Nickel(II) Complexes with Pentane-2,4-dione Bis(4-allylthiosemicarbazone)

Reaction of pentane-2,4-dione with N-(prop-2-en-1-yl)hydrazinecarbothioamide at a 1: 2 molar ratio in ethanol resulted in the formation of a pyrazole derivative. The latter reacted with nickel perchlorate at a 1: 1 molar ratio to form the nickel complex with pentane-2,4-dione bis(4-allylthiosemicarbazone). The same type of nickel complex was obtained as a result of N-(prop-2-en-1-yl)hydrazinecarbothioamide reaction with pentane-2,4-dione and nickel nitrate at a 2: 1: 1 molar ratio. Antimicrobial, antifungal, antioxidant, and anticancer activities of the obtained compounds were studied.     

Spectrophotometric determination of nickel in vegetable oil with ammonium 2-amino-1-cyclohexene-1-dithiocarboate

The reaction between nickel and ammonium 2-amino-1-cyclohexene-1-dithiocarboate in aqueous acetone medium at pH 3.0-8.0 results in a stable dark red complex. The ratio of reagent to nickel in the complex is 2:1 and the formation constant is 7.38 +/- 0.12 x 10(10). Beer's law is obeyed up to 4 microg/ml nickel at the absorption maximum at 535 nm. The apparent molar absorptivity is 2.8 x 10(4) l.mole(-1). cm(-1), and the detection limit is 10 ng/ml nickel. The method is applied to the determination of nickel in vegetable oil.     

Raney nickel reductions—VIII A synthesis of 1:2-benzanthracene and its 3′-methyl and 4-methyl derivatives

1:2-Benzanthracene and the 3′-methyl derivative have been prepared by Raney nickel reduction of the sulphuric esters of the leuco derivatives of 1:2-benzanthraquinone and 4′-chloro-3′-methyl-1:2-benzanthraquinone, followed by dehydrogenation. 3-Hydroxy-1:2-benzanthraquinone was methylated in the 4-position by formaldehyde, sodium hydrosulphite and sodium hydroxide solution (the Marschalk reaction). Simultaneous reduction of the nuclear hydroxyl and quinone groups was effected by Raney nickel reduction of the trisulphuric ester of 3:9:10-trihydroxy-4-methyl-1:2-benzanthracene, and the resultant hexahydro-4-methyl-1:2-benzanthracene was dehydrogenated to 4-methyl-1:2-benzanthracene. The preparation of 3:4:9:10-dibenzopyrene from Mayvat brilliant red AF by Raney nickel reduction of the sulphuric ester of the leuco derivative and subsequent dehydrogenation is described.     

Reversible carbon-carbon bond formation between 1,3-dienes and aldehyde or ketone on nickel(0)

The reversible oxidative cyclization of dienes and aldehydes with nickel(0) proceeded to give eta(3):eta(1)-allylalkoxynickel complexes. The treatment of these complexes with carbon monoxide led to the formation of the corresponding lactone and/or the regeneration of a butadiene and an aldehyde concomitant with the formation of Ni(CO)(3)(PCy(3)). The scission of the nickel-oxygen bond of the allylalkoxy complexes with ZnMe(2) leading to eta(3)-allyl(methyl)nickel was very efficient to suppress the reverse reaction of the oxidative cyclization. The methylated eta(3)-allylnickel compound underwent the reductive elimination. The carbonylative coupling reaction of the eta(3)-allyl(methyl)nickel proceeded as well under a carbon monoxide atmosphere. Similarly, the addition of Me(3)SiCl to eta(3):eta(1)-allylalkoxynickel complexes was also efficient for the inhibition of the reverse reaction. The resulting eta(3)-1-siloxyethylallylnickel complex was treated with carbon monoxides followed by the addition of MeOH to give the expected hydroxyester. This method is efficient as well even for the eta(3):eta(1)-allyl(alkoxy)nickel complex containing acetone as a component, which was so prone to undergo the reverse reaction hampering its isolation. The isolation of the eta(3):eta(1)-allylalkoxynickel complex containing ketone as a component was made easier by the use of heavier butadiene and ketone, such as 2,3-dibenzyl-1,3-butadiene and benzophenone or by the use of cyclobutanone. The reaction with styrene oxide gave the eta(3):eta(1)-allylalkoxynickel containing phenylacetoaldehyde, an isomer of styrene oxide.     

Determination of nickel with 2-(2-quinolylazo)-5-diethylaminoaniline as a chromogenic reagent.

A sensitive, selective and rapid method for the determination of nickel based on a rapid reaction of nickel(II) with 2-(2-quinolylazo)-5-diethylaminoaniline (QADEAA) has been developed. In the presence of pH = 6.0 ammonia-ammonium chloride buffer solution and sodium dodecyl sulfonate (SDS) medium, QADEAA reacts with nickel to form a violet complex having a molar ratio of 1:2 (nickel to QADEAA). The molar absorptivity of the complex is 1.38 x 10(5) l mol(-1) cm(-1) at 595 nm. Beer's law is obeyed in the range of 0.01-0.4 microg/ml. This method had been applied to the determination of nickel with good results.     

Square-planar N2S2NiII complexes with an extended pi-conjugated system

The reaction of a mixture of 2-(1-naphthyl)benzothiazoline (HL1) and 2,6-diphenylbenzo[1,2-d:4,5-d']bisthiazoline (H3L2) with nickel(II) acetate tetrahydrate yielded three kinds of square-planar nickel(II) complexes: one nickel(II) complex with innocent ligands ([Ni(L1)2] (1c)) and two nickel(II) complexes with non-innocent ligands ([Ni(L1-L1)] (1a) and [Ni(L1-L2)] (1b)). The complex 1c has two bidentate-N,S ligands, which are formed via ring opening of HL1. On the other hand, the two complexes 1a and 1b contain a tetradentate-N2S2 ligand, which is created via ring opening of HL1 and H3L2, followed by bond formation between imino carbon atoms. Complexes 1a and 1b show very intense absorptions in the near-infrared (NIR) region, characteristic of square-planar complexes with non-innocent ligands. The third nickel(II) complex having a non-innocent tetradentate-N2S2 ligand ([Ni(L2-L2)] (2)) was prepared from H3L2 and nickel(II) acetate tetrahydrate. The electronic spectrum of 2 exhibits a very intense absorption at 981 nm (epsilon = 3.6 x 10(4) M-1 cm-1), which is significantly red-shifted compared with those of 1a (837 nm and 4.4 x 10(4) M-1 cm-1) and 1b (885 nm and 4.5 x 10(4) M-1 cm-1), indicating the presence of an extended pi delocalization. The reaction of 2,6-bis(3,5-dichlorophenyl)benzo[1,2-d:4,5-d']bisthiazoline (H3L3) with nickel(II) acetate tetrahydrate also led to the formation of a nickel(II) complex with a non-innocent ligand ([Ni(L3-L3)] (3)). While complex 3 is analogous to 2, its electrical conductivity is much higher than that of 2. The molecular structures of 1b, 1c, 2, and 3 were determined by X-ray crystallography.     

Initiation behaviour in hydrogenation of pyrolysis gasoline over presulphided Ni-Mo-Zn/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst

A presulphided treatment was applied to the oxidic Ni-Mo-Zn/Al₂O₃ catalyst (nickel catalyst) in order to avoid thermal run-away during initiation of the hydrogenation of pyrolysis gasoline. The physico-chemical properties of the prepared oxidic nickel catalyst, the reduced and passivated (RP) nickel catalyst and the sulphided (RPS) nickel catalyst were characterised using N₂ adsorption-desorption, X-ray diffraction, temperature-programmed reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The TPR results showed that the reducibility of the RP Ni-Mo-Zn/Al₂O₃ catalyst was improved over the oxidic nickel catalyst. The XPS spectra confirmed the binding energy of the RPS nickel catalyst to be higher than that of the oxidic nickel catalyst. The catalytic performance was evaluated on a fixed-bed reactor (reaction temperature between 30 °C and 70°C, at 2.8 MPa of total pressure and weight hourly space velocity of 2.0 h^?1, the volume of H₂/pyrogasoline = 200: 1). The rising temperature of the RPS nickel catalyst was almost 20°C lower than that of the oxidic nickel catalyst during the initial stage of the hydrogenation reaction. The results indicated that the RPS nickel catalyst exhibited better stability than the oxidic nickel catalyst during the start-up period, thereby providing a better selectivity in long-term operation.     

Spectral and magnetic studies of tin(IV) complexes with nickel(II) thiocarbohydrazones

Tin(IV) chloride derivatives of nickel(II) thiocarbohydrazones were obtained by reacting tin(IV) chloride with nickel(II) thiocarbohydrazones in chloroform medium. All the complexes are greenish coloured solids and appear to be non-electrolytes in DMF. Elemental analyses conform to the 1:1 stoichiometry. Magnetic, electronic and IR spectral information suggest that square planar nickel(II) thiocarbohydrazones have changed their configuration to octahedral as a result of reaction with tin (IV) chloride.     

Room-temperature nickel-catalysed cross-couplings of aryl chlorides with arylzincs

P,N,O-chelate nickel complexes efficiently catalyse the cross-coupling reaction of aryl chlorides with arylzinc reagents in a 1:1 THF-NMP mixture. The reactions proceed at room temperature with low catalyst loading.     

镍(Ⅱ)基双氮杂环卡宾配合物的合成及其晶体结构

以咪唑和取代氯化苄为原料,经氮烷基化反应合成三个氮杂环卡宾(NHC)配体[L1:N,N-二苄基咪唑-2-亚基,L2:N,N-二(4-甲基苄基)咪唑-2-亚基,L3:N,N-二(4-氯苄基)咪唑-2-亚基];再以咪唑官能团化的N-杂环卡宾配体和氯化镍为原料,通过金属交换反应合成三个新型的镍基双氮杂环卡宾配合物[Ni(NHC)_2]Cl_2(C1~C3),其结构经~1H NMR,IR,元素分析和X-单晶射线衍射表征。配合物C1和C3属于单斜晶系,分别为P2_1/n和P2_1/c空间群。配合物C2属于三斜晶系,为P1空间群。C1~C3的CCDC分别为:1433176,1433177和1433179。     

The role of the solvent in equilibrium and kinetic aspects of metal chelate extractions

Equilibria and kinetics for the extraction of nickel(II) and copper(II) by 2-hydroxy-5-nonylbenzophenone oxime (LIX 65N) in seven organic solvent systems were studied in order to test the validity of several hypotheses related to the role of the solvent in equilibrium and kinetic aspects of metal chelate extraction. For the nickel—LIX 65N system, the extraction constant is essentially independent of the solvent system, whereas for the copper—LIX 65N system, the extraction constant is not independent of solvent; this indicates that while the stoichiometry of the nickel chelate remains the same in all solvents, that of copper does not. The observed rate constant for the nickel—LIX 65N extraction was found to vary inversely with the LIX 65N distribution constant as predicted from a mechanism involving slow formation of the 1:1 complex. The observed reaction rate constant for the copper—LIX 65N varied inversely with the square of the distribution constant, also in accordance with the previously postulated mechanism of the slow formation of the 2:1 copper complex. This study, therefore, unequivocally eliminates the interfacial mechanism in favor of the homogeneous chemical reaction mechanism for the extraction of metal ions by LIX 65N, as well as by other similar high-molecular-weight extractants.     

Kinetics of nickel electroplating from methanesulfonate electrolyte

The overpotential of nickel ion electroreduction on the nickel and mercury electrodes is shown to increase in the following sequence of anions: ClO₄⁻,CH₃SO₃⁻, SO₄²⁻. On the nickel electrode, the overpotential of nickel evolution decreases as the pH^v increases from 1.5 to 4. This is associated with the increase in pH^s as the result of a parallel reaction of hydrogen evolution. It is shown that in contrast to mercury, the Tafel plots of the nickel electrode demonstrate a bend corresponding to the change in their slope from −0.044 to −0.132 V. This is accompanied by the lowering down of the reaction order in nickel ions from 2 to 1. A mechanism of nickel ion electroreduction that includes two parallel routes is proposed and substantiated by a model. In the low overpotential range, the predominant process is the electroreduction of nickel hydroxocomplexes, which is characterized by the strong dependence of the reaction rate on the potential and the concentration of electroactive species. For high overpotentials, the predominant process is the direct discharge of nickel aquacomplexes the rate of which depends weaker on the potential and the concentration of electroactive species.     

Quantum chemical modeling of reaction mechanism for 2-oxoglutarate dependent enzymes: effect of substitution of iron by nickel and cobalt

Enzymatic hydroxylation reactions carried out by 2-oxoglutarate (2OG) dependent iron-containing oxygenases were recently implicated in oxygen sensing. In addition to oxygen depletion, two metals, cobalt and nickel, are capable of inducing hypoxic stress in cells by inhibiting oxygenase activity. Two possible scenarios have been proposed for the explanation of the hypoxic effects of cobalt and nickel: oxidation of enzyme-bound iron following cobalt or nickel exposure, and substitution of iron by cobalt or nickel. Here, by using density functional theory calculations, we modeled the reaction route from the reaction components to the high-spin metal-oxide intermediate in the activation of oxygen molecule by 2OG-dependent enzymes for three metal ions Fe(II), Ni(II), and Co(II) in the active site. An initial molecular model was constructed based on the crystal structure of iron-containing asparaginyl hydroxylase (FIH-1). Nickel- and cobalt-containing enzymes were modeled by a consequent replacement of the iron in the active center. The energy profiles connecting stationary points on the potential surfaces were computed by using the intrinsic reaction coordinate (IRC) technique from the located transition states. The results of calculations show that the substitution of iron by nickel or cobalt modifies the reaction energy profile; however, qualitatively, the reaction mechanism remains essentially the same. Thus, we would postulate that if the iron ion in the active site were substitutable by nickel and/or cobalt ions enzyme activity would be considerably altered due to high activation barriers.     

α‐Diamine Nickel Catalysts with Nonplanar Chelate Rings for Ethylene Polymerization

A series of novel α‐diamine nickel complexes, (ArNH‐C(Me)‐(Me)C‐NHAr)NiBr₂, 1 : Ar=2,6‐diisopropylphenyl, 2 : Ar=2,6‐dimethylphenyl, 3 : Ar=phenyl), have been synthesized and characterized. X‐ray crystallographic analysis showed that the coordination geometry of the α‐diamine nickel complexes is markedly different from conventional α‐diimine nickel complexes, and that the chelate ring (N‐C‐C‐N‐Ni) of the α‐diamine nickel complex is significantly distorted. The α‐diamine nickel catalysts also display different steric effects on ethylene polymerization in comparison to the α‐diimine nickel catalyst. Increasing the steric hindrance of the α‐diamine ligand by substitution of the o‐methyl groups with o‐isopropyl groups leads to decreased polymerization activity and molecular weight; however, catalyst thermal stability is significantly enhanced. Living polymerizations of ethylene can be successfully achieved using 1 /Et₂AlCl at 35 °C or 2 /Et₂AlCl at 0 °C. The bulky α‐diamine nickel catalyst 1 with isopropyl substituents can additionally be used to control the branching topology of the obtained polyethylene at the same level of branching density by tuning the reaction temperature and ethylene pressure.     

A new chemiluminescence method for the determination of nickel ion

A new chemiluminescence (CL) phenomenon described as the second-chemiluminescence (SCL) was observed and a strong CL signal was detected, when Ni(II) ion was injected into the mixture after the end of the reaction of potassium permanganate with alkaline luminol. The possible CL mechanism is proposed based on the kinetic curve of the CL reaction, CL spectra, UV-vis spectra and some other experiments. A flow-injection analysis for the determination of nickle(II) ion has been developed, based on the catalysis of nickel(II) ion on the CL reaction between potassium manganate produced on-line and luminol under alkaline condition. Under the optimum conditions, the SCL intensity is linear with the concentration of nickel(II) ion in the range of 8.0-200.0 microg l-1 and 0.2-2.0 mg l-1. The R.S.D. was 4.5% for 11 determinations of 250 microg l-1 nickel(II) ion and the detection limit (3sigma) for nickel(II) ion was 0.33 microg l-1. The method was applied to determine nickel(II) ion in synthetic samples with satisfactory results.     

Übergangsmetallkomplexe : V. Über eine einfache synthese des phenyl-cyclooctatetraens und dessen liganden-eigenschaften gegenüber nullwertigem nickel

Butyl- and phenylcyclooctatetraene can be prepared in good yield by reaction of 2 equivalents of an organolithium complex with cyclooctatetraene followed by oxidation. In the case of phenylcyclooctatetrane, the intermediate dilithium salt could be isolated. The crystal structures of the 2:1 and 1:1 complexes formed by phenylcyclooctatetraene with zerovalent nickel have been determined by X-ray methods.     

A Study on the Color Reaction of Nickel with a New Chromogenic Reagent 1- (5-Nitro-2-Pyridylazo) - 2.7 - Dihydroxy - naphthalene and its Application

There has been study on heterocyclicazo reagent for the determination of microamount of nickel,but no study on the color reactron of nickel with a new chromogenic reagent 1- (5 -nitro - 2 - pyridylazo) - 2.7 - dihydroxy - naphthalene (5- NO₂ - PADN). So, here is a systematic study on condition under which the color reaction takes place. It proved that within PH 5.5~6.5,the maximnm absotption of the reagent lies at 460nm, that of the 2:1 turquoise chelate by 5 - NO₂ - PADN with nickel (Ⅱ) together is 650nm, and the apparent absorptivity is 1.02×10⁵ L · mol^-1 · cm^-1. The proposed method can be applied in the standard steel and the determination of microamounts of nickel in ore with satisfactory results.     

Nickel‐ and palladium‐catalyzed olefin polymerization under high pressures

The polymerization of 1‐hexene under high pressures (100–750 MPa) was investigated with nickel–α‐diimine complex/methylaluminoxane and palladium–α‐diimine complex/methylaluminoxane as catalyst systems. The catalytic activity of both the nickel and palladium complexes monotonously increased as pressure rose and became two to four times higher than that observed at atmospheric pressure. Palladium catalysts gave poly(1‐hexene)s with higher molecular weights under high pressure, whereas nickel‐catalyzed high‐pressure polymerizations gave polymers with higher molecular weights only at rather low monomer concentrations. The living‐like character in the palladium‐catalyzed polymerizations was somewhat enhanced under higher pressures, whereas the nickel‐catalyzed polymerizations under high pressures were not living. More branches were found in the polymers produced by nickel catalysts at higher pressures. The chain‐transfer reaction seemed to be accelerated by the high pressure in the nickel‐catalyzed reactions, although this was not apparent in the palladium‐catalyzed reactions. Dimers formed and were accompanied by high molecular weight polymers when nickel catalysts were used under high pressures and at high monomer concentrations. The possibility that very congested five‐coordinated species act as key intermediates for the dimerization is discussed. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 293–302, 2003     

Mechanistic studies of the O2-dependent aliphatic carbon-carbon bond cleavage reaction of a nickel enolate complex

The mononuclear nickel(II) enolate complex [(6-Ph(2)TPA)Ni(PhC(O)C(OH)C(O)Ph]ClO(4) (I) was the first reactive model complex for the enzyme/substrate (ES) adduct in nickel(II)-containing acireductone dioxygenases (ARDs) to be reported. In this contribution, the mechanism of its O(2)-dependent aliphatic carbon-carbon bond cleavage reactivity was further investigated. Stopped-flow kinetic studies revealed that the reaction of I with O(2) is second-order overall and is ～80 times slower at 25 °C than the reaction involving the enolate salt [Me(4)N][PhC(O)C(OH)C(O)Ph]. Computational studies of the reaction of the anion [PhC(O)C(OH)C(O)Ph](-) with O(2) support a hydroperoxide mechanism wherein the first step is a redox process that results in the formation of 1,3-diphenylpropanetrione and HOO(-). Independent experiments indicate that the reaction between 1,3-diphenylpropanetrione and HOO(-) results in oxidative aliphatic carbon-carbon bond cleavage and the formation of benzoic acid, benzoate, and CO:CO(2) (～12:1). Experiments in the presence of a nickel(II) complex gave a similar product distribution, albeit benzil [PhC(O)C(O)Ph] is also formed, and the CO:CO(2) ratio is ～1.5:1. The results for the nickel(II)-containing reaction match those found for the reaction of I with O(2) and provide support for a trione/HOO(-) pathway for aliphatic carbon-carbon bond cleavage. Overall, I is a reasonable structural model for the ES adduct formed in the active site of Ni(II)ARD. However, the presence of phenyl appendages at both C(1) and C(3) in the [PhC(O)C(OH)C(O)Ph](-) anion results in a reaction pathway for O(2)-dependent aliphatic carbon-carbon bond cleavage (via a trione intermediate) that differs from that accessible to C(1)-H acireductone species. This study, as the first detailed investigation of the O(2) reactivity of a nickel(II) enolate complex of relevance to Ni(II)ARD, provides insight toward understanding the chemical factors involved in the O(2) reactivity of metal acireductone species.     

近二维结构的六边形金属镍纳米片的水热合成

片状二维镍纳米材料具有较高的形状各异性,在催化、磁记录以及生物探测方面具有重要的应用价值,因此寻找一种简单,成本低的方法制备表面无活性剂的片状镍纳米材料显得尤为重要。在没有有机表面活性剂和形貌控制剂的条件下,在氟掺杂氧化铟锡(FTO)导电玻璃表面,通过水热制备得到金属镍纳米薄片。系统地研究了反应条件对产物形貌的影响,发现镍源、氢氧化钠、氨水的浓度以及反应温度对纳米镍的形貌有较大的影响。只有在合适的氨水和氢氧化钠浓度共同存在下,才能获得具有较大的特征长度以及较薄的近二维结构的六边形镍金属钠米薄片。经过条件优化,制备得到的厚度约为10 nm,横向特征长度超过1μm金属镍纳米薄片。经过分析认为,体系的p H值及温度影响了反应速度,最终导致产物的形貌受到影响,在p H值约为10的条件下,氨水对镍离子的络合作用对镍纳米薄片的二维生长具有一定的促进作用。