Thermal decomposition of Cr(III) dithiocarbamates

The thermal stability of chromium(III) complexes with dithiocarbamate acid derivatives was studied. The general formula of these complexes is (RCS₂)₃Cr where: The thermal stability of these complexes was found to depend on the kind ofR and the decomposition occur in several stages.The final product of the decomposition of the complexes in the 20–600 temperature range investigated is chromium sulphide, Cr₂S₃ or with incomplete combusted sulfur atoms.

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Zusammenfassung Die Thermostabilität von Chrom(III)-Komplexen mit sauren Derivaten von Dithiocarbamat wurde untersucht. Die allgemeine Formel dieser Komplexe ist (RCS₂)₃Cr. Es wurde festgestellt, da\ die Thermostabilität dieser Komplexe von der Art von R abhängt und die Zersetzung in mehreren Stufen verläuft.Das Endprodukt der Zersetzung der Komplexe im untersuchten Temperaturbereich von 20 bis 600 ist Chromsulfid, Cr₂S₃, oder solches mit überschüssigem Schwefel.

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Résumé On a étudié la stabilité thermique des complexes du chrome(III) avec les dérivés de l'acide dithiocarbamique. La formule générale de ces complexes est (RCS₂)₃Cr où: On a trouvé que la stabilité thermique de ces complexes dépendait de la nature du radical et que la décomposition se déroulait en plusieurs étapes.Dans l'intervalle de température étudié, de 20 à 600, le produit final de la décomposition des complexes est le sulfure de chrome, Cr₂S₃, éventuellement accompagné de soufre résultant d'une combustion incomplÊte.

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(III) - . — (RCS₂)₃ Cr, , R . 20–600 Cr₂S₃ .

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The autors would like to thank Doc. dr h. J. F. Biernat for valuable discussions.     

Heterocyclic nickel(II) dithiocarbamates with aromatic thiols as bridging ligands

Binuclear NiII dithiocarbamates, with aromatic monothiols as bridging ligands, of composition [Ni(-L) (Rdtc)]2 [dtc = S2CN, R = C4H8O (morph), C5H10 (pip), C4H8 (pld); HL = thiophenol, 4-methylthiophenol or 2-thionaphthol] and [Ni(-L)(HR1dtc)]2 {R1 = C11H11N2O (aap)} have been prepared and characterized by elemental analyses, i.r. and electron spectroscopy, magnetochemical and conductivity measurements, and thermal analysis. The methods used indicate that the complexes are diamagnetic, complex non-electrolytes with two square-planar NiS4 chromophores.     

Four types of relaxation in chemical kinetics (linear case)

According to results obtained previously for the linear equations of chemical kinetics, the relation between the steady-state reaction rate and the relaxation time has been studied.

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, , .

     

Heterogeneous reactions of solid nickel(II) complexes

The influence of different modes of preparation on the stoichiometry of thermal decomposition of isothiocyanatonickel(II) complexes with ammonia was studied. It was found that the complex Ni(NCS)₂(NH₃)₄ (I) prepared by heterogeneous reaction undergoes decomposition in two steps (–2 NH₃, –2 NH₃), while for complex II, of the same composition but prepared by homogeneous reaction from solution, the decomposition proceeds in three steps (–1 NH₃, –1 NH₃, –2NH₃). Electronic and infrared absorption spectra were used for the study of the spectral properties of the starting complex. It was found that the different stoichiometries of thermal decompositions of complexes I and II do not cause differences in the bonding strength of the ammonia molecules (chemical factor); this effect is rather brought about by physical factors such as different imperfections of the crystal lattice.

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Zusammenfassung Der Einfluß der Herstellung auf die Stöchiometrie der thermischen Zersetzung von Amin-Komplexen des Isothiocyanatonickels wurde studiert. Der Zerfall des Komplexes Ni(NCS)₂(NH₃)₄ (I), hergestellt durch heterogene Reaktion, verlief in zwei Etappen (–2 NH₃, –2 NH₃). Beim selben Komplex (II), hergestellt durch homogene Reaktion in Lösung, wurden jedoch drei Etappen beobachtet (–1 NH₃, –1 NH₃, –2 NH₃). Die Eigenschaften des Ausgangsproduktes wurden durch Elektronen- und IR-Spektroskopie untersucht. Das unterschiedliche thermische Verhalten ist nicht auf eine verschiedene Bindungsstärke der NH₃ Moleküle, sondern auf physikalische Ursachen, wie z. B. Unregelmässigkeiten im Kristallgitter zurückzuführen.

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Résumé On a étudié l'influence des diverses méthodes de préparation sur la stoechiométrie de la réaction de décomposition thermique des complexes de l'isothiocyanate de nickel(II) avec l'ammoniac. On a établi que le complexe Ni(SCN)₂(NH₃)₄, (I), préparé rar réaction hétérogène, subit une décomposition en deux étapes (–2NH₃, –2NH₃), tandis que le complexe (II), de même composition, mais préparé par réaction homogène, à partir de solutions, se décompose en trois étapes (–1NH₃,–1NH₃, –2NH₃). Les propriétés spectrales du complexe initial ont été étudiées par absorption électronique et infrarouge. On a trouvé que les différences de stoechiométrie des réactions de décomposition thermique des complexes (I) et (II) n'apportaient pas de différences entre les énergies de liaison des molécules d'ammoniac (facteur chimique). C'est plutôt à des facteurs physiques, comme les différentes imperfections du réseau cristallin, que cet effet serait dû.

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(II) . , Ni(NCS)₂(NH₃)₄ (I), , (–2NH₃,–2NH₃). , II , , (–1 NH₃,–1 NH₃ –2NH₃). . , I II ( ), , .

     

Thermal properties of thio-and selenocyanatocopper(II) complexes with bipyridine and phenanthroline

The paper deals with the thermal properties of complex compounds of the general formula CuL₂(NCX)₂ (whereL=bipy or phen,X=S or Se). The phenanthroline complexes exhibit a higher thermal stability than those with bipyridine. For the latter complexes thermal decomposition begins with the release of bipyridine molecules, while for the phenanthroline complexes redox reactions of pseudohalogenide ligands with Cu(II) take place. The redox reactions start at a lower temperature for the selenocyanate complexes than for the thiocyanate complexes.

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Zusammenfassung Vorliegende Arbeit behandelt die thermischen Eigenschaften von Komplexverbindungen der allgemeinen Formel CuL₂(NCX)₂ (mitL=Bipyridin oder Phenanthrolin undX=S oder Se). Die Phenanthrolinkomplexe zeigen eine grössere thermische Stabilität als die Bipyridinkomplexe. Die thermiscne Zersetzung letzterer beginnt mit der Abgabe von Bipyridinmolekülen, während bei den Phenanthrolinkomplexen Redoxreaktionen von Pseudohalogenidliganden·mit Cu(II) stattfinden. Diese Redoxreaktionen beginnen bei den Selenozyanatkomplexen bei niedrigeren Temperaturen als bei den Thiozyanatkomplexen.

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CuL₂(NCX)₂, L= , X= . . , — . - , .

     

Mono and dinuclear cationic rhodium(I) and iridium(I) complexes with sulphur donor and group Vb ligands

Summary Rhodium(I) and iridium(I) mixed complexes of the formulae [M(diolefin)LL]ClO₄, [M(diolefin)L₂L]ClO₄, [(diolefin)LIr(-L)₂IrL(diolefin)](ClO₄)₂, [(diolefin)LM(-L-L)ML'(diolefin)](ClO₄)₂, [(diolefin)Rh{-(L-L)}₂Rh(PPh₃)₂](ClO₄)₂ and [(diolefin)LIr{-(L-L)}₂IrL (diolefin)](C1O₄)₂, (L=monodentate sulphur ligand, L-L=bidentate sulphur ligand, L=group Vb ligand; M=Rh, diolefin=1,5-cyclooctadiene (COD) or 2,5-norbornadiene (NBD); M=Ir, diolefin=COD) are described.Author to whom all correspondence should be directed.     

Hydrogenation of carbon monoxide catalysts prepared by pyrolysis of Co2(CO)8 on various oxide supports

Catalysts prepared by pyrolysis of Co₂(CO)₈ on oxide supports have been studied in the hydrogenation of CO. It is shown that MgO and -Al₂O₃-based catalysts are less active than those supported on SiO₂, TiO₂ and ZrO₂. The application of -Al₂O₃ as a support increases the relative yield of light hydrocarbons.

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, Co₂(CO)₈ , CO. , MgO -Al₂O₃ SiO₂, TiO₂ ZrO₂. -Al₂O₃ .

     

Nickel(II) xanthates with nitrogen heterocycles as bridging ligands

New homopolynuclear nickel(II) xanthate complexes with nitrogen donor heterocycles as bridging ligands have been prepared, namely [Ni(Rxa)2(-L)]n and [Ni2(Rxa)4(-L1)], where R=i-Pr,i-Am; xa=OCS2– L=1,2-bis(4- pyridyl)ethane (bpe), 4,4-dithiodipyridyl (dtp), 1,2-bis(4- pyridyl)ethylene (dpe), 4,4-trimethylene-dipyridine (tmd); L1=2,3-bis(2-pyridyl)pyrazine (bpp), 2,4-bis(5,6- diphenyl-1,2,4-triazine-3-yl)pyridine (bdt), or 2,4,6-tris(2- pyridyl)-1,3,5-triazine (tpt). The compounds have been characterized by elemental analyses, i.r. and electronic spectroscopies, magnetochemical and conductivity measurements. The results show that the [Ni(Rxa)2(-L)]n complexes are linear polymers in which the nitrogen heterocycles bridge between the nickel(II) ions, which are coordinated by four sulfur and two nitrogen atoms and have trans-octahedral geometry. The nearly constant values of the effective magnetic moment (3.36–3.34 eff/B) over the 77–295 K temperature range indicate that exchange interactions are lacking among the paramagnetic centres in the linear structure, [Ni(i-Amxa)2(dpe)]n. The variable- temperature magnetic susceptibilities of the [Ni2(i-Prxa)4(bpp)] (3.00–2.95eff/B per Ni atom), [Ni2(i-Prxa)4(bdt)] (2.72–2.63 eff/B per Ni atom), and [Ni2(i-Amxa)4(tpt)] (2.76–1.87 eff/B per Ni atom) were measured down to liquid nitrogen temperature. In the case of binuclear nickel(II) complexes with bdt or tpt, antiferromagnetic coupling between the nickel(II) ions was detected, giving the exchange integral J=–4.0cm–1 and –29.6cm–1, respectively.     

Kinetics of Cr(VI) and V(V) oxidation of trans-stilbene and indene

Title reactions are acid catalyzed and strongly dependent on the permittivity of the medium. With Cr(VI) indene reacts faster than trans-stilbene, but with V(V), trans-stilbene reacts faster than indene. The mechanism is discussed.

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. Cr(VI) , -, V(V) - , . , .

     

Temperature programmed reduction and oxidation of Ir/Al2O3 catalysts

3 % Ir/Al₂O₃ catalysts have been studied by means of temperature programmed reduction and oxidation. With growing degree of metal oxidation (higher T_ox) reducibility of the catalysts at low temperatures decreases.

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3% Ir/Al₂O₃ . ( ) .

     

Thermogravimetry of copper and copper oxides (Cu2O-CuO)

The thermogravimetry of mixtures of metallic copper and copper oxides was studied. The experiments were performed by heating the samples in air to 700–800° to transform all the components to copper(II) oxide, and continuing the heating in nitrogen to 1050–1100° when the dissociation of copper(II) oxide to copper(I) oxide is complete. The identification of the components and their quantitative determination were carried out by determining the shape, size, and ratio of the segments of the curves obtained during the heating. The method can be used for quantitative analysis of mixtures of copper and/or copper oxides.

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Zusammenfassung Gemische von metallischem Kupfer und Kupferoxiden wurden thermogravimetrisch untersucht. Zur Überführung aller Komponenten in Kupfer(II)-oxid erhitzte man sie in Luft auf 700–800°, um daraufhin bis zur vollständigen Dissoziation des Kupfer-(II)-oxids zu Kupfer(I)-oxid unter Stickstoff die Temperatur bis auf 1050–1100° zu steigern. Die Identifizierung der Komponenten und ihre quantitative Bestimmung erfolgten durch die Form, Größe und die Verhältnisse der verschiedenen Abschnitte der erhaltenen Kurven. Diese Methode ist zur quantitativen Bestimmung von Gemischen aus Kupfer und Kupferoxid sowie von Kupferoxiden geeignet.

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Résumé Étude thermogravimétrique de mélanges du cuivre métallique et d'oxydes de cuivre. Les échantillons sont d'abord chauffés dans l'air jusqu'à 700–800° jusqu'à ce que tous les constituants soient transformés en oxyde de cuivre(II); le chauffage est ensuite poursuivi dans l'azote jusqu'à 1010–1100°, où la dissociation de l'oxyde de cuivre(II) en oxyde de cuivre(I) est complète. Les constituants ont été identifiés et dosés en utilisant la forme, la dimension et les proportions des différentes parties des courbes pendant le chauffage. La méthode peut être utilisée pour l'analyse quantitative de mélanges de cuivre et ou d'oxydes de cuivre.

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. 700–800: ( (), 1050–1100° [ () (I)]. , , . / .

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The author wishes to acknowledge the financial assistance provided by the Technion — Israel Institute of Technology.The author wishes also to thank Dr. R. F. Tylecote (University of Newcastle Upon Tyne, England) for very helpful comments and useful discussions of this investigation and to Mrs. N. Leder for chemical analyses.     

Differential thermal analysis of poly(vinylidene chloride) crystals

The melting behavior of poly(vinylidene chloride) (PVDC) was studied using differential thermal analysis (DTA). Crystals were grown isothermally from 0.1% and 0.02% dilute solutions of the polymer in 1.2-dibromoethane and monobromobenzene. Both solid and oil samples were used for the DTA experiments. Solid samples are defined as dried down crystals and oil samples are crystals which have been suspension exchanged in silicone oil without letting them dry out. Thermal curves of solid samples are similar to those obtained previously with as-polymerized crystals, that is they show two endotherms. The lower temperature peak corresponds to the melting of lamellae as formed. The upper peak at around 200°C, may be due to the melting of crystals which have reorganized during heating. Thermal curves of oil samples show two extra small peaks in addition to those of the solid samples. From the results of annealing and degradation experiments, these two peaks may correspond to a small portion of the crystals which have been partially degraded to form double bonds and thus possess lower melting points. An alternative explanation is that there is an as yet unreported second crystal form of PVDC.

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Zusammenfassung Das Schmelzverhalten von Poly/vinylidenchlorid (PVDC) wurde unter Einsatz der Differentialthermoanalyse (DTA) untersucht. Die Kristalle wurden unter isothermen Bedingungen aus 0.1 % und 0.02% verdünnten Lösungen des Polymeren in 1.2-Dibromäthan und Monobrombenzol gezüchtet. Sowohl »feste« als auch »ölige« Proben wurden für die DTA-Versuche eingesetzt. Als »feste« Proben wurden getrocknete Kristalle definiert und »ölige« als solche, bei welchen die Suspension im Siliconöl verblieb, ohne sie austrocknen zu lassen. Die thermische Kurven der »festen« Proben sind den bereits früher mit polymerisierten Kristallen erhaltenen ähnlich, d. h. sie zeigen zwei Endotherme. Der Peak bei der niedrigeren Temperatur entspricht den Schmelzen der gebildeten Lamellen. Der obere Peak bei etwa 200° kann dem Schmelzen von während der Aufheizung reorganisierten Kristallen zugeschrieben werden. Die thermische Kurven der »öligen« Proben zeigen zwei zusätzliche kleine Peaks außer denen an »festen« Proben. Aus den Ergebnissen der Temper- und Zersetzungsversuche dürften diese beiden Peaks einen kleinen Anteil der teilweise unter Bildung von Doppelbindungen zersetzten Kristalle entsprechen, welche auf diese Weise niedrigere Schemlzpunkte haben. Eine alternative Erklärung ist, daß es eine bisher nicht beschriebene zweite Kristallform von PVDC gibt.

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() . ( 0.1% 0.02%) 1.2- . «» « » . « » , — , , . - «» . . 200° , . « » , , . , , , . . , .

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The authors wish to thank the NSF Materials Division for support of this work under grants DMR 72-03292 A01 and A02.     

Quasi-homeopolar states in conjugated hydrocarbons. Interaction of π- and σ-electrons

Quasi-homeopolar levels of - and -electrons in conjugate hydrocarbons are considered. It is shown that in the spin hamiltonian and the projected operators of the physical values there appear terms which involve --interaction. The spin hamiltonian of --interaction is small, and its contribution to energies and spin functions can be calculated from perturbation theory by taking the spin hamiltonian of noninteracting - and -electrons as equal to zero. The - and -electrons of the C=C bond in ethylene are considered in detail. Calculations show that their interaction increases the excitation energy of the lower triplet of ethylene. The spin hamiltonian parameters of the simplest conjugate hydrocarbons are determined.The accuracy of the valence-bond method is investigated on the basis of the theory of quasi-homeopolar levels. It is shown that empirical selection of the parameters partially compensates for the errors which are made in the derivation of the fundamental equation for this approximation.     

Oxidation of aroyl hydrazines, III. Kinetics and mechanism of the oxidation of nicotinoyl and isonicotinoyl hydrazine by iodine

The title reaction was studied in aqueous hydrochloric acid at high iodide concentations. The reaction is first order with respect to both oxidant and substrate though diisonicotinoyl hydrazines are the products apart from nitrogen. The reaction is markedly inhibited by H⁺ and I^– ions. An I^– ion independent path is also noticed.

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. , , -() , . H⁺ I^–. , , I^–.

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Part II: Indian J. Chem. (In press)     

The thermal decomposition reactions of bis-(pyridine-2-aldoxime)-copper(II) complexes

The thermal properties of some complexes of copper(II) with pyridine-2-aldoxime (HPAO), where the ligand appears either as the ion (PAO^–) or as a neutral molecule, were determined in vacuo and in dynamic nitrogen and oxygen gas atmospheres. The study was carried out by thermoanalytical (TG, DTG. DTA), spectroscopic and spectrometric (UV-visible, IR, diffuse reflectance, mass) techniques.The initial decomposition temperature is influenced by the number of acid hydrogens in the complex; the thermal stability sequence in vacuo is: [Cu(PAO)₂H]Cl > [Cu(PAO)₂H₂]Cl₂ > [Cu(PAO)₂]The thermal decomposition reactions occur in several separate steps, the first of which gives rise to partial ligand decomposition, the reduction of copper(II) to copper(I), and the conversion of the residual pyridine-2-aldoxime into acid amide.

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Zusammenfassung Die thermischen Eigenschaften einiger Komplexe von Kupfer(II) mit Pyridin-2-aldoxim (HPAO), in denen der Ligand entweder als Ion (PAO^–) oder als neutrales Molekül vorliegt, wurden im Vakuum und in dynamischer N₂- und O₂-Atmosphäre ermittelt. Zur Untersuchung wurden thermoanalytische (TG, DTG, DTA) und spektrometrische (UV-sichtbar, IR, diffuse Reflektionsspektrophotometrie, Massenspektrometrie) Techniken herangezogen. Die Temperatur, bei der die Zersetzung beginnt, wird durch die Zahl der sauren Wasserstoffatome im Komplex beeinflußt; für die thermische Stabilität im Vakuum gilt die Reihenfolge [Cu(PAO)₂H]Cl > [Cu(PAO)₂H₂]Cl₂ > [Cu(PAO)₂]. Die thermischen Zersetzurigsreaktionen verlaufen in mehreren diskreten Schritten, wobei der erste von diesen eine partielle Zersetzung des Liganden, die Reduktion von Kupfer(II) zu Kupfer(I) und die Konversion des verbleibenden Pyridin-2-aldoxims in das Säureamid in sich einschließt.

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-2- ( ), (-), . (, , ) , - , , - . , [Cu(PAO)₂H]CI > [Cu(PAO)₂H₂]Cl₂ > [Cu(PAO)₂] , , -2- .

     

On the relationship between the structures of Cu(II) complexes and their chemical transformations

The paper deals with the relationship between the crystal and molecular structures of CuSO₄.5 H₂O, CuSO₄.3 H₂O and CuSO₄.H₂O on the one hand, and the stoichiometries of their thermal decompositions on the other. With the use of methods of X ray powder diffractograms, i.r. and electronic spectra, evidence is provided that the intermediates of the thermal decomposition of CuSO₄.5 H₂O have the same crystal and molecular structures as CuSO₄.3 H₂O and CuSO₄.H₂O prepared by other procedures. It is also shown that at temperatures near that of the thermal decomposition, certain, not further identified structural changes take place in CuSO₄.5 H₂O.

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Zusammenfassung Es wird einerseits der Zusammenhang der Kristall- und Molekularstruktur von CuSO₄ · 5H₂O, CuSO₄ · 3H₂O und CuSO₄ · H₂O behandelt und andererseits die Stöchiometrie ihrer thermischen Zersetzung. Mit der Auswertung der Röntgen-Pulverdiffraktogramme, der IR- und Elektronenspektren wurde der Beweis erbacht, da\ die Zwischen-produkte der thermischen Zersetzung von CuSO₄ · 5H₂O dieselben Kristall- und Molekül-strukturen besitzen, wie auf anderen Wegen hergestelltes CuSO₄ · 3H₂O bzw. CuSO₄ · H₂O. Ferner wurde gezeigt, da\ bei Temperaturen in der NÄhe der thermischen Zersetzungstemperatur gewisse, jedoch noch nicht identifizierte StrukturÄnderungen in dem CuSO₄ · 5H₂O stattfinden.

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Résumé L'article examine la corrélation entre les structures cristallines et moléculaires de CuSO₄.5 H₂O, CuSO₄.3 H₂O et CuSO₄.H₂O d'une part et la stoechiométrie de leur décomposition thermique de l'autre. En se servant des méthodes des diffraction des rayons X sur poudre et des spectres infra-rouges et électroniques on montre que les produits intermédiaires de la décomposition thermique de CuSO₄.5 H₂O ont les mÊmes structures cristallines et moléculaires que celles de CuSO₄.3 H₂O et de CuSO₄.H₂O préparées par d'autres procédés. On montre également qu'à des températures proches de celle de la décomposition thermique de CuSO₄. 5H₂O des changements structuraux non encore identifiés ont lieu.

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uSO₄ · 5₂, uSO₄ · ₂ uSO₄ · ₂, — . , , , uSO₄ · 5₂ uSO₄ · ₂ uSO₄ · ₂, . , , uSO₄, · 5₂ , .

     

Simultaneous determination of cobalt,nickel and iron by multi-wavelength spectrophotometry

A method for the simultaneous spectrophotometric determination of cobalt, nickel and iron based on the formation of their complexes with 1,5-bis(di-2-pyridylmethylene) thiocarbonohydrazide is proposed. The absorption curves of these complexes overlap severely in the scanning range 390–510 nm. The analyte concentrations are calculated by a least squares fit of the pure spectra to the mixture spectra, which therefore makes the simultaneous determination of these metallic ions possible without tedious pretreatment. The detection limits afforded by the proposed method range from 0.05 g/ml for Fe and Ni to 0.1 g/ml for Co. Root-mean-squared errors of prediction of 0.085 g/ml for Co, 0.048 g/ml for Ni and 0.1172 g/ml for Fe were obtained using the wavelength range 400–510 nm and 0.147 g/ml for Co, 0.107 g/ml for Ni and 0.127 g/ml for Fe using the wavelength range 420–434 nm. The effect of interferences is studied and the proposed method is applied to analysis for the above elements in synthetic samples and real samples, such as biological materials and alloys.     

Reduction kinetics of Mo/Al2O3 catalysts

Studies of the reduction kinetics of MoO₃ and Al₂O₃–MoO₃ catalysts in H₂ at 523–823 K indicate that molybdenum is present in Al₂O₃/MoO₃ in three forms: as Mo⁶⁺ in the Al₂O₃ lattice and as MoO₃ and Al₂(MoO₄)₃ phases. Activation energies of reduction E_act determined according to the Avrahmy-Erofeev equation, are reported.

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MoO₃ Al₂O₃–MoO₃ H₂ 523–823 . Al₂O₃–MoO₃ : Mo⁶⁺ Al₂O₃ MoO₃ Al₂(MoO₄)₃, . -.

     

New Molybdenum(V) Complexes Prepared by the Oxidation of Dinuclear Quadruply-Bonded Molybdenum(II) Monothiocarboxylates

Oxidation of molybdenum(II) thiopivalate and thiobenzoate in the presence of -picoline or pyridine results in the formation of dinuclear molybdenum(V) complexes of the general formulae [Mo₂O₂(-O)₂(-SO₄)L₄] with L = -picoline or pyridine and [Mo₂O₂(-O)(-S)(-SO₄)L₄] with L = -picoline. As determined by X-ray structure analysis, two complexes with -picoline differ in their bridging cores: In one complex, two Mo atoms are doubly bridged through two oxygen atoms; in the other, one Mo atom is doubly bridged through oxygen and sulfur atoms. However, they both crystallize together. The product is solvated with -picoline and water molecules. Molybdenum atoms exhibit distorted octahedral coordinations. The same complexes were prepared also through direct reactions of [Mo₂O₃(O₂CCH₃)₄] with thiopivalic and thiobenzoic acid in the presence of -picoline or pyridine. The appearance of the oxo-oxygens and sulfido-sulfur as well as sulfato ligand is explained by the molybdenum-catalyzed oxidation of thiocarboxylates.     

Thermal and some other properties of the complexes crystallizing from the system Ni(II)-en-[Ni(CN)4]2−-H2O

Seven complex compounds exhibiting the compositions Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) and-Ni(en)₂Ni(CN)₄ (VII) were prepared from the system Ni-en-[Ni(CN)₄]^2–-H₂O. These compounds were examined by the methods of infrared spectroscopy, X-ray powder diffractometry, UV-VIS reflectance spectroscopy, and also by the measurement of magnetic moments. The thermal stability, the stoichiometry of thermal decomposition and the mutual transformations were investigated with a derivatograph. The reactions proceeding according to the following schemes were observed if the system was heated to appropriate temperature: (I)(II)(III)(V)(IV) and (VI)(VII)(III)(V)(IV) Process (VII)(III) represents isomerization. The reversibility of the process (V)(IV) is due to the high hygroscopicity of the anhydrous complex. The changes in structure in the course of the individual processes are discussed.

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Zusammenfassung Aus einem System Ni-en-[Ni(CN)₄]^2–-H₂O wurden sieben Komplexe der Formeln Ni(en)₃Ni(CN)₄·H₂O (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄·2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2.5H₂O (VI) und-Ni(en)₂Ni(CN)₄ (VII) hergestellt. Diese Verbindungen wurden mittels IR-Spektroskopie, Röntgenpulverdiffraktometrie, UV-Reflexionsspektroskopie und durch Messungen des magnetischen Momentes untersucht. Die Wärmestabilität, die Stöchiometrie des thermischen Zerfalles und die gegenseitigen Umwandlungen wurden mittels eines Derivatographen untersucht. Wird das System auf geeignete Temperaturen erhitzt, kann der Reaktionsverlauf durch folgendes Schema dargestellt werden: (I)(II)(III)(V)(IV) und (VI)(VII)(III)(V)(IV).Der Prozeß (VII)(III) verkörpert eine Isomerisierung. Die Umkehrbarkeit von Prozeß (V)(IV) ist auf die ausgeprägten Hygroskopieeigenschaften des wasserfreien Komplexes zurückzuführen. Es werden die im Ablaufe der einzelnen Prozesse vorgehenden Strukturveränderungen besprochen.

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Ni- -[No(N)]² -₂ Ni(en)₃Ni(CN)₄ · ₂ (I), Ni(en)₃Ni(CN)₄ (II),-Ni(en)₂Ni(CN)₄ (III), Ni(en)Ni(CN)₄-2H₂O (IV), Ni(en)Ni(CN)₄ (V), Ni(en)₂Ni(CN)₄ · 2,5H₂O (VI) -Ni(en)₂Ni(CN)₄ (VII). , , - , . , . (I)(II)(III)(V)(IV) (VI)(VII)(III)(V)(IV). (VII)(III) . (V)(IV) . .