Electronic and geometric structure of the protonated forms of nickel β-diketonates

The effect of protonation on the electronic and spatial structure of nickel malonodialdehynate Ni(Mal)₂ and acetylacetonate Ni(Acac)₂ were studied by quantum chemical density functional theory (DFT) method. The metal ring geometry, the energies and the composition of molecular orbitals (MO), the effective charges on atoms, and the total overlap populations were determined, and the possible proton location sites were identified. The variation of the MO energy depending on the electron density distribution on the protonated and non-protonated ligands was considered. Proton addition to one of the oxygen atoms was shown to be most likely.     

Electrodeposition,properties, and composition of rhenium–nickel alloys

The process of deposition of the Re–Ni alloy, its current efficiency, and the alloy composition are studied as a function of the current density and the solution temperature. The hydrogen content in the deposits, their surface morphology, internal structure, and properties as the cathodic material for HER are examined. It is assumed that besides the high rhenium content, the high catalytic activity of nickel–rhenium alloys is associated with the high degree of their structural disordering.     

Synthesis of cobalt and nickel 6,6′-diphenylbis(dicarbollides)

Russian Chemical Bulletin - 6,6′-Diphenyl derivatives of cobalt and nickel bis(dicarbollide) were synthesized starting from nido-carborane by the insertion—deboronation—insertion...     

Conversion of ethanol into linear primary alcohols on gold,nickel, and gold–nickel catalysts

The direct conversion of ethanol into the linear primary alcohols C _n H_2n+1OH (n = 4, 6, and 8) in the presence of the original mono- and bimetallic catalysts Au/Al₂O₃, Ni/Al₂O₃, and Au–Ni/Al₂O₃ was studied. It was established that the rate and selectivity of the reaction performed under the conditions of a supercritical state of ethanol sharply increased in the presence of Au–Ni/Al₂O₃. The yield of target products on the bimetallic catalyst was higher by a factor of 2–3 than that reached on the monometallic analogs. Differences in the catalytic behaviors of the Au, Ni, and Au–Ni systems were discussed with consideration for their structure peculiarities and reaction mechanisms.     

Synthesis and crystal structure of dinuclear nickel (Ⅱ) complex

The crystal structure of Ni(Ⅱ) complex with 3-hydroxyl-1, 5-diazacycloheptane-N, N'-diacetate was determined by X-ray diffraction method. Crystal data for Ni2 (C9H14N2O5)2·2H2O: monoclinic, space group P21/n, a = 1.1717(5), b = 0.9794(3), c = 1.2971(2) nm, β= 96.62(3), V= 1.4786(7) nm3, Dc = 1.377 g/cm3, Z = 2,μ=13.321 cm-1 (Mo-Kα), F(000)=640. The final R and Rw are 0.075 and 0.089 respectively. The Ni(Ⅱ) ion forms 2:2 complex with ligand. Two ligands are bridged by two Ni(Ⅱ) atoms which are bridged by two O atoms. Every Ni(Ⅱ) is coordinated by two N atoms and four 0 atoms. The coordination polyhedron of the Ni(Ⅱ) ion is a distorted octahedron.     

Catalytic properties of nickel–yttrium mixed oxides and the influence of ionizing radiation

Some physico-chemical and catalytic properties of NiO–Y₂O₃ cataysts containing various amounts of components in the range 0–100 wt% of one component have been studied before and after 1 MGy gamma or accelerated electron irradiation in air or in water using the hydrogen peroxide decomposition as a test reaction. Both kinds of irradiation led only to a change in surface oxidative ability but did not lead to modification of the catalytic activity of the catalysts. The reduction of the catalysts led to a creation of new kind of catalytic sites.     

Synthesis and spectral properties of β-bromo-substituted nickel(II) tetraphenylporphyrins

Russian Journal of Organic Chemistry - Bromination of (5,10,15,20-tetraphenylporphyrinato)nickel(II) with N-bromosuccinimide in chloroform and chloroform–dimethylformamide mixture and...     

Mössbauer and infrared study of the thermal decomposition of iron and nickel compounds impregnated in alumina

In this work, studies of Fe₃(CO)₁₂ and a mixture of Fe₃(CO)₁₂ and Ni (acac)₂ impregnated in Al₂O₃ were undertaken using Mössbauer and i.r. spectroscopies. In freshly prepared samples, low oxidation species were shown to be present. After thermal decomposition, the data indicate the appearance of aluminum compounds of Fe^II and Fe^III plus superparamagnetic Fe^III. No Fe° species were detected, even under H₂ atmosphere.     

Syntheses, properties and structures of copper and nickel complexes of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate

The reaction of CuCl2-2H2O or NiCl2.6H2O with K2(C5H6S4) [potassium salt of 6,7-dihydro-5H-1,4-dithiepin-2,3-dithiolate] under nitrogen atmosphere resulted in the isolation of [Cu(C5H6S4)2]- or [Ni(C5H6S4)2]- as the tetrabutylammonium salt. Both complexes show characteristic IR and UV-Vis absorptions of transition metal dithiolenes. Cyclic voltammograms contain two waves indicating a two step electrochemical procedure [M(C5H6S4)2]0 = [M(C5H6S4)2]1-= [M(C5H6S4)2]2-. Single crystal structure study has been carried out on the nickel complex. Crystal of [Bu4N][Ni(C5H6S4)2] belongs to monoclinic space group P21/c with a=17.576(5), 6=10.883(2), c=17.773(4) A,B=91.07(2)0, Z=4, and o(calcd.)=1.348 g/cm3. Final result is R=0.059 for 2959 reflections. The NiS4 core exhibits square planar coordination with average Ni-S bond length of 2.134(5) A. There are not anion pairs in crystal. The anions stack along a and c axes while the cations intercalate in them. The nearest S-S contact is 4.429 A. The solid powder ESR s     

Hollow nanodendritic nickel oxide networks prepared by dealloying of nickel–copper alloy

Three-dimensional hollow nanorod network of nickel has been produced by a dealloying process of the electrodeposited nickel–copper alloy with nanodendritic structure. The nanostructured nickel was subsequently heat treated to form the nickel oxide with little change in the original structure. The resulting sample was tested as the high rate anode in a rechargeable lithium battery. It shows the exceptional rate capability, far exceeding that of the counterpart of nickel–copper oxide network with normal solid branches: reversible capacity at the rate of 20.9 A g^?1 is approximately 70 % of the capacity at 0.26 A g^?1 rate.     

Synthesis of nickel—copper—cobalt catalysts for deep oxidation of methane and optimization of their composition

Possibility of fabricating catalysts based on Ni, Cu, Co, and Mn oxides by the impregnation method was examined. The samples obtained were subjected to physicochemical analysis and their catalytic activities in deep oxidation of methane were compared. The composition of the Ni—Cu—Co catalytic system was optimized.     

New preparation of alkyl- and aryl-mono-η5-cyclopentadienylphosphine compounds or iron,cobalt and nickel

Tertiary phosphine stabilized homoleptic alkyl and aryl compounds of Fe, Co and Ni undergo protonolysis of their MC bonds with cyclopentadiene to produce the corresponding mono-η⁵-cyclopentadienyl complexes. Initial low reaction temperatures and the presence of phosphine ligands prevent the formation of metallocenes. This method allows the easy introduction of various achiral and chiral ligands into complexes of this class.     

Adsorptive desulfurization of model diesel fuel over mono-functionalized nickel/γ-alumina and bi-functionalized nickel/cerium/γ-alumina adsorbents

Research on Chemical Intermediates - In this study, the S–M direct interaction and π-complexation mechanisms for selective adsorption of 4,6-dimethyldibenzothiophene (4,6-DMDBT) onto the...     

Pyrolysis-controlled synthesis and magnetic properties of sol–gel electrospun nickel cobaltite nanostructures

Poly(chloropropyl-methyl)silsesquioxanes (PCMSQ) were prepared using the base catalyzed sol–gel processing on methyltrimethoxysilane (MTMS) and 3-chloropropyltriethoxysilane (CPTES) with 5:5, 6:4, and 7:3 molar ratios in methanol and water. The PCMSQ with 6:4 molar ratio of MTMS:CPTES, which has the maximum yield, according to the elemental analysis, was chosen and some chlorine atoms of the chloropropyl groups were changed to different amines by refluxing it with ethylenediamine (en), diethylenetriamine (dien), ortho-phenylenediamine (opda), and 2-imidazolidinethion (imt). The amine grafted PCMSQ were then used to support MoO₂(acac)₂ complex and dien grafted PCMSQ with higher metal content was applied to the epoxidation of cis-cyclooctene with TBHP. The product yields were studied by gas liquid chromatography and the catalytic procedure was optimized for the parameters involved such as the solvent and oxidant. The catalytic activity of this catalyst also was investigated toward epoxidation of some other alkenes. It was also applied to check its reuse ability.

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In this research, micro-spherical poly-organo-silsesquioxane was prepared using the base catalyzed sol–gel processing of methyltrimethoxysilane and 3-chloropropyltriethoxysilane with different molar ratios. The sample which has the maximum yield, was used to graft MoO₂(acac)₂ and for the successful anchoring, some chlorine atoms of the chloropropyl side groups were changed to amines. Then the prepared catalyst with higher molybdenum content was used for the epoxidation of cis-cyclooctene and some other alkenes with TBHP.

     

Effect of nickel and cobalt ions on low temperature synthesis of mullite by sol–gel technique

Synthesis of mullite has been achieved at a low temperature of 600 °C by sol–gel technique in presence of nickel and cobalt ions. Samples were characterized by DTA, XRD, FESEM and FTIR spectroscopy. Mullite formation was found to depend on the concentration of the ions to a certain extent. Highly crystalline spherical mullite particles of dimension 35 nm were obtained at 0.02 M nickel or cobalt concentration.     

Peculiarities of dissociative ionization of alkylcyclopentadienyl nitrosyl π-complexes of nickel

The decomposition of alkylcyclopentadienyl nitrosyl -complexes of nickel, (C₅H₄R)(NO)Ni (R=H, Et,i-Pr, CH₂Ph), under the action of electron impact has been studied. The nature of the nitrosyl ligand has been shown to be the factor determining the main fragmentation pathway which involves the abstraction of an NO molecule. The effect of the nature of the ligand on the ability of the molecular ion (C₅H₄R)LNi⁺ (L=C₅H₄R, C₅H₅, C₃H₅, NO) to rearrange with hydrogen atom migration from one ligand to another has been considered. The structure of the alkyl group R determines a competing fragmentation pathway involving cleavage of the -C-C bond with respect to the cyclopentadienyl ring in the substituent.Translated fromIzyestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1985–1988, November, 1993.     

Sol–gel process of carbon-supported nickel nanoparticles using different solvents and protecting atmospheres

Carbon-supported nickel nanoparticles have been prepared by a sol–gel process under N₂ or H₂ atmospheres using different solvents such as distilled water, ethanol, acetone and 1-propanol. In the aqueous sol–gel process, nickel nanoparticles with pure face-centered-cubic (fcc) phase can be obtained under N₂ atmosphere by using nickel nitrate, tartaric acid and sodium dodecyl sulfonate. When organic solvents are applied, nickel (Π) acetylacetone is required in order to obtain nickel nanoparticles with pure fcc phase under N₂ atmosphere. When the protecting atmosphere is H₂, nickel nitrate can be used to obtain nickel particles with pure fcc phase. Nickel nanoparticles with grain sizes of 4–6 nm in diameter can be prepared by using nickel (Π) acetylacetone [Ni(acac)₂], citric acid and hexadecylamine with solvent being acetone. 1-propanol is also effective in the preparation of nickel nanoparticles in this sol–gel process. We suggest that this sol–gel may be used for other metallic nanocrystals.