Zinc reaction with diphenylantimony and diphenylbismuth chlorides in aprotic solvents

Products of zinc oxidation with diphenylantimony and diphenylbismuth chlorides in aprotic solvents are established. The effective adsorption constants of the reagents on the metal surface and the rate constants and activation energies of the processes under study are calculated.     

Dynamics of a Recurrent Spiking Neural Network in the Two-Alternative Choice Task

Radiophysics and Quantum Electronics - We have revealed the dynamic mechanism of solving a cognitive task of two-alternative choice by an artificial recurrent network of spiking neurons. The...     

Effects of structure-dynamics correlation on hierarchical transitions in heterogeneous oscillatory networks

The impact of frequency-degree and amplitude-degree correlation is studied for heterogeneous networks of coupled Stuart–Landau oscillators. It is shown that increasing coupling strength gives rise to hierarchical processes of oscillation quenching. In case of frequency-degree correlated networks, higher-frequency oscillators gradually become almost quenched while low-frequency ones still remain oscillating. In case of amplitude-degree correlated networks, there appear three distinct domains, two contain low-amplitude oscillations with positive and negative means, and the third includes high-amplitude oscillations around the origin.     

Low-noise wide-band hot-electron bolometer mixer based on an NbN film

We develop and study a hot-electron bolometer mixer made of a two-layer NbN–Au film in situ deposited on a silicon substrate. The double-sideband noise temperature of the mixer is 750K at a frequency of 2.5 THz. The conversion efficiency measurements show that at the superconducting transition temperature, the intermediate-frequency bandwidth amounts to about 6.5GHz for a mixer 0.112 μm long. These record-breaking characteristics are attributed to the improved contacts between a sensitive element and a helical antenna and are reached due to using the in situ deposition of NbN and Au layers at certain stages of the process.     

Synthesis of 1-mono- and 1,2-bisacylpyrazolidines and 1-arylsulfonylpyrazolines

Study of a reaction of 1,5-diazabicyclo[3.1.0]hexanes with acyl and sulfonyl chlorides in organic or aqueous organic media in the presence of inorganic bases resulted in development of new simple one-step methods for the preparation of 1-mono- and 1,2-bisacylpyrazolidines and 1-arylsulfonylpyrazolines.     

Adsorption of solvent and oxidant molecules on magnesium surface: effect on the electronic structure and reactivity of magnesium in reactions of Grignard reagent formation

The effect of adsorption of the oxidant (EtBr) and aprotic dipolar solvent molecules on the electronic structure and properties of Mg _n (n ≤ 50) clusters simulating the surface of metallic magnesium was studied by the B3PW91/6-31G(d) density functional method. It was found that the work function of an electron from the cluster monotonically decreases as the donor ability of the adsorbed molecules increases. The experimentally measured rate of the magnesium oxidation by EtBr correlates with the negative Mulliken charge density of the first coordination sphere of the surface adsorption site. The results obtained are in agreement with the experimentally determined work function of electron from metals during adsorption from the gas phase. Presumably, the rate-limiting step of the Grignard reagent formation is the surface oxidation reaction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 458–469, March, 2008.     

Features of photolytic transformation of [4-(2-methyl-5-t-butyl-cyclohexadiene-1,5-dion-3,4-yl)-3-methyl-6-<Emphasis Type="Italic">tert</Emphasis>-butyl-catecholato]triphenylantimony(V)

Photolysis of [4-(2-methyl-5-tert-butyl-cyclohexadiene-1,5-dion-3,4-yl)-3-methyl-6-t-butyl-catecholato] triphenylantimony(V) in toluene by irradiation with the light of wavelength 546 nm leads to excitation of the molecule of parent compound which reacts with a molecule of Ph3SbCatQ affording 4,4′-di-(3-methyl-6-tert-butyl-o-benzoquinone) and 4,4′-di[(3-methyl-6-tert-butyl-catecholato)triphenylantimony(V)]. The formed compounds react with each other returning the system into the initial state. Action of light of wavelength 313 and 405 nm on the initial reaction mixture leads to the formation of carbon monoxide, Ph3SbCatCatSbPh3 and the products of photolytic transformation of 4,4′-di(3-methyl-6-tert-butyl-o-benzoquinone).     

Special features of photolytic transformation of tin heteropolymetallic catecholate complexes

The photolysis of bis(dicarbonylcyclopentadienyliron)(3,6-di-tert-butylcatecholato)tin(IV), bis(dicarbonylcyclopentadienylmolybdenum)(3,6-di-tert-butylcatecholato)tin(IV), and bis(dicarbonylcyclopentadienyltunsten)(3,6-di-tert-butylcatecholato)tin(IV) in solutions of saturated hydrocarbons was studied. Kinetic parameters of the transformation of these compounds under the action of a monochromatic radiation with a wavelength of 313 nm were determined. Products of their transformation formed in the course of the irradiation were identified, and the probable mechanism of their photodecomposition was proposed.