Nickel(I) complex as the final product of the sequence of spontaneous transformations in the system Ni(allyl)2-(2,6-diisopropylphenyl)diazabutadiene

A reaction of Ni(Allyl)₂ with bis(2,6-diisopropylphenyl)diazabutadiene gave an imino amide allyl nickel(II) complex (I). Complicated rearrangements of the imino amide ligand in the coordination sphere of complex I spontaneously yielded a paramagnetic Ni(I) ??-allyl complex as a final reaction product. The nickel complexes produced in this system were studied by EPR, IR, and 2D NMR spectroscopy and mass spectrometry. Structure I was examined by X-ray diffraction.     

Role of paramagnetic Ni(I) and Ni(III) complexes in catalytic reactions of unsaturated hydrocarbons

By analyzing experimental data collected by systematic investigation of Ni(I) complex formation conditions, it is demonstrated that, when a system simultaneously contains Ni(0) and Ni(II) complexes, whether cationic or electroneutral, stabilized by olefinic or organoelement ligands, the complexes undergo comproportionation to form Ni(I) complexes. Using individual Ni(II) complexes as examples, it is shown that the spontaneous decomposition of hydrido and organometallic Ni(II) complexes yields Ni(I) complexes. The Ni(I) and Ni(III) complexes are involved in the catalytic cycles of reactions of olefins and acetylenes.     

Influence of the order of introduction of protonic acids on the formation of active complexes in the Ni(PPh3)4/BF3 · OEt2 catalytic system

The influence of the order of introduction of promoters (complex protonic acids) on the formation of active complexes in the Ni(PPh₃)₄/BF₃ · OEt₂ catalytic system and the activity of these systems in ethylene oligomerization have been studied. The activity of the systems in which nickel exists mainly as cationic Ni(I) complexes is more than one order of magnitude higher than the activity of the systems where nickel exists mainly in the form of Ni(II) hydride complexes. The role of alcohols as promoters in the Ni(PPh₃)₄/BF₃ · OEt₂ catalytic system is elucidated. The alcohols are the source of Ni(II) hydrides and, more importantly, the source of strong Brønsted acids, which efficiently ensure the coordinative unsaturation of the cationic Ni(I) complexes.     

Reaction of the acrylic acid and 1-vinylimidazole copolymer with CuCl2 in aqueous solution

The reaction of acrylic acid—1-vinylimidazole copolymer with CuCl₂ in an aqueous medium was investigated by potentiometric titration and UV and ESR spectroscopy. The complex formation involves both the azole units and the carboxy groups. The Cl^– ions are also incorporated in the inner sphere of the complexes, their removal by dialysis resulting in an increase in the coordination capacity of the carboxylate groups.     

Structure of Free Radicals Formed under X-ray Irradiation of Organic Polymeric Acids

The structure of free radicals formed under X-ray irradiation of polyacrylic and polymetharcylic acids and poly-3-vinyltetrazole was studied by ESR spectroscopy. In polymerization of polymethacrylic acid, the conditions of the polymer recovery from the solution affect the nature of the radiolysis products.     

Formation of a hydrogenation catalyst in the cobalt acetylacetonate-triethylaluminum system

Based on the results obtained using chemical, kinetic, and physical techniques (EPR, IR, and UV spectroscopy; transmission electron microscopy; and XRD analysis), the formation of active species in the triethylaluminum-bis(tris)(acetylacetonato)cobalt system, which is known to be a hydrogenation catalyst, has been considered. It has been found that nanosized particles are formed in this system; the core of these particles consists of Co⁰ atoms stabilized by a shell containing Et₂Al(acac), AlEt₃, and their reaction products. The extremal dependence of the hydrogenation activity of the system on the Al/Co ratio is primarily due to changes in the composition of the protective shell of nanosized particles.     

Theory of perfect plasticity of composite materials,taking account of volume compressibility

The practical importance and timeliness of the study of the mechanical macroscopic behavior of composite microinhomogeneous media are determined by its ability to give criteria for estimating the limiting load of various structural elements, the flow of multiphase dispersed systems, the deformation of materials made by powder metallurgy methods, etc. The theoretical prediction of the properties of composites is generally most effectively realized when their structural representations are based on the theory of random fields. Application of the strong isotropy hypothesis [1] for the statistical averaging of certain relations of a perfectly plastic body with microstructure permits the determination of its macroscopic yield surface.Translated from Zhurnal Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 3, pp. 164–167, May–June, 1981.     

Effect of doping a cadmium sulfide-zinc sulfide solid solution with copper ions on its physicochemical properties and catalytic activity in hydrogen recovery from aqueous solutions under the action of visible radiation

Cu _y Cd_0.3Zn_0.7S_{1 + y} photocatalysts intended for hydrogen recovery from aqueous solution under the action of visible radiation have been synthesized and characterized. The effect of the pH of the aqueous solution of Na₂S-Na₂SO₃ on the rate of the photocatalytic reaction has been investigated. The highest activity is shown by the sample containing 1 mol % copper. With this photocatalyst, the quantum efficiency of the reaction under optimum conditions is 23.5%.