Robust half‐metallicity of AlCoN and AlNiN

Theoretical investigations of Al_1‐xCo_xN and Al_1‐xNi_xN (x = 0.25) in the zinc blende phase are presented. The robustness of half metallicity of these compounds with correlation to their lattice compressions is discussed. The results show that both compounds retain their half‐metallic nature (conductor for spin up state and semiconductor for spin down state) with their lattice compressions up to certain critical lattice constants. Abrupt changes in the electronic and magnetic properties are observed at these robust transition lattice constants (RTLCs). These compounds lose their integer magnetic moments of 4μ_β for Al_1‐xCo_xN and 3 μ_β for Al_1‐xNi_xN at RTLCs. The calculated RTLC for Al_0.75Co_0.25N is 4.4 Å and for Al_0.75Ni_0.25N is 4.2 Å. The possible compression in the lattice constants from their relaxed states while maintaining their half‐metallic nature is up to 4% for both compounds. © 2012 Wiley Periodicals, Inc.     

Polymerization of vinyl chloride with half‐titanocene/methylaluminoxane catalysts

The polymerization of vinyl chloride (VC) with half‐titanocene /methylaluminoxane (MAO) catalysts is investigated. The polymerization of VC with the Cp*Ti(OCH₃)₃/MAO catalyst (Cp* = η⁵‐pentamethylcyclopentadienyl) afforded high‐molecular‐weight poly(vinyl chloride) (PVC) in good yields, although the polymerization proceeded at a slow rate. With the Cp*TiCl₃/MAO catalyst, the polymer was also obtained, but the polymer yield was lower than that with the Cp*Ti(OCH₃)₃/MAO catalyst. The polymerization of VC with the Cp*Ti(OCH₃)₃/MAO catalyst was influenced by the MAO/Ti mole ratio and reaction temperature, and the optimum was observed at the MAO/Ti mole ratio of about 10. The optimum reaction temperature of VC with the Cp*Ti(OCH₃)₃/MAO catalyst was around 20 °C. The stereoregularity of PVC obtained with the Cp*Ti(OCH₃)₃/MAO catalyst was different from that obtained with azobisisobutyronitrile, but highly stereoregular PVC could not be synthesized. From the elemental analyses, the ¹H and ¹³C NMR spectra of the polymers, and the analysis of the reduction product from PVC to polyethylene, the polymer obtained with Cp*Ti(OCH₃)₃/MAO catalyst consisted of only regular head‐to‐tail units without any anomalous structure, whereas the Cp*TiCl₃/MAO catalyst gave the PVC‐bearing anomalous units. The polymerization of VC with the Cp*Ti(OCH₃)₃/MAO catalyst did not inhibit even in the presence of radical inhibitors such as 2,2,6,6,‐tetrametylpiperidine‐1‐oxyl, indicating that the polymerization of VC did not proceed via a radical mechanism. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 248–256, 2003     

Liquid Phase Hydrogenation of t,t,c‐1,5,9‐Cyclododecatriene over Ni/MCM‐41 and Ni/SiO2 Catalysts

Ni‐loaded pure siliceous and aluminosilicate MCM‐41 (Ni/MCM‐41) and nickel‐loaded silica (15Ni/SiO₂) were synthesized via wet impregnation and were characterized by various techniques. The H₂ consumption in the TPR analysis was found to be proportional to the Ni amount in the calcined samples. After reduction the average Ni particle sizes of 15Ni/MCM‐41 and 15Ni/SiO₂ were 9–12 and 16 nm, respectively, by means of XRD and TEM measurements. All catalysts owned weak and intermediate Lewis acid sites that increased slightly with increasing the Ni amount and the Al content. In the liquid phase hydrogenation of t,t,c‐1,5,9‐cyclododecatriene over Ni/MCM‐41, the catalytic activity was parallel to the Ni content and enhanced slightly with the acid amount of the catalysts. Consequently, it was proposed that the Ni metallic sites contributed the major effect to the catalytic activity while the Lewis acid sites promoted a small but significant influence on the catalytic performance. It is noteworthy that all 15Ni/MCM‐41 catalysts exhibited remarkably higher activity than that of the conventional 15Ni/SiO₂ catalyst.     

Vapour Phase Hydrogenation of Cinnamaldehyde over Nano Ni and Ni/SiMCM‐41 Catalysts

Ni nanoparticles (Ni(1) and Ni(2)) and Ni loaded SiMCM‐41 (15Ni/SiMCM‐41) were prepared and characterized with XRD, TEM, N₂ adsorption, CO chemisorption, and H₂‐TPR. The Ni specific surface area followed the order of 15Ni/SiMCM‐41 > Ni(1) >> Ni(2), whereas the Ni particle size exhibited the opposite trend. These catalysts were utilized for vapour phase hydrogenation of cinnamaldehyde at 1 atm and 200 °C in a fixed‐bed, down flow reactor. The main products include hydrocinnamaldehyde, styrene, ethylbenzene, and 2‐phenyl‐1‐propanol. The catalytic activity decreased in the same order as that of Ni specific surface areas. The SiMCM‐41 support possessed very large surface area, leading to enhanced dispersion and specific surface area of Ni nanoparticles. As a result, the 15Ni/SiMCM‐41 catalyst exhibited the highest activity. Based on the investigation of reaction pathways, it is important to emphasize that both hydrogenation and hydroelimination of formaldehyde (hydrodeformylation) occur in the vapour phase reaction.     

Fabrication of Al/AlN nano‐composite layers by friction stir processing of 6061 Al‐T6 substrate

Friction stir processing was employed for the production of Al/AlN nano‐composite layers on a 6061 Al‐T6 substrate. Nano‐sized AlN powder was inserted in a groove in the middle length of the substrate. Defect‐free layers were achieved using tool rotation and substrate advancing speeds in the range of 900–1400 rpm and 63–310 mm/s, respectively. Subsequent passes were conducted to break‐up AlN clusters that formed in a non‐uniform fashion after initial pass. The grain size of aluminum matrix was found to decrease by the introduction of AlN powder. A nano‐composite layer with near uniform dispersion of nano‐sized AlN reinforcements with a ~9.6% volume fraction was achieved in a matrix of fine dynamically restorated Al grains with a mean size of ~2.5 µm after three subsequent passes. This layer showed an average micro hardness value of ~164 HV (much greater than ~103 HV of the underlying substrate). In addition, the nano‐composite layer exhibited superior dry sliding wear performance against hardened steel compared to that of 6061‐T6 substrate. Increasing tool rotation and substrate advancing speeds were found to decrease the AlN content of the processed layer possibly due to increasing in powder scattering by the pin tool. This was associated with a decrease and increase in hardness values and wear‐loss data, respectively. Copyright © 2014 John Wiley & Sons, Ltd.     

XPS study of impurities in Si‐doped AlN film

This paper reports an XPS study of impurities in a 100‐nm‐thick AlN film grown by metalorganic chemical vapor deposition (MOCVD) under low pressure on the n‐type 6H‐SiC substrate. The Si‐doped AlN film was characterized by the X‐ray photoelectron spectroscopy (XPS) in a high vacuum system, which reveals the content distribution and chemical states of impurities along depth. The XPS analysis of AlN film before and after argon‐ion etching indicates that there always exist Ga, O and C contaminations in AlN film. Especially, O contamination on the AlN film surface is mostly introduced during the growth of AlN layer by MOCVD. Meanwhile, most of O atoms bind with Al or Ga in Al―O and Ga―O chemical states. In particular, the Ga atoms in AlN film are always in two chemical states, i.e. Ga―Ga bond and Ga―O bond, which demonstrates that the aggregation of Ga is accompanying with AlN growth. Copyright © 2016 John Wiley & Sons, Ltd.     

Efficient ethylene/norbornene copolymerization by half‐titanocenes containing imidazolin‐2‐iminato ligands and MAO catalyst systems

Ethylene copolymerizations with norbornene (NBE) using half‐titanocenes containing imidazolin‐2‐iminato ligands, Cp′TiCl₂[1,3‐R₂(CHN)₂C?N] [Cp′ = Cp ( 1 ), ^tBuC₅H₄ ( 2 ); R = ^tBu ( a ), 2,6‐ⁱPr₂C₆H₃ ( b )], have been explored in the presence of methylaluminoxane (MAO) cocatalyst. Complex 1a exhibited remarkable catalytic activity with better NBE incorporation, affording high‐molecular‐weight copolymers with uniform molecular weight distributions, whereas the tert‐BuC₅H₄ analog ( 2a ) showed low activity, and the resultant polymer prepared by the Cp‐2,6‐diisopropylphenyl analog ( 1b ) possessed broad molecular weight distribution. The microstructure analysis of the poly(ethylene‐co‐NBE)s prepared by 1a suggests the formation of random copolymers including two and three NBE repeating units. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 2575–2580     

The syndiospecific polymerization of styrene in the presence of fluorine‐containing half‐sandwich metallocenes

The syndiospecific polymerization of styrene was investigated with the fluorine‐containing half‐sandwich complexes η⁵‐pentamethylcyclopentadienyl titanium bis(trifluoroacetate) dimer, η⁵‐octahydrofluorenyl titanium tristrifluoro‐acetate, η⁵‐octahydrofluorenyl titanium dimethoxymonotrifluoroacetate, and η⁵‐octahydrofluorenyl titanium tris(pentafluorobenzoate) in comparison to known chloride and methoxide complexes in the presence of relatively low amounts of methylalumoxane and triisobutylaluminum. After the selection of effective reaction conditions for a solvent‐free polymerization, the following orders of decreasing polymerization activity of the titanium complexes can be observed: for pentamethylcyclopentadienyl compounds, Cp*Ti(OMe)₃ > [Cp*Ti(OCOCF₃)₂]₂O ≈ Cp*TiCl₃, and for octahydrofluorenyl compounds, [656]Ti(OMe)₃ > [656]Ti(OCOC₆F₅)₃ > [656]Ti(OCH₃)₂(OCOCF₃) > [656]Ti (OCOCF₃)₃. The [656]Ti complexes, showing the highest polymerization conversions at 70 °C and in comparison with the Cp* Ti compounds, turned out to be highly efficient catalysts for the syndiospecific styrene polymerization. The fluorine‐containing Cp* and [656]Ti complexes lead to much higher molecular weights than the chloride and methoxide compounds because of a reduction in chain‐limiting transfer reactions. The introduction of only one fluorine‐containing ligand into the coordination sphere of the metal compound is obviously sufficient for a significant increase in molecular weight. The active polymerization sites of the [656]Ti complexes with methylalumoxane and triisobutylaluminum are extremely stable during storage at room temperature in regard to their polymerization activity. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 2428–2439, 2000     

Reaction of CO2 and H2 in the presence of Co and Ni catalysts

The activity and selectivity of 10 % Co/support and 10 % Ni/support catalysts (where the support is A1₂O₃, SiO₂, C) in the synthesis of hydrocarbons from CO₂ and H₂ were studied. The extent of conversion of the starting mixture and the yield of methane were shown to depend on the composition of the catalytic system. Cobalt catalysts with various types of carbons as supports are the most active. They permit the synthesis of methane in yields up to 70 % of the theoretical value.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 3, pp. 482–484, March, 1993.     

Combination of Dispersive Liquid‐Liquid Microextraction with Flame Atomic Absorption for Determination of Trace Ni and Co in Water Samples and Vitamin B12

A dispersive liquid‐liquid microextraction method based on the dispersion of 1,2‐dichlorobenzene as an extraction solvent into an aqueous phase in the presence of ethanol as a dispersive solvent for the preconcentration of Co²⁺ and Ni²⁺ ions is discussed. 1‐Nitroso 2‐naphtol was used as a chelating agent prior to the extraction and the preconcentrated analyte was determined by flame atomic absorption spectrometry. The effect of various experimental parameters including the extraction and dispersive solvent type and volume, pH, amount of the chelating agent, etc. on the microextraction and complex formation was investigated for finding the optimum conditions. The enhancement factors were about 61.9 and 51.8, the calibration graphs were linear in the range of 10‐150 μgL^?1 and 10‐250 μgL^?1 with detection limits of 2.42 μgL^?1 and 1.59 μgL^?1, and RSD (n = 5) of 3.08% and 2.17% for cobalt and nickel, respectively. The method was successfully applied to the determination of Co and Ni in water and vitamin B₁₂.     

电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰

采用电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰的含量。优化的试验条件如下:1柠檬酸溶液用量为2mL;2过氧化氢溶液用量为12mL;3称样量为0.100 0g;4氨水溶液用量为2mL。选择镍、铁、钴、锰的分析谱线分别为221.647,233.280,228.616,259.373nm。4种元素在一定的质量浓度范围内与其发射强度呈线性关系,方法的检出限(3s/k)在0.018~0.083mg·L-1之间。方法应用于标准物质(JBWY05901)的分析,测定值与认定值相符。方法用于生产样品和合成样品的分析,测定值的相对标准偏差(n=6)在0.72%~3.9%之间。     

Catalytic activity in the oxidative dehydrogenation of ethane over Ni and/or Co molybdate catalysts: Synthesis and characterization

Ni and/or Co molybdate based catalysts were synthetized by co-precipitation for the oxidative dehydrogenation of ethane reaction. The catalysts were characterized by several techniques such TGA-DTA, HT-XRD, XRD, LRS, N₂ adsorption, XPS and TPR. The results showed that the addition of Ni or Co to MMoO₄matrices (M=Ni or Co) led to a high dispersion of additives into the molybdenum matrix without the formation of a significant amount of other bulk metal oxides. Compared to the pure MMoO₄, the modified molybdenum (Ni_0.5Co_0.5MoO₄) presents a higher thermal stability (up to 1000 °C). It has a lower BET surface area and higher reduction temperature compared to those of the NiMoO₄ sample. In the ODH of ethane, Ni_0.5Co_0.5MoO₄ shows a lower catalytic activity compared to that of MMoO₄ samples; however, the ethylene selectivity is enhanced (exceeding 90%). As a result, these series of catalysts show improved efficiency for ethylene production in the ethane ODH reaction.     

Cell‐based studies of the first‐in‐class half‐sandwich Ir(III) complex containing histone deacetylase inhibitor 4‐phenylbutyrate

We report on a cytotoxic half‐sandwich iridium(III) complex [Ir(η⁵‐Cp^ph)(phen)(PB)]PF₆ ( 1‐PB ), containing a monodentate coordinated O‐donor 4‐phenylbutyrato ligand (PB) belonging to the family of histone deacetylase inhibitors (HDACi); HCp^ph = (2,3,4,5‐tetramethylcyclopenta‐2,4‐dien‐1‐yl)benzene, phen = 1,?10‐phenanthroline. The solution behaviour studies indicated that complex 1‐PB partially hydrolysed in the mixture of methanol and water (1:4, v/v), resulting in the release of the PB ligand. The extent of the PB ligand release increased in the presence of 2 molar equiv. of the reduced glutathione (GSH). Complex 1‐PB exhibited comparable in vitro cytotoxicity against the cisplatin‐sensitive (IC₅₀ = 15.8 μM) and ‐resistant (IC₅₀ = 13.0 μM) variants of the A2780 human ovarian carcinoma cells, while its potency against the MRC‐5 human normal fibroblast cells was markedly lower (IC₅₀ = 124.1 μM). The cytotoxicity studies revealed an ability of complex 1‐PB to overcome the acquired resistance against cisplatin, with the resistance factor (RF = 0.8) being markedly lower than for complex 1‐Cl (RF = 1.8) and cisplatin (RF = 2.9). The A2780 cell‐based flow cytometry experiments showed different cell cycle modification induced by complex 1‐PB and cisplatin, induction of production of reactive oxygen species, and higher mitochondria membrane potential depleted cell populations after the treatment by complex 1‐PB as compared with cisplatin. In the cell‐free assay, complex 1‐PB inhibited the HDAC activity to ca 66% as compared to ca 74% valid for NaPB. The [Ir(η⁵‐Cp^ph)(phen)(H₂O)]²⁺ species ( 1‐OH ₂ ), representing the hydrolysis product of both complexes 1‐PB and 1‐Cl , induced hydroxyl radical from the hydrogen peroxide, as proved by the EPR spin trapping studies with the 5‐(diethoxyphosphoryl)‐5‐methyl‐1‐pyrroline‐N‐oxide (DEPMPO) spin trap.     

Der Chemische Transport ternärer intermetallischer Phasen in den Systemen Cr/Co/Ge und Co/Ta/Ge

Chemical Vapor Transport of Intermetallic Systems. 11 Chemical Vapor Transport of Ternary Intermetallic Phases in the Systems Cr/Co/Ge and Co/Ta/Ge By means of chemical vapor transport using iodine as transport agent it is possible to prepare a number of ternary intermetallic compounds in the system Co/Cr/Ge as single crystals. The transport behaviour in this ternary system is related to that in the binary systems. Some informations are given about transport phenomena in the systems Co/Cr and Co/Ta/Ge.     

Syndiotactic polymerization of styrene catalyzed by alkenyl‐substituted cyclopentadienyltitanium trichlorides

CH₂?CHCH₂CpTiCl₃ (1), CH₂?CHCH₂CH₂CpTiCl₃ (2) and CH₃CH₂CH₃CpTiCl₃ (3) have been synthesized and characterized. The influence of the alkenyl substituent groups on the catalyst activities in the syndiotactic polymerization of styrene was investigated. The catalyst activities decreased in the order CH₂?CHCH₂CH₂CpTiCl₃ > CH₃CH₂CH₂CH₂CpTiCl₃ > CH₃CH₂CH₂CpTiCl₃ > CH₂?CHCH₂CpTiCl₃ (Cp?C₅H₄). By using complex 1, the dependence of the activity on the concentration of methylaluminoxane, triisobutylaluminum and diisobutylaluminum hydride was investigated. Copyright © 2003 John Wiley & Sons, Ltd.     

Kinetic and Theoretical Studies on Ni0/N‐Heterocyclic Carbene‐Catalyzed Intramolecular Alkene Hydroacylation

A combined kinetic and theoretical study was conducted in order to clarify the details on the reaction mechanism for Ni⁰/It Bu‐catalyzed intramolecular alkene hydroacylation. The results confirm the hypothesis that this intramolecular hydroacylation proceeds through an oxanickelacycle key intermediate.     

Efficient introduction of aromatic vinyl group by incorporation of divinylbiphenyl,p‐divinylbenzene in syndiospecific styrene polymerization using aryloxo‐modified half‐titanocene catalysts

An efficient introduction of aromatic vinyl group into syndiotactic polystyrene has been achieved by incorporation of 3,3′‐divinylbiphenyl, p‐divinylbenzene (DVB) in syndiospecific styrene polymerization using aryloxo‐modified half‐titanocenes, Cp′TiCl₂(O‐2,6‐ⁱPr₂C₆H₃) (Cp′ = ^tBuC₅H₄, 1,2,4‐Me₃C₅H₂), in the presence of MAO. The resultant polymers possessed high molecular weights with uniform molecular weight distributions, and the DVB contents could be varied by the initial feed molar ratios (6–23 mol %) without decrease in the M_n values. The syndiotactic stereo‐regularity and presence of the vinyl groups were confirmed by NMR spectra. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1902–1907     

Synthesis and characterization of norbornene–ethylene–styrene terpolymers with a substituted ansa‐fluorenylamidodimethyltitanium‐based catalyst

This article reports a synthetic method for a norbornene–ethylene–styrene (N‐E‐S) terpolymer, which has not been well investigated so far, via incorporation of styrene (S) into vinyl‐type norbornene–ethylene (N‐E) copolymers catalyzed by a substituted ansa‐fluorenylamidodimethyltitanium [Me₂Si(3,6‐tBu₂Flu)(tBuN)]TiMe₂ catalyst ( I ) activated with a [Ph₃C][B(C₆F₅)₄]/Al(iBu)₃ cocatalyst at room temperature in toluene. The resulting terpolymerization product contained the targeted N‐E‐S terpolymer and the contaminated homopolymers, which were then able to be completely removed by solvent fractionation techniques. While homopolystyrene was easily extracted by fractionation with methylethylketone as a soluble part, homopolyethylene and a trace amount of homopolynorbornene could be perfectly separated by fractionation with chloroform as insoluble parts. The detail characterizations of a chloroform‐soluble polymer with gel permeation chromatography, nuclear magnetic resonance, and differential scanning calorimetry analyses proved that it contained a true N‐E‐S terpolymer with long N‐E sequences incorporated with isolated or short styrene sequences. The homogeneity of the morphology together with a single glass transition temperature that proportionally decreased with the increase of the styrene contents indicated that the N‐E‐S terpolymer obtained in this work is a random polymer with an amorphous structure. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 2765–2773, 2007     

Theoretical study of magnetic coupling interaction in terephthalato‐bridged Ni(II) binuclear systems

The density functional theory combined with broken‐symmetry approach has been successfully extended into the study of the long‐range weak coupling interaction in a binuclear Ni(II) complex bridged by terephthalate dianion. The calculated magnetic coupling constant (?0.27 cm^?1) is well in agreement with the experimental one (?0.33 cm^?1). The relative magnitude of the energies of different spin states has been obtained. The spin delocalization and spin polarization occur between two Ni(II) ions, based on the analysis of the spin density distribution. Weak antiferromagnetic behavior in such a system may result from the competition between spin delocalization and spin polarization where the former is dominant. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004