subscript>–TiO<Subscript>2</Subscript>

Mesoporous SiO₂–TiO₂ was synthesized by the sol–gel method using Si(OC₂H₅)₄, Ti(OC₂H₅)₄, and stearyltrimethylammonium chloride. By using acetylacetone as the capping agent of Ti(OC₂H₅)₄, homogeneous SiO₂–TiO₂ composite was obtained. Spherical mesoporous SiO₂–TiO₂ was also synthesized by the sol–gel method using W/O emulsion under microwave irradiation. The specific surface area of these mesoporous SiO₂–TiO₂ materials decreased when the Ti/Si molar ratio was higher than 0.1, which indicated that Ti was homogeneously distributed in mesoporous SiO₂ matrix at Ti/Si ≦ 0.1. The photocatalytic activity of mesoporous SiO₂–TiO₂ materials was investigated by the degradation of methylene-blue in water under UV light irradiation. Mesoporous SiO₂–TiO₂ was effective for the adsorption–decomposition of methylene-blue.     

Synthesis and structure of M[UO<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)(NCS)] · 0.5H<Subscript>2</Subscript>O (M = Rb or Cs)

Single crystals of M[UO₂(C₂O₄)(NCS)] · 0.5H₂O (M = Rb (I) or Cs (II)) have been synthesized and studied by X-ray diffraction analysis. The compounds are isostructural, and their crystals are monoclinic with the space group C2/c, Z = 4, and unit cell parameters: a = 9.0624(5) Å, b = 13.1242(7) Å, c = 8.9204(5) Å, β = 98.897(2)°, R = 0.0226 (I); a = 9.3171(3) Å, b = 13.2987(5) Å, c = 9.1151(3) Å, β = 101.0860(10)°, R = 0.0214 (II). The main structural units of the crystals of I and II are the [[UO₂(C₂O₄)(NCS)]^? chains belonging to the crystal-chemical group AK⁰²M¹ (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , M¹ = NCS^? of the uranyl complexes. The uranium-containing chains are joined into a three-dimensional framework through electrostatic interactions with the outer-sphere cations and hydrogen bonds involving the water molecules.     

Synthesis and heat capacity study of stannates Dy<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript> and Ho<Subscript>2</Subscript>Sn<Subscript>2</Subscript>O<Subscript>7</Subscript> in the range 370–1000 K

Stannates Dy₂Sn₂O₇ and Ho₂Sn₂O₇ are produced by solid-phase synthesis from Dy₂O₃ (Ho₂O₃)–SnO₂ stoichiometric mixtures by calcining at 1473 K. The molar heat capacity of holmium and dysprosium stannates is measured by differential scanning calorimetry (DSC) in the temperature range 370–1000 K. The experimental data are used to calculate thermodynamic properties (enthalpy change H°(T)–H°(370 K), entropy change S°(T)–S°(370 K), and the reduced Gibbs free energy Φ°(T)) of the synthesized compound.     

Synthesis,Structure and Solid-Phase Transformations of Fe Nitrosyl Complex Na<Subscript>2</Subscript>[Fe<Subscript>2</Subscript>(S<Subscript>2</Subscript>O<Subscript>3</Subscript>)<Subscript>2</Subscript>(NO)<Subscript>4</Subscript>] · 4H<Subscript>2</Subscript>O

Binuclear iron nitrosyl complex Na₂[Fe₂(S₂O₃)₂(NO)₄] · 4H₂O (I) was synthesized by the reaction of iron(II) sulfate with sodium thiosulfate in the flow of NO gas. According to X-ray diffraction data, the [Fe₂(S₂O₃)₂(NO)₄]^2– anion has binuclear centrosymmetric structure with Fe atoms bonded by the µ-S atoms of thiosulfate groups. The isomeric shift for complex I =0.168(1) mm/s and quadrupole splitting E _Q =1.288 mm/s at T=80 K. When heated, complex I transforms to Na₂[Fe₂(S₂O₃)₂(NO)₄] (II), whose unit cell parameters found by X-ray diffraction method differ from those of complex I. The process of transformation of I to II was studied by calorimetric method. Complex I transforms to complex II without chemical decomposition, which was confirmed by IR and mass spectroscopy data.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 5, 2005, pp. 323–328.Original Russian Text Copyright © 2005 by Sanina, Aldoshin, Rudneva, Golovina, Shilov, Shulga, Martynenko, Ovanesyan.     

Synthesis and crystal structures of [K(H<Subscript>2</Subscript>O)(Piv)]<Subscript>∞</Subscript> and [K<Subscript>2</Subscript>(Phen)(H<Subscript>2</Subscript>O)<Subscript>2</Subscript>(Piv)<Subscript>2</Subscript>]<Subscript>∞</Subscript>

A method for the synthesis of potassium pivalates (trimethylacetates) from potassium tert-butoxide and pivalic acid was proposed. The complexes of the formulas [K(H₂O)(Piv)]_∞(I) and [K₂(Phen)(H₂O)₂(Piv)₂]_∞ (II) (Piv denotes the pivalate anion and Phen denotes 1,10-phenanthroline) were obtained and characterized by elemental analysis and IR and ¹H NMR spectroscopy. The crystal structures of complexes I and II were determined using X-ray diffraction. Crystal structure I has a layered motif with two nonequivalent K atoms (C.N.s 5 + 2 and 6). The coordination of phenanthroline in II gives rise to a ribbon motif, the structure containing three nonequivalent K atoms (C.N.s 6, 6 + 1, and 8).     

Synthesis and structure of antimony compounds (Ph<Subscript>3</Subscript>SbBr)<Subscript>2</Subscript>O · 2PhH and [(2-MeC<Subscript>6</Subscript>H<Subscript>4</Subscript>)<Subscript>3</Subscript>SbBr]<Subscript>2</Subscript>O · 0.5PhH

Hydrolysis of triphenylantimony dibromide or tri(o-tolyl)antimony dibromide in benzene yields the solvates (Ph₃SbBr)₂O · 2PhH (triclinic modification) (I) and [(2-MeC₆H₄)₃SbBr]₂O · 0.5PhH (II), in which the Sb atoms have a distorted trigonal-bipyramidal coordination. The aryl ligands are in the equatorial positions; the bridging oxygen atom and the terminal Br ligands occupy the axial positions. The bond lengths in I: Sb-C, 2.103(2)–2.125(2) Å, Sb-O, 1.976(1) and 1.979(1); and Sb-Br, 2.7128(2) and 2.7592(2) Å. The bond lengths in II (Å): Sb-C, 2.109(6)–2.145(3) Å; Sb-O, 1.954(4)–1.958(4) Å; and Sb-Br, 2.7355(8)–2.7624(7) Å. The angles SbOSb are equal to 138.83(6)° in I and 170.8(3)° and 161.6° in II.     

New double complex salt [PdEn<Subscript>2</Subscript>]<Subscript>3</Subscript>[Rh(NO<Subscript>2</Subscript>)<Subscript>6</Subscript>]<Subscript>2</Subscript> · 2.67H<Subscript>2</Subscript>O: Synthesis,crystal structure,and thermal properties

The crystal structure of the double complex salt (DCS) [PdEn₂]₃[Rh(NO₂)₆]₂ ? 2.67H₂O (I) has been determined by X-ray diffraction. Crystals are triclinic, space group \(P\bar 1\), Z = 4, a = 9.2331(3) Å, b = 9.9136(4) Å, c = 13.7824(5) Å, α = 84.3230(14)°, β = 89.9655(14)°, γ = 66.7272(13)°, V = 1152.19(7) ų, ρ_calcd = 2.141 g/cm³, R = 0.0279. The thermal behavior of complex salt I has been studied in various gas atmospheres. The end product of thermolysis in reductive atmosphere is a mixture of Pd_0.45Rh_0.55 and Pd_0.95Rh_0.05 solid solutions. The end product of thermolysis in an inert atmosphere is a homogeneous Pd_0.6Rh_0.4 solid solution.     

Composition and structure of hydrates of CH<Subscript>3</Subscript>COOH molecules and CH<Subscript>3</Subscript>CO<Subscript>2</Subscript><Superscript>−</Superscript> anions in aqueous solutions

The optimal configurations, energy parameters, and normal vibrational frequencies of hydrates of the acetic acid molecule and anion (CH₃COOH·(H₂O) _n (n = 1-10) and CH₃CO₂^??(H₂O) _n (n = 1-8, 16)) are calculated by density functional theory (B3LYP/6-31++G(_d,_p)). The comparison of the calculation results with the known experimental data (Raman, NMR, and so on) gives arguments in favor of the existence of two stable heteroassociates (HAs) in СН₃СООН–H₂O solutions: previously found CH₃COOH·(H₂O)₂ heterotrimer and CH₃COOH·(H₂O)₈, and three complexes (CH₃CO₂^??(H₂O)₂, CH₃CO₂^??(H₂O)₆, and CH₃CO₂^??(H₂O)₁₆) in NaCH₃CO₂^?–H₂O solutions. Each of them is most stable in a series of isomers, contains unstrained H bonds, and is characterized by the maximum molecular packing density among HAs with similar n values. The structure of the subsequent complex formed in solution uniquely follows the structure of the preceding complex and is based on it.     

Synthesis and thermal analysis of indium-based hydrotalcites of formula Mg<Subscript>6</Subscript>In<Subscript>2</Subscript>(CO<Subscript>3</Subscript>)(OH)<Subscript>16</Subscript>·4H<Subscript>2</Subscript>O

Insight into the unique structure of layered double hydroxides (LDHs) has been obtained using a combination of X-ray diffraction and thermal analysis. Indium containing hydrotalcites of formula Mg₄In₂(CO₃)(OH)₁₂·4H₂O (2:1 In-LDH) through to Mg₈In₂(CO₃)(OH)₁₈·4H₂O (4:1 In-LDH) with variation in the Mg:In ratio have been successfully synthesised. The d(003) spacing varied from 7.83 Å for the 2:1 LDH to 8.15 Å for the 3:1 indium containing LDH. Distinct mass loss steps attributed to dehydration, dehydroxylation and decarbonation are observed for the indium containing hydrotalcite. Dehydration occurs over the temperature range ambient to 205 °C. Dehydroxylation takes place in a series of steps over the 238–277 °C temperature range. Decarbonation occurs between 763 and 795 °C. The dehydroxylation and decarbonation steps depend upon the Mg:In ratio. The formation of indium containing hydrotalcites and their thermal activation provides a method for the synthesis of indium oxide-based catalysts.     

Synthesis and crystal structure of [Cr(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl][PdCl<Subscript>4</Subscript>]·H<Subscript>2</Subscript>O

Synthesis and investigation of a binary complex salt [Cr(NH₃)₅Cl][PdCl₄]·H₂O is reported. The compound is isostructural with [Rh(NH₃)₅Cl][PdCl₄]·H₂O studied earlier; it was characterized by element analysis and powder and single crystal X-ray diffraction. Crystal data for H₁₇Cl₅N₅OPdCr: a = 7.8668(12) Å, b = 10.9703(16) Å, c = 16.048(2) Å, = 102.469(3)°, space group P2₁/c, Z = 4, V = 1352.3(3)ų, d _calc = 2.155 g/cm³.Original Russian Text Copyright © 2004 by I. A. Baidina, P. E. Plyusnin, S. V. Korenev, K. V. Yusenko, Yu. V. Shubin, and S. A. GromilovTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 549–552, May–June 2004.