Viscosities and activation energies of flow of mixtures containing 1,2-dibromoethane

The viscosities of the mixtures of 1,2-dibromoethane + cyclohexane, + benzene, +toluene, +o-xylene, +m-xylene, and +p-xylene have been measured at 298.15 and 308.15 K as a function of composition. The viscosity data have been analysed in the light of approaches developed by Hind and Grunberg . Using Eyring kine- matic scheme the viscosity data have been employed to calculate activation energies of flow.     

Non-bonded interactions in cyclobutane-thiones

Using UVPES and electronic spectral data the presence of an interaction between thd 1,3-thiocarbonyl groups in $\text{2}$ has been identified. EHT calculations also predict such an interaction. Presence of weak interaction between 1,3-carbonyl and thiocarbonyl groups in $\text{3}$ has been inferred from electronic absorption and emission spectra.     

The 1-6 weberite Na2Te2O7 and some observations on compounds with the weberite structure

The 1-6 weberite Na₂Te₂O₇ (Imm2, a = 7.233 Å, b = 10.104 Å, c = 7.454 Å) has been prepared by high-pressure synthesis. It is shown that $\text{a}$) (the mean unit-cell dimension per formula unit) of oxide weberites A₂B₂O₇ can be represented as a linear function of the effective ionic radii of A and B. The problem of the true space-group symmetry of weberite is discussed.     

Studies of molecular motions and vibrational relaxation VII. Rotational diffusion model to investigate the band shapes of the ν5 and ν8 ban

Reorientational correlation functions G_rot^(l)(t)) for the degenerate (E) bands of liquid acetonitrile (CH₃CN) have been computed us NMR spin-lattice relaxation data (for CD₃CN) and gas phase Raman band profiles, assuming that the rotational diffusion model is valid. The effects both anisotropic rotational motion and of Coriolis coupling are included. The predicted correlation functions along with those calculated using ther cl “free” rotor equations, have been compared with those obtained from the υ_s (Raman) and υ_s (IR and Raman) experimental band profiles. It shown that, despite the simplicity of the model and obvious (understandable) discrepancies at short times, sensible conclusions may be drawn. This work a starting point for the testing of more complicated models for reorientational motion in dense phases.     

Programmed probe thermal analysis and its use in the study of thermal decomposition of some trans-substituted derivatives of zeise's salt

A mass spectrometer equipped with a programmed probe and a total ion monitor may be used to study thermal decompositions by gradually heating the sample in the probe. The ion current is monitored and mass spectra taken at appropriate points permit the identification of decomposition products. Single ion monitoring can also be employed. The method has been used to examine a series of compounds formed by the replacement of the trans-Cl ligand of Zeise's salt. Pathways for the thermal decomposition are postulated.     

The mechanism of the photoinduced hydrogenation of norbornadiene catalyzed by chromium carbonyl complexes

Kinetic, spectrophotometric and actinometric investigations of the hydrogenation of norbornadiene catalyzed by norbornadiene—Cr(CO)₄ show that the photoinduced transients promote thermal catalytic cycles.     

Electrochemical reduction of 4-thienylquinazoline in dimethylformamide

Electrochemical reduction of 4-thienylquinazoline (4-TQ) at the dropping mercury electrode in dimethylformamide solutions containing 0.1 M tetrabutyl ammonium iodide supporting electrolyte gave two well-defined diffusion-controlled waves. The first wave was found to be quasi-reversible and the second irreversible, on the basis of the usual criteria. The controlled potential electrolysis experiments carried out at the limiting regions of the frist and the total waves of 4-TQ yielded the same number of electrons, namely two, in both cases. Mechanisms corresponding to the total wave and the first wave were proposed based on the results obtained.     

Origin of the quadrupole splitting in the Mössbauer 57Fe spectrum of cubic (disordered) LiFeO2

The room-temperature Mössbauer ⁵⁷Fe spectrum of polycrystalline disordered cubic α-LiFeO₂ contains a quadrupole splitting |Δ_obs| of 0.65(2) mm/sec. This value is relatively large for an Fe atom in an essentially Fe³⁺_HS state. To account for its magnitude, the distribution of the electric-field gradient (EFG) values associated with the Fe atoms was investigated by means of exact geometric analysis involving the 12 nearest cation neighbors (model A) as well as large-scale computer simulation involving more distant cations (models B to E). It is found that (1) the major contribution to |Δ_obs| comes from the distribution of +1 and +3 charges among the 12 nearest cation neighbors of a reference Fe atom; (2) this contribution by itself largely accounts for |Δ_obs|; (3) the contribution from cations beyond the seventh-nearest neighbors is marginal; (4) displacing the oxygen atoms from their lattice sites toward adjacent Fe atoms produces a significant effect on the distribution of EFG values at a reference Fe atom, while incipient cation ordering appears to have a relatively small effect; and (5) the contribution of the EFG = 0 component to model |EFG| distributions will be overemphasized unless cations beyond the first-nearest neighbors are included in the EFG summation. The 144 distinct (up to rotation and reflection) Li¹⁺_12?kFe³⁺_k configurations on the coordination cuboctahedron of nearest cation neighbors (required for the examination of model A) are listed, together with their symmetries and multiplicities, and it is shown that the 144 configurations engender only 17 distinct |EFG| values. Observations are also made on various geometric aspects of calculating EFG at ⁵⁷Fe³⁺_HS on cubic lattices.     

Synthese und struktur von dicyclopentadienyl(trimethylsilyl)titanchlorid

Dicyclopentadienyl(trimethylsilyl)titanium chloride, a stable trimethylsilyltitanium compound, is synthesized by reaction of dicyclopentadienyltitanium dichloride and tris(trimethylsilyl)aluminium, coordinated with diethyl ether, or lithium tetarakis(trimethylsilyl)aluminate. The IR and NMR spectra are reported. The crystal structure of the title compound has been determined. It shows a distorted tetrahedral surrounding of the titanium atom; the Ti–Si distance is 267 pm.     

Etudes stereochimiques dans la serie du silacyclopentane: synthese de dimethyl-1,2 alcoxy-1 silacyclopentanes a stereoisomere preferentiel

The stereoselective alcoholysis of 1,2-dimethyl-1-chlorosilacyclopentane and the catalytic alcoholysis of 1,2-dimethylsilacyclopentane are described.     

Application of a new catalyst based on molybdenum for the direct determination of oxygen by pyrolytic gas chromatography

Application of a new catalyst for the direct determination of oxygen by using a pyrolytic gas chromatographic technique is described. Achievement of the optimum experimental conditions depends upon numerous factors which have been examined. The results obtained with such a procedure indicate that the method is applicable for the determination of oxygen in a variety of organic and organometallic compounds.     

Interaction of cyclopentane with benzene,carbon tetrachloride and cyclohexane

Heats of mixing cyclopentane + benzene, + carbon tetrachloride, + cyclohexane at 308.15 K and for cyclohexane + carbon tetrachloride at 298.15 K have been determined in an adiabatic calorimeter. The data have been examined for current theories (McGlashan, Flory and Barker) of solutions and show that McGlashan's theory predicts values for H^E and G^E that are in good agreement with their corresponding experimental values. Interaction energy between the components of these mixtures has also been determined.     

Energy transfer between Eu2+ ions in RbMgF3 crystals

Time-resolved spectroscopy after pulsed nitrogen laser excitation was used to characterize the energy transfer between Eu²⁺ ions in different crystal field sites in RbMgF₃ crystals. The results are consistent with electric dipole—dipole interaction and indicate that the Eu²⁺ ions are forming clusters in this host. As temperature is raised, the upper crystal field components of the metastable states of the ions become thermally populated and this changes the characteristics of the transfer process.     

Thermogenese: Application des filtrages electronique et numerique inverses en calorimetre a conduction

The results of the application of the numerical and electronic inverse filtering to the same calorimetric output are presented. These two techniques, used to reduce the inertia of conduction calorimeters, give very similar results.     

Interaction of chloroform with aniline, o-toluidine and N,N-dimethyl aniline

Heats of mixing aniline, o-toluidine, and N,N-dimethyl aniline with chloroform have been determined by an adiabatic calorimeter. The results have been examined for molecular interactions between them, and they indicate that aniline and o-toluidine are associated through hydrogen bonds. Enthalpy of bond formation in a 1:1 complex has also been determined.     

Diels-Alder reaction of furan with some dienophiles

The reaction of furan and maleic acid was carried out in several solvents. The endo-adduct was isolated and the structure established by its spectral properties and conversion into known compounds. The adducts of furan with fumaric acid, diethyl fumarate and diethyl maleate are reported.