Structural Inhomogeneity in Electrolyte Solutions: The Calcium Perchlorate–Water System

A new approach has been proposed to study the structure of aqueous electrolyte solutions. NIR, Raman and attenuated total reflectance, Fourier transform infra-red (ATR FTIR) spectra have been measured for aqueous calcium perchlorate solutions in the 0.22–4.3 mol·L^?1 (0.22–7.46 mol·kg^?1) concentration range at 25 °C. By the methods of principal component analysis (PCA) and multivariate curve resolution—alternating least squares (MCR-ALS) the number, spectra and concentration profiles have been determined for spectroscopically distinguishable forms of water and ClO ₄ ^? ion in solutions. The results have been analyzed using a phenomenological model, establishing thereby: concentration ranges for structural rearrangements of the solution, the nature of structural microirregularities and different states of the ClO ₄ ^? ion in the areas of domination of the natural water structure, and of cybotactic groups of calcium perchlorate hexa and tetra hydrates.     

Rate constant of the recombination of CF<Stack><Subscript>3</Subscript><Superscript>•</Superscript></Stack> radicals in a gas (He,Ar, N<Subscript>2</Subscript>, or CF<Subscript>3</Subscript>I)

From recent rate constant data for the recombination reaction 2CF₃^• → C₂F₆ ($ k_{(CF_3 )_2 }^M $ k_{(CF_3 )_2 }^M ) in the high-pressure limit and from experimental data obtained at intermediate pressures of buffer gases M (M = He, Ar, N₂, CF₃I), analytical expressions for $ k_{(CF_3 )_2 }^M $ k_{(CF_3 )_2 }^M (in Lindemann’s formulation) are derived for the temperature range of 300–1300 K and intermediate pressures of the buffer gases.     

Isothermal pyrolysis of iodomethanes in gases

The fact was established that the pyrolysis of gaseous iodomethanes RI yields methane and non traces of recombination products R2. A pyrolysis mechanism was proposed and rate constants of limiting stages of the pyrolysis of iodomethane, trideuteroiodomethane, and diiodomethane over the range of 500–1500 K were determined.     

Rearrangement of the Binuclear K4Mo2Cl8 Cluster Structure in the Process of Its Oxidation in HCl Solution

Russian Journal of General Chemistry - Batch-type spectroscopic and continuous potentiometric titration of K4Mo2Cl8 with potassium dichromate in 1 M hydrochloric acid was carried out. Intermediate...     

New Mechanism of Photodissociation of Gaseous Acetone

It is found for the first time that photolysis of gaseous acetone under UV irradiation produces ethane not only via recombination of methyl radicals, but also by the mechanism of induced predissociation.     

On inhibition of calcium sulfate crystallization with phosphonic complexes

IR spectra of propylene glycol solutions in water were measured in the region of the first overtone of water. The inhibition efficiency of calcium sulfate was determined as a function of the pH value and propylene glycol content of water. A concept is suggested for taking into account the water-complexone interaction in inhibition of calcium sulfate crystallization with phosphonic acids.     

Isotope Effects and Final Products in Pyrolysis of Halomethanes and Perfluoroalkyl Iodides

Final products of isothermal pyrolysis of CF₂HBr, CF₂ClBr, CH₃I, CH₂I₂, CHI₃, i-C₃F₇I, and C₄F₉I were determined and mechanisms of their formation were proposed. The enthalpy of formation of the free biradical CFBr^·· (Δ_fH ₀ ⁰ = 80±20, Δ _fH ₀ ²⁹⁸ = 60±20 kJ mol^?1) was estimated. The dissociation energies E_{D, 0}(ID₂C-D), E_D,298(ID₂C-D), and E_D,0(IH₂C-D) equal to 437±6, 444±6, and 435±4 kJ mol^?1, respectively, were determined.     

Reactions of 2,4-hexadiyne-1,6-diol with [H2Os3(CO)9(PR3)] clusters. Cyclization of the diyne and reversible exchange of the phosphine ligands between different positions of the "Os3C3" framework

Reactions between unsaturated [H(2)Os(3)(CO)(9)(PR(3))] clusters (PR(3)= PPh(3), P(4-CF(3)-C(6)H(4))(3), PEt(3)) and 2,4-hexadiyne-1,6-diol have been studied. It was found that the diyne ligand easily reacts with all these complexes to give [HOs(3)(CO)8(PR3)-[mu3, eta1:eta3:eta1)-(CH(3)-C-C=CH-CH=C-O)]] complexes (V, VI and VII, respectively) containing the "Os3C3" pentagonal pyramid cluster framework. This structural pattern is formed through the diyne cyclization, dissociation of a CO ligand and eventual coordination of the cyclized organic moiety to the osmium triangle in the [mu3, eta1:eta3:eta1) manner. In the case of the PEt(3) substituted cluster the second hydride transfer onto the organic fragment occurs to afford the nonhydride [Os(3)(CO)(8)(PR3)[mu3), eta1:eta2:eta1)-(CH(3)-CH-C=CH-CH=C-O)]] cluster, VIII, containing distorted pentagonal pyramid framework with a broken Os-C bond. Heating V, VI of VII and in hexane solutions results in formation of the regioisomers (Va, VIa and VIIa) with the phosphine ligand located at adjacent osmium atoms across the Os-Os bond bridged by the coordinated organic fragment. The most probable mechanism of the isomerization includes reversible phosphine migration between these metal centres. Solid-state structure of V, Va, VI, VIIa and VIII have been established by single crystal X-ray diffraction. A general mechanistic scheme for the diyne ligand cyclization and cluster framework transformations is suggested and discussed.