[en] The modern concepts on specific features of anisotropy of the electron density of valence shells of bound atoms and chemical bonds providing the successful description of the properties of halogen bonds formed by the iodine molecule in compounds with useful physicochemical properties are generalized in the review. The prognoses of basicity by the diiodine basicity scale for the nitrogen-containing compounds are illustrated. The regularities and peculiarities of shifting bands in Raman spectra of iodine-containing organic crystals are considered. The methodical and specific problems of modeling appeared when the electronic characteristics of the iodine compounds are estimated and briefly discussed.

[en] Optimally shaped femtosecond laser pulses can often be effectively identified in adaptive feedback quantum control experiments, but elucidating the underlying control mechanism can be a difficult task requiring significant additional analysis. We introduce landscape Hessian analysis (LHA) as a practical experimental tool to aid in elucidating control mechanism insights. This technique is applied to the dissociative ionization of CH₂BrI using shaped fs laser pulses for optimization of the absolute yields of ionic fragments as well as their ratios for the competing processes of breaking the C–Br and C–I bonds. The experimental results suggest that these nominally complex problems can be reduced to a low-dimensional control space with insights into the control mechanisms. While the optimal yield for some fragments is dominated by a non-resonant intensity-driven process, the optimal generation of other fragments maa difficult task requiring significant additionaly be explained by a non-resonant process coupled to few level resonant dynamics. Theoretical analysis and modeling is consistent with the experimental observations. (paper)

[en] Photodissociation dynamics of organic halides has been extensively investigated due to its potential to the stratosphere ozone depletion and relevant environmental problems. For example, alkyl bromide as the simplest organic halides has been used for model of photodissociation dynamics. The A-band of alkyl bromide arises from the C-Br bond localized σ^* → n transition and consists of three overlapping transitions to repulsive states (³Q₁, ³Q₀, and ¹Q₁: on ascending order of excitation energy). The dominant transition in the A-band is to the ³Q₀₊ state which correlates to the Br^*(²P_1/2) products, suggesting the spin-orbit ground Br(²P_3/2) atom formation arises as a results of nonadiabatic coupling between the ³Q₀₊ and ²Q₁ PESs via a conical intersection along the C. Br bond coordinate

No abstract available

[en] A topological analysis of HF/6-31++G**//HF/6-31G* electron distributions on diverse conformers of 36 linear fluoroalkanes of formula CH_nF_3-n(CH₂)_mCH₃ was carried out within the atoms in molecules (AIMs) formalism. Group energy additivity of molecular energies was found in spite of lack of energy transferability. Cooperative effects due to stepwise fluorination on carbon 1 that appear to be around to 90 kJ mol^-1 according to traditional analysis based upon fitted group energies, exceed 370 kJ mol^-1 when obtained from AIMs energies. Mean values of atomic properties and empirical relationships between concrete atomic properties lead to a definition of transferable fragments. It was found that the effect of fluorine atom on the chain is appreciable at further carbons for trans than for gauche arrangements, whereas effects on the hydrogen atoms give rise to an oscillatory behaviour (related to F-H interatomic distances) displayed along the whole chain

No abstract available

[en] The aluminium chloride is synthesized by direct chlorination of aluminium, in agreement with the following reaction: Al(s) + 3/2 Cl₂ AlCl₃ (s,g).The present work focuses on the preparation of aluminium chlorides by two methods: (a) Chlorination of 6061 aluminium alloy with gaseous chlorine in sealed containers, filled with different pressures of gas, from 0.8 to 74 Kpa and in the range of temperature between 200⁰ and 500⁰C.(b) Chlorination of the same alloy in chlorine flow between 150⁰ and 400⁰C.In the sealed systems, the hexahydrated aluminium trichloride predominated over the anhydrous form. For pressures lower than 14 Kpa and temperatures under 250⁰C, the chloride didn't appear.The residues were rich in aluminium, chlorine and magnesium.In the other systems, the anhydrous chloride was found in the areas of the reactor of temperatures above 100⁰C, for all the thermal treatments. The waste was composed by CrCl₃ and AlCl₃.6H₂O.The influence of the chlorine pressures and the heating temperature over the characteristics of the product, was studied.The characterization techniques were x-ray diffraction and energy dispersive spectroscopy, and the evolution of the structure was followed by scanning electron microscopy

[en] Under isothermal conditions at 5O0 deg C and partial pressure 1 atm, the process of fluorination of rare-earth metals is studied using the gravimetric method. It is shown that the metals studied can be broadly divided into three groups by their behaviour in the flow of fluorine. The first group includes Ce which burns in fluorine, and also Psub(r), Tb, La and Sm reacting with relatively high rates. The second group consists of metals featuring a moderate fluorination rate, viz Y and Gd. The third group includes chiefly metals from yttrium subgroup - Dy, Mo, Er, Tm, Yb and Nb, characterized by a slow rate of reaction with fluorine. On the heaviest metals, protective films of fluorides are formed which makes these metals resistant in the fluorine atmosphere

[en] Chlorine is not just one of many chemical feedstocks which is used in a few definitely harmful products like PVC or CFC but is irrelevant in all other respects. Just the opposite is true: There is hardly any product line of the chemical industry that can do without chlorine, from herbicides and pesticides to dyes, plastics, pharmaceuticals, photographic atricles, and cosmetics. Chlorine is not only a key element of chemical production but also an ubiquitous element of everyday life in civilisation. There are even many who would agree that the volume of chlorine production is an indicator of the competitive strength and national wealth of a modern society. By now, however, it has become evident that the unreflected use of chlorine is no longer ecologically acceptable. The consequences of a chlorine phase-out as compared to the continued chlorine production at the present level were investigated scientifically by a PROGNOS team. They are presented in this book. (orig.)

[en] In this paper, we report preliminary data for the first direct evidence of a free radical formed from Mu reactivity with Br₂ in the gas phase, in N₂ moderator at a total pressure of 3 bar. A new experimental setup and target vessel for μSR studies of reactive compounds, such as the halogens and hydrogen halides, suitable as well for RF measurements, is described. The experimental data, obtained from a longitudinal field repolarization curve, yields a hfc of 1770 MHz. We tentatively identify this as the [BrMuBr] radical, a non-conventional bond system, arising from the combination of a van der Waals interaction and dynamics on a repulsive surface. Studies of the dynamics and hfcs of possible radicals, which in principal could form, are also outlined here