Thermal decompositions of some transition metal polyacrylates

Polyacrylales of Fe, Cr, Ni, Co and Mn were synthesized by the reaction of poly(sodium)acrylatc with metal halides. The salts obtained were investigated by thermal analysis. During heating in argon or air, all the salts behaved in a similar way. The initial decomposition temperature of the investigated salts increased in the following sequence: Fe<Cr<Ni<Co<Mn. The solid residues of the decompositions of the salts were also analysed.

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Zusammenfassung Polyacrylate von Fe, Cr, Ni, Co und Mn wurden durch Reaktion von Natriumpolyacrylat mit den entsprechenden Metallhaliden synthetisiert. Die erhaltenen Salze wurden thermoanalytisch untersucht. Beim Aufheizen in Argon und Luft verhalten sich alle Salze ähnlich. Die Temperatur, bei der die Zersetzung einsetzt, steigt in folgender Reihenfolge an: Fe < Cr < Ni < Co < Mn. Die festen Rückstände der Zersetzung der Salze wurden ebenfalls analysiert.

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, , , . , , . Fe<Cr<Ni<Co<Mn. .

     

Thermal decompositions of some divalent transition metal complexes of triethanolamine

The thermal behaviours of the Ti(II), Mn(II), Fe(II), Ni(II), Cu(II) and Zn(II) complexes of triethanolamine were studied by means of thermogravimetry, differential thermogravimetry, differential thermal analysis infrared spectrophotometry and elemental analysis. The sequence of thermal stability of the metal complexes, determined by using the initial decomposition temperature, was found to be Ti(II)?Mn(II)>Fe(II)>Ni(II)>Zn(II)>Cu(II). Some of the kinetic parameters, such as the activation energy and order of reaction for the initial decomposition reaction, were calculated and the relationship between the thermal stability and the chemical structure of the complexes is discussed.     

Study of the thermal decompositions of some transition metal perchlorates

The thermal decompositions of nickel(II), copper(II), cobalt(II) and manganese(II) perchlorates were studied by thermal analysis and kinetic measurements. Anhydrous perchlorates could not be prepared by heating and outgassing the samples in vacuum; oxides were obtained as the main solid decomposition products. In the case of cobalt and manganese perchlorates, oxidation of the metal ions was observed during the decomposition. In most cases the decompositions of the perchlorates followed the Avrami-Erofeyev kinetics. A correlation was found between the stabilities of the perchlorates and the effective field strengths of the cations.

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Zusammenfassung Die thermische Zersetzung von Nickel(II), Kupfer(II)-, Kobalt(II)- und Mangan(II)-perchloraten wurde mittels Thermoanalyse und kinetischer Messungen untersucht. Durch Erhitzen und Entgasen der Proben im Vakuum konnten keine wasserfreien Perchlorate hergestellt werden; Oxide wurden als feste Hauptzersetzungsprodukte erhalten. Im Falle der Perchlorate von Kobalt und Mangan wurde die Oxidation der Metallionen während der Zersetzung beobachtet. In den meisten Fällen verlief die Zersetzung der Perchlorate nach der Kinetik von Avrami-Erofeyev. Eine Korrelation wurde zwischen den Stabilitäten der Perchlorate und der tatsächlichen Feldstärke der Kationen gefunden.

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Résumé La décomposition thermique des perchloartes de nickel(II), de cuivre(II), cobalt(II) et de manganèse(II) a été étudiée par analyse thermique et mesures cinétiques. Les perchlorates anhydres n'ont pas pu être préparés par chauffage et traitement sous vide de échantillons; les oxydes ont été obtenus comme produits solides principaux de décomposition. Dans le cas des perchlorates de cobalt et de manganèse, l'oxydation des ions métalliques a été observée pendant la décomposition. Dans la plupart des cas, la décomposition des perchlorates a suivi la cinétique d'Avrami-Erofeyev. Une corrélation a été trouvée entre la stabilité des perchlorates et les intensités effectives des champs des cations.

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The thermal decompositions of some transition metal acrylates and polyacrylates

The thermal behaviours of zinc, cobalt, nickel and copper acrylates and their polymers were investigated. It was found that the decompositions of these compounds are complex processes. The main decomposition of the monomer was preceded by thermal polymerization. The thermal effect of this reaction was greater for zinc acrylate than for the other salts. The reaction orders and activation energies of decomposition of the monomers and the polymers were calculated and the differences discussed.

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Zusammenfassung Das thermische Verhalten der Acrylate von Zink, Kobalt, Nickel und Kupfer und das der entsprechenden Polymere wurde untersucht. Es wurde festgestellt, dass die Zersetzung dieser Verbindungen komplexe Prozesse sind.Der Zersetzung der Monomeren ging eine thermische Polymerisation voraus. Der thermische Effekt dieser Reaktion war im Falle des Zinkacrylats grösser als bei den anderen Salzen. Die Reaktionsordnungen und Aktivierungsenergien der Zersetzung der Monomeren und Polymeren wurden berechnet und die Unterschiede diskutiert.

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Solid state decomposition studies on metal salicylates: Kinetics of iso-thermal dehydration of some transition metal salicylato complexes

The dehydration of cadmium(II ) , copper(II), manganese(II), nickel(II) and zinc(II) salicylato complexes were investigated by means of isothermal TG measurements. The Cd, Mn and Zn complexes were dihydrates. Ni complex was a tetrahydrate while Cu formed both dihydrate and tetrahydrate complexes. Thermal decomposition of the studied complexes synthesized using a pure salicylic acid as a ligand occurs in three stages, the oxides finally being formed. The first step being associated to the dehydration of the complexes obeys a phase boundary reaction mechanism. The ΔH values for hydration of Cd, Cu, Mn and Zn dihydrate complexes are 116.5, 76.0, 86.8, 113.3 kJ mol⁻¹ and for Cu and Ni tetrahydrates 117.1 and 108.9 kJ mol⁻¹, respectively.     

Thermal decomposition of some heavy and transition metal benzenesulphonates

The thermal behaviours of Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II), Pb(II), and VO(II) benzenesulphonates were studied by simultaneous thermoanalytical methods (DTA, TG, DTG, EGA). The measurements were at times supplemented by X-ray analysis of the decomposition products, as well as by chemical analysis. The decomposition processes of samples were carried out in oxygen, in air and in nitrogen atmospheres. The effect of the atmosphere on the decomposition was studied primarily with regard to the reaction paths of the sulphur content of compounds investigated. The possibility of quantitative analysis of these salts was studied from the aspects of both residues and the sulphur oxide products.

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Zusammenfassung Das thermische Verhalten von Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II), Pb(II) und VO(II)-benzolsulfonaten wurde durch simultane thermoanalytische Methoden (DTA, TG, DTG, EGA) untersucht. Gelegentlich wurden die Messungen durch Röntgenanalyse der Zersetzungsprodukte sowie durch chemische Analyse ergänzt. Die Zersetzungsvorgänge der Proben wurden in Sauerstoff, Luft und Stickstoffatmosphäre durchgeführt. Die Wirkung der Atmosphäre auf die Zersetzung wurde untersucht, mit besonderer Berücksichtigung der Reaktionen entsprechend dem Schwefelgehalt der geprüften Verbindungen. Die Möglichkeit der quantitativen Analyse dieser Salze wurde nach den Resten und den Schwefeloxid-Produkten untersucht.

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Résumé On a étudié par ATD, TG, TGD et AGE simultanées le comportement thermique des benzène-sulfonates de Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II), Pb(II) et VO(II). Occasionnellement, on a complété ces résultats par analyse aux rayons X et par analyse chimique. On a étudié l'effet de l'atmosphère (oxygène, air et azote) sur la décomposition, surtout du point de vue des processus réactionnels liés à la teneur en soufre des composés. On a étudié la possibilité d'une analyse quantitatitive de ces sels à partir des résidus ainsi qu'à partir des oxydes de soufre.

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- Mn(II), Fe(II), Fe(III), Co(II), Ni(II), Cu(II), Zn(II), Ag(I), Cd(II),Pb(II)VO(II) (, , ). , . , . . , .

     

Solid state decomposition studies on metal salicylates. Thermal decomposition of some lanthanide salicylato complexes

The thermal stability and mechanism of thermal decomposition in air of the four lanthanide complexes of 2-hydroxybenzoic acid have been studied by TG, DSC, IR and MS techniques. An analysis of the prepared compounds show that Pr(III), Nd(III) and Tb(III) form anhydrous salicylato (Hsal)⁻ complexes while the corresponding holmium compound contains four water molecules. The TG curves show two (praseodymium, terbium), three (neodymium) or four (holmium) main stages of thermal decomposition. The most unstable among the complexes studied is Ho(Hsal)₃·4H₂O which releases four water molecules in an endothermic dehydration step. Ligand molecules decompose mainly in two stages of which the first is endothermic and is attributed to the release of the ligand acid and the second is a strongly exothermic decarboxylation process. The final decomposition product is the corresponding lanthanide(III) oxide, except in the case of terbium which decomposes to Tb₄O₇.     

Thermal studies on 2,6-xylyliminodiacetato compounds of some transition metal ions

Some new 2,6-xylyliminodiacetato compounds of Mn(II), Fe(III), Ni(III), Zn(II) and Cd(II) have been prepared in aqueous media. The thermal behaviour of these compounds has been studied by TG, DTG, and DSC techniques. Heats of dehydration have been calculated from the DSC curves.     

Thermal decompositions of complexes of metal ions with riboflavin

Two kinds of complexes of riboflavin with Zn(II), Co(II), Cu(II), Fe(III), Mg(II) and Ca(II) were synthesized, having metal: ligand molar ratios of 11 and 21. When heated, these complexes first lose water. Their thermal degradation in static air atmosphere starts at temperatures higher than, equal to, or lower than that observed for free riboflavin degradation. The rates and stages of pyrolysis were related to the structures of the complexes.

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Zusammenfassung Es wurden zwei verschiedenartige Komplexe von Riboflavin mit Zn(II), Co(II), Cu(II), Fe(III), Mg(II) und Ca(II) mit einem molaren Metall-Ligandenverhältnis von 11 und 21 dargestellt. Beim Erhitzen geben diese Komplexe zuerst Wasser ab. Ihre thermische Zersetzung beginnt in unbewegter Luftathmosphäre bei einer Temperatur, die entweder mit der für die Zersetzung freien Riboflavins übereinstimmt, größer oder kleiner als diese ist. Die Abschnitte und Geschwindigkeit der Pyrolyse werden mittels der Struktur der Komplexe erläutert.

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, , , : 11 21. . , . .

     

The preparations and decompositions of some chloroacetyl-transition metal derivatives

The reactions of ClCH₂COCl with NaM(CO)₃C₅H₅ (M = Cr, Mo, W), NaM′(CO)₅ M′ = Mn, Re), NaFe(CO)₂C₅H₅, (Ph₃P)₄Pt and Cl(CO)(Ph₃P)₂Ir were examined. The chloroacetylmetal derivatives, C₅H₅(CO)₃MCOCH₂Cl (M = Mo, W), C₅H₅(CO)₂FeCOCH₂Cl, and (CO)₅MnCOCH₂Cl, were isolated and their thermal and photochemical decompositions studied. The last complex decomposes to produce Mn(CO)₅Cl, CO, and CH₄, whereas the others yield the corresponding metal chlorides and ketene via β-chloride elimination. The Pt and Ir chloroacetyl complexes probably form and decompose under the reaction conditions to give the metal chloride complexes as the only isolable products.     

Thermal investigation of solid 2-methoxycinnamylidenepyruvate of some bivalent transition metal ions

Solid-state M-2-MeO-CP compounds, where M represents bivalent Mn, Fe, Co, Ni, Cu, Zn and 2-MeO-CP is 2-methoxycinnamylidenepyruvate, were synthesized for the first time. Simultaneous thermogravimetry and differential thermal analysis, differential scanning calorimetry, X-ray powder diffractometry, infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry have been used to characterize and to study the thermal behaviour of the compounds. The dehydration in all the compounds, except for iron occurs in a single step. The thermal decomposition of the anhydrous compounds occurs in two or three steps with the formation of the respective oxides, Mn₃O₄, Fe₂O₃, Co₃O₄, NiO, CuO and ZnO, as final residue. The results also provided information concerning the thermal behaviour and identification of the gaseous products evolved during the heating of these compounds.     

Thermal analysis study of some transition metal complexes by TG and DSC methods

The thermodynamic and thermal properties of [Cu(L)₂·Cl₂], [Ni(L)₂]·Cl₂, [Co(L)₂·Cl₂]; L=1,2-bis(o-aminophenoxy)ethane (BAFE), complexes have been investigated. The thermal decomposition of the complexes took place in two distinct steps in endothermic reaction up to 700°C. The activation energy E, the entropy change S ^#, enthalpy H change and Gibbs free energy change G ^# were calculated from the results of thermogravimetry analysis (TG) and heat capacity from the results of differential scanning calorimetry (DSC). It was found that the thermal stabilities and activation energies of the complexes follow the order Ni(II)>Cu(II)>Co(II) and E _Co<E _Ni<E _Cu, respectively.This revised version was published online in November 2005 with corrections to the Cover Date.     

Thermal decomposition of transition metal dithiocarbamates

Transition metal dithiocarbamate complexes, [M(S₂CN(C₂H₅)(CH₂CH₂OH)] (M=Co, Ni, Cu, Zn and Cd) have been prepared and characterized by elemental analysis and infrared spectra. Thermal decomposition of all the complexes occurs in two or three stages. The first stage in all the complexes is always fast with 65-70% mass loss. In all cases the end product is metal oxide except in the case of cobalt complex which gives Co metal as an end product. During decomposition of copper complex, first CuS is formed at ~300°C which is converted into CuSO₄ and finally CuO is formed. However, decomposition in helium atmosphere yields CuS. SEM studies of transition metal dithiocarbamates reveal needle shape crystalline phase at room temperature and formation of metal sulphide/oxide at higher temperatures. The activation energy varies in a large range of 33.8-188.3 kJ mol^-1, being minimum for the Cu complex and maximum for the Zn complex possibly due to d ¹⁰ configuration. In the case of Ni, Zn and Cd complexes the order of reaction is two suggesting bimolecular process involving intermolecular rearrangement. However, in other cases it is a unimolecular process. Large negative values of ΔS ^# for all the complexes suggest that the decomposition process involves rearrangement. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal decomposition of transition metal carboxylates

Thermal decomposition of anhydrous Cu(HCOO)₂ (1) affords H₂, CO, CO₂, H₂O, HCuOOH, CuHCOO, Cu, and the polymeric product, which contains -CH₂O,-C(O)OH-, and -RCH-0- groups. Dccomposition of1 proceeds in stages with formation of copper(I) formate as an intermediate. Possible pathways of decomposition ofI, including isomeric forms of the HCO₂ radical as intermediates, were analyzed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1406–1412, June, 1996.     

Thermal decomposition of transition metal carboxylates

Thermal solid-phase decomposition of anhydrous copper(ii) formate has been studied at 120–180 ° The rate of gas evolution during the decomposition depends on the depth of conversion and can be presented as the sum of first-order reaction rates and the rate of the autocatalytic process (a second-order reaction). The evolution of the solid phase during thermolysis has been observed by optical microscopy. The decomposition of copper formate is a complex topochemical process, a combination of homogeneous and heterogeneous transformations and dispersion of large crystals.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. l, pp. 72–76, January, 1996.     

Thermal decomposition of transition metal carboxylates

Dynamics of changes in microstresses during thermal decomposition of Cu(HCOO)₂ crystals and their effect on the thermal decomposition kinetics were studied by IR spectroscopy at 105 to 120 °C. The formation of solid intermediate HCOOCu was observed, and the dynamics of its accumulation was followed. Kinetic regularities of transformation of HCOO groups were compared with those for gas evolution.For Communication 1, see Ref. 1.Translated from Izvestiya va Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 350–354, February, 1996.     

Superconductivity of some transition metal compounds

Single crystals of niobium carbonitride were made by zone melting growth methods and single crystals of γ-NbN and δ-NbN by zone annealing crystal growth. The crystals are nonstoichiometric in contrast to the niobium carbonitride or niobium nitride prepared in reaction with nitrogen gas and niobium-niobium carbide mixtures and niobium metal, respectively. The transition temperature for superconductivity (T_c) decreases with increasing deviation from stoichiometry, and a determination of T_c is a nondestructive determination of this deviation. An instrument using the Wheatstone bridge principle is described and T_c values are listed for some nonstoichiometric single crystals of niobium carbonitride and niobium nitride.     

Mutual-diffusion of some transition metal halides

The diffusion of some zinc and cobalt salts in water have been measured using an improved version of the capillary technique. In this technique, diffusion proceeds in the absence of stirring in the bulk solution. The amount of diffusing substance which remains in the capillary is analyzed after a chosen time. Nanis' solution for three-dimensional diffusion from a capillary has been used to calculate the experimental values. The values of diffusion coefficient of zinc iodide, cobalt bromide and cobalt iodide have been obtained with a diffusion run time of four hours. A comparison has been made between the experimental and theoretical values obtained from Onsager-Fuoss theory. An attempt has also been made to explain the deviation between the experimental and theoretical values over the concentration range studied.     

Thermal and electrical studies on quinoxaline compounds of some first row transition metal ions

The chloro and bromo compounds of quinoxaline with manganese(II), cobalt(II), nickel(II) and copper(II) have been prepared in ethanolic solution. The thermal behaviour of these compounds was studied by thermogravimetry (TG) and differential thermal analysis (DTA). The thermal decomposition studies show that the compounds dichlorobis(quinoxaline) cobalt(II), dibromobis(quinoxaline) cobalt(II) and dibromobis(quinoxaline) manganese(II) form intermediate compounds before the metal halide is produced. The other compounds undergo decomposition with loss of organic ligand and the formation of the metal halide. Electrical conductivities at room temperature range from 1.4 × 10⁻⁶ Ω⁻¹ m⁻¹ for MnCl₂Q to 2.3 × 10⁻³ Ω⁻¹ m⁻¹ for both CoCl₂Q₂ and CoBr₂Q₂. There appears to be a correlation between electrical conductivity and coordination number of the metal atom. From the temperature dependence of conductivity, information has been obtained for donor or acceptor ionization energies. Decomposition temperature, as electrically determined, is in good agreement with the TG method.     

Thermal analysis of some metal alkoxides

The thermal decomposition of AI(OPrⁱ)₃, Ca(OEt)₂ and Mg(OEt)₂ has been studied using differential thermal analysis and thermogravimetric techniques. The decomposition products have been isolated and identified by gas chromatography and mass spectrometry. Probable routes for the thermal decomposition of these alkoxides have been proposed.