Thermal decomposition of manganese(II)bis(oxalato)nickelate(II)tetrahydrate

Summary A mixed metal oxalate, manganese(II)bis(oxalato)nickelate(II)tetrahydrate, has been synthesized and characterized by elemental analysis, IR spectral and X-ray powder diffraction (XRD) studies. Thermal decomposition studies (TG, DTG and DTA) in air showed that the compound decomposed mainly to Mn₂O₃, MnO₂ and NiO at ca.1000°C, via. the formation of several intermediates. DSC study in nitrogen upto 500°C showed the endothermic decomposition. The tentative mechanism for the thermal decomposition in air is proposed.     

Thermal decompostion studies on nickel(II) bis(oxalato)nickelate(II) pentahydrate

The paper describes the synthesis and thermal decomposition of nickel(II)bis(oxalato)nickelate(II)pentahydrate, Ni[Ni(C₂O₄)2].5H₂O. The complex was characterized by elemental analysis, infrared, electronic, e.s.r., magnetic moment measurement and X-ray powder diffraction studies. The thermal decompostion of the complex led to NiO in air at about 338° and in nitrogen at about 720°. The activation energies (E ^*) for the dehydration and decompostion reactions in air and nitrogen were evaluated. Tentative reaction mechanisms have been suggested for the termal decompostion of the complex in air and nitrogen.

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Zusammenfassung Es wird die Synthese und thermische Zersetzung von Nickel(II) -bis(oxalato)- nickelat(II) - pentahydrat beschrieben: Ni[Ni(C₂O₄)2].5H₂O. Dieser Komplex wurde mittels Elementaranalyse, IR-Spektroskopie, ESR-Spektroskopie, der Messung des magnetischen Momentes sowie mittels Pulverdiffraktionsuntersuchungen charakterisiert. Im Ergebnis der thermischen Zersetzung entsteht NiO, in Luft bei etwa 338°, in Stickstoffatmosphäre bei ca. 720°. Die Aktivierungsenergien (E^*) der Dehydratations- und Zersetzungsreaktionen in Luft und in Stickstoff wurden ermittelt. Für die thermische Zersetzung des Komplexes in Luft bzw. in Stickstoff wurde ein Reaktionsmechanismus entwickelt.

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The authors thank the RSIC, CDRI, Lucknow for microanalysis, RSIC, NEHU, Shillong for i.r. spectra, RSIC, IIT, Madras for far i.r. spectra, RSIC, Nagpur University for thermal analysis, Dr. S. K. Datta for Forensic Science Laboratory, Guwahati, Assam for DSC and Dr. K. L. Deori of Dibrugarh University for X-ray powder diffraction photographs.     

Synthesis and thermal decomposition of cobalt(II) bis(oxalato)cobaltate(II) tetrahydrate

Cobalt(II) bis(oxalato)cobaltate(II) tetrahydrate (Co[Co(C₂O₄)] · 4H₂O) was synthesized and characterized on the basis of elemental and spectral analysis. The thermal decomposition of the complex was investigated in air and nitrogen media. In air, complete dehydration of the complex occured at 251°, followed by rapid decomposition to a mixture of CO₂O₃ and Co₃O₄ at 300°; in nitrogen, dehydration occurred at 206°, followed by decomposition to a mixture of Co and CoC₂O₄, and finally to Co + CoO, at 394° and 420°, respectively. The activation energies for the dehydration and decomposition reactions in nitrogen and air media were evaluated and a tentative reaction mechanism for the thermal decomposition of the complex was proposed.

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Zusammenfassung Das Tetrahydrat von Kobalt(H)bisoxalatokobaltat(II) wurde dargestellt und mittels Elementar- und Spektralanalyse characterisiert. Die thermische Zersetzung der Komplexe wurde sowohl in Luft- als auch in Stickstoffatmosphäre untersucht. In Luft erfolgt bei 251 °C eine vollständige Dehydratierung, gefolgt von einer schnellen Zersetzung bei 300 °C in Co₂O₃ und Co₃O₄. In Stickstoff erfolgt die Dehydratierung bei 206 °C, gefolgt von einer Zersetzung bei zunächst 394 °C in Co und CoC₂O₄, anschliessend bei 420 °C in Co und CoO. Die Aktivierungsenergien für die Dehydratierung und Zersetzung in Stickstofo- und Luftatmosphäre wurden ermittelt und für die thermische Zersetzung der Komplexe ein Reaktionsmechanismus gegeben.

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- -() ([(₂₄)₂]·4₂), - . 251 ° _{23 34} 300 °. 260 ° ₂₄, , , 394 420 °. - , .

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The authors thank the RSIC, CDRI, Lucknow for the C, H analyses and IR spectra: RSIC, IIT, Madras for the low-frequency IR spectra; RSIC, IIT, Bombay for the e.s.r. spectra; RSIC, Nagpur University for the TG and DTG measurements; and Dr. S. K. Datta of Forensic Science Laboratory, Gauhati, Assam for the DSC measurements.     

Synthesis, characterization and radiolytic properties of bis(oxalato)borate containing ionic liquids

Previously unreported bis(oxalato)borate (BOB) ionic liquids (ILs) containing imidazolium, pyridinium, and pyrrolidinium cations were prepared from the corresponding halide salts by reaction with sodium bis(oxalato)borate (NaBOB), and their properties are reported. Pulse radiolysis experiments revealed that the BOB anion scavenges solvated electrons with rate constants of 3×10⁸ M⁻¹ s⁻¹ in the ionic liquid C₄mpyrr NTf₂ and 2.8×10⁷ M⁻¹ s⁻¹ in water. This reactivity indicates that BOB ILs may be too sensitive to be used as neat solvents for nuclear separations processes in high radiation fields but may still be useful for preventing criticality while processing relatively “cold” fissile actinides.     

Thermal dehydration and decomposition of M[M(C2O4)2]·xH2O (x=3 forM=Sr(II) andx=6 forM=Hg(II))

Strontium(II) bis (oxalato) strontium(II) trihydrate, Sr[Sr(C₂O₄)₂]·3H₂O and mercury(II) bis (oxalato) mercurate(II) hexahydrate, Hg[Hg(C₂O₄)₂]·6H₂O have been synthesized and characterized by elemental analysis, reflectance and IR spectral studies. Thermal decomposition studies (TG, DTG and DTA) in air showed SrCO₃ was formed at ca. 500°C through the formation of transient intermediate of a mixture of SrCO₃ and SrC₂O₄ around 455°C. Sharp phase transition from γ-SrCO₃ to β-SrCO₃ indicated by a distinct endothermic peak at 900°C in DTA. Mercury(II) bis (oxalato) mercurate(II) hexahydrate showed an inclined slope followed by surprisingly steep slope in TG at 178°C and finally 98.66% of weight loss at 300°C. The activation energies (E ^*) of the dehydration and decomposition steps have been calculated by Freeman and Carroll and Flynn and Wall's method and compared with the values found by DSC in nitrogen. A tentative reaction mechanism for the thermal decomposition of Sr[Sr(C₂O₄)₂]·3H₂O has been proposed.     

Thermal characterization of mercury(II) bis(dialkyldithiocarbamate) complexes

Summary Solid-state M-4-MeO-Bz compounds, where M stands for bivalent Mn, Co, Ni, Cu and Zn and 4-MeO-Bz is 4-methoxybenzoate, have been synthesized. Simultaneous thermogravimetry-differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), X-ray powder diffractometry, infrared spectroscopy, elemental analysis and complexometry were used to characterize and to study the thermal behaviour of these compounds. The results led to have information about the composition, dehydration, thermal stability and thermal decomposition of the isolated compounds.     

bis(nicotinamide) and bis(N,N-diethyl nicotinamide) p-hydroxybenzoate complexes of Ni(II), Cu(II) AND Zn(II)

The mixed-ligand p-hydroxybenzoate complexes of Ni(II), Cu(II) and Zn(II) with nicotinamide and N,N-diethylnicotinamide were synthesized and characterized by elemental analysis, magnetic susceptibility measurements and mass spectrometry. The thermal behavior of the complexes was studied by simultaneous TG, DTG and DTA methods in static air atmosphere. The infrared spectral characteristics of the complexes are also discussed. The complexes contain two water molecules, two p-hydroxybenzoato (p-hba) and two nicotinamide (na) (or diethylnicotinamide (dena)) ligands per formula unit. In these complexes, all ligands are coordinated to the metal ion as monodendate ligands. In Zn(II)-na and Cu(II)-dena complexes, thep-hydroxybenzoate behaves as bidentate chelating ligand through carboxylic oxygen atoms. The decomposition pathways and the stability of the complexes are interpreted in the terms of the structural data. The final decomposition products were found to be the respective metal oxides. This revised version was published online in July 2006 with corrections to the Cover Date.     

Thermal Investigations of M[La(C2O4)3]⋅xH2O (M=Cr(III) and Co(III))

The complexes M[La(C₂O₄)₃]⋅xH₂O (x=10 for M=Cr(III) and x=7 forM=Co(III)) have been synthesized and their thermal stability was investigated. The complexes were characterized by elemental analysis, IR, reflectance and powder X-ray diffraction (XRD) studies. Thermal investigations using TG, DTG and DTA techniques in air of chromium(III)tris(oxalato)lanthanum(III)decahydrate, Cr[La(C₂O₄)₃]⋅10H₂O showed the complex decomposition pattern in air. The compound released all the ten molecules of water within ∼170°C, followed by decomposition to a mixture of oxides and carbides of chromium and lanthanum, i.e. CrO₂, Cr₂O₃, Cr₃O₄, Cr₃C₂, La₂O₃, La₂C₃, LaCO, LaCrO_x (2<x<3) and C at ∼1000°C through the intermediate formation of several compounds of chromium and lanthanum at ∼374, ∼430 and ∼550°C. Thecobalt(III)tris(oxalato)lanthanum(III)heptahydrate, Co[La(C₂O₄)₃]⋅7H₂O becomes anhydrous around 225°C, followed by decomposition to Co₃O₄, La₂(CO₃)₃ and C at ∼340°C and several other mixture species of cobalt and lanthanum at∼485°C. The end products were identified to be LaCoO₃, Co₃O₄, La₂O₃, La₂C₃, Co₃C, LaCO and C at ∼ 2>1000°C. DSC studies in nitrogen of both the compounds showed several distinct steps of decomposition along with ΔH and ΔSvalues. IR and powder XRD studies have identified some of the intermediate species. The tentative mechanisms for the decomposition in air are proposed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Mass spectrometric study of thermal stability of copper(II) bis(dipivaloylmethanate) vapour

The processes of thermal destruction of copper(II) bis(dipivaloylmethanate) (Cu(dpm)₂) in the temperature range 150°–550°C were studied by using a two-temperature variant of a double chamber Knudsen cell, with mass spectrometric recording of the gas-phase composition. The temperature range of stability of the vapour of the complex in vacuum was determined, as were those of its mixtures with oxygen in different proportions. The temperature dependence of the rate constant of the thermolysis of (Cu(dpm)₂) vapour was obtained. The thermal stability of Hdpm vapour and the influence of oxygen on the thermolysis of the ligand were studied.

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Zusammenfassung Unter Verwendung einer Zweitemperaturenvariante der Knudsenschen Doppelkammerzelle wurde mittels MS-Untersuchung der Gasphasenzusammensetzung im Temperaturbereich 150°–550°C der thermische Abbau von Kupfer(II)-bis(dipivaloylmethanat) (Cu(dpm)₂) untersucht. Es wurde der Temperaturbereich für die Stabilität der gasförmigen Komplexe in Vakuum sowie in Gemischen mit Sauerstoff in verschiedenen Verhältnissen bestimmt. Dabei wurde die Temperaturabhängigkeit der Geschwindigkeitskonstante für die Thermolyse von Cu(dpm)₂ ermittelt. Weiterhin wurde die thermische Stabilität von Hdpm-Dampf sowie der Einfluß von Sauerstoff auf die Thermolyse der Liganden bestimmt.

     

Synthesis, Characterization and Thermal Decomposition of M1[M2(C2O4)2]xH2O (x=5 for M1=Co and x=4 for M1=Cd; M2=Ni)

Cobalt bis(oxalato)nickelate pentahydrate, Co[Ni(C₂O₄)₂]5H₂O and cadmium bis(oxalato)nickelate tetrahydrate, Cd[Ni(C₂O₄)2]4H₂O have been synthesized and characterized by elemental analysis, reflectance and IR spectral studies. Thermal decomposition studies (TG, DTG and DTA ) in air showed that both the compound of cobalt and cadmium produced the oxide, MNiO_x (x=3 for M=Co; x=2 for M=Cd ) at 325 and 360°C respectively. DSC studies in nitrogen attributed only the mixture of both the metal at the end. This revised version was published online in July 2006 with corrections to the Cover Date.     

Reactions of tris(oxalato)cobaltate(III) with two-electron reductants

The tris(oxalato)cobaltate(III) complex [Co(C(2)O(4))(3)](3-), E(o)(Co)(III/II)=+0.57 V) is readily reduced by the 2e(-) reagents, Sn(II) and Ge(II), in contrast to (NH(3))(5)CoCl(2+) and (NH(3))(5)CoBr(2+), which are unreactive toward these donors. Rates for the oxalato oxidant are only 10(-3)-10(-2) as great as those for vitamin B(12a)(aquacob(III)alamin, E(o)+0.35 V at pH 1), in accord with the suggestion that reductions of corrin-bound cobalt(III) by Sn(II) and Ge(II) occur predominantly through an additional path involving Co(i). Reductions of the oxalato complex by 2e(-) donors are taken to proceed by initial formation of odd-electron intermediates (e.g., Sn(III) and Ge(III)) which react rapidly with Co(III). Such a two-step sequence is in keeping with the observed behavior of the rare reductant, Ti(II), which is found to be oxidized by [Co(C(2)O(4))(3)](3-) more slowly than (independently prepared) Ti(III) under comparable conditions.     

Kinetic Analysis of Thermogravimetric Data XXXII. DSC Study of Some [Co(Diox·H)2(amine)2]X and H[Co(Diox·H)2(N3)2] Type Complexes with Alicyclic α-dioximes

14 mixed Co(III) dioximine chelates of the types [Co(Diox·H)₂(amine)₂]X (X = Br, I, NO₃, ClO₄) and H[Co(Diox·H)₂(N₃)₂], respectively (Diox·H₂-1,2-cyclohexane dione dioxime (nyoxime), 1,2-cycloheptane dione dioxime (heptoxime) 1,2-cyclooctane dione dioxime (octoxime) were obtained and their thermal decompositions were studied in an argon atmosphere. After the dehydration of the crystallohydrates, both types of complexes exhibit 3 decomposition stages. For the [Co(Diox·H)₂(amine)₂]X type complexes (X = Br, I) the first endothermal stage is the substitution of an amine molecule for the external sphere anion and this process is followed by two exothermal decomposition stages. With H[Co(Diox·H)₂(N₃)₂] type complexes the first and third processes are relatively slow, but the second process is very fast, corresponding to a vertical portion of the TG curves. From the TG curves kinetic parameters were derived for 11 processes and the validity of a non-linear compensation law was observed. This revised version was published online in August 2006 with corrections to the Cover Date.     

三草酸合铁(Ⅲ)酸钾合成方法的改进

三草酸合铁(III)酸钾具有工业生产价值,其合成作为化学专业本科生的经典实验项目,按教材实验的效果却不尽人意。本文在严谨的化学平衡理论分析基础上,首次提出提高合成产率的关键是严格控制草酸和草酸钾的用量,改进后的合成条件为：氧化步骤H2O2的浓度为6%,水浴温度为40°C;充分氧化后,微沸2分钟;酸溶步骤中草酸稍微过量,草酸钾过量10%;结晶时做到充分冷却。经此改进,可简化操作,节约原料,实验室平均产率达87%,教学中学生实验平均产率超过70%。     

Thermal Behavior of Sr(II) and Ba(II)‐Diclofenac Complexes in Solid State: Study of the Dehydration and Thermal Decomposition

Solid state compounds of general formula Sr(Diclof)₂·5.7H₂O and Ba(Diclof)₂·4.8H₂O were obtained. Thermogravimetry (TG), differential scanning calorimetry (DSC), X‐ray diffraction powder patterns and microscopy analysis were used to characterize these compounds. Details concerning the dehydration and thermal decomposition as well as data of kinetic parameters have been described here. The kinetic behaviors of these stages were evaluated from several heating rates with samples masses of 2 and 5 mg in open crucibles under a nitrogen atmosphere. The results of the present study improve the knowledge on these compounds including their dehydration and thermal stability. The obtained data depend on the mass of the sample which results in two kinetic behavior patterns.     

Interference-free coulometric titration of water in lithium bis(oxalato)borate using Karl Fischer reagents based on N-methylformamide

A non-alcoholic coulometric reagent based on N-methylformamide (NMF) was shown to eliminate the severe interference effect caused by the alcohol component of the conventional Karl Fischer (KF) reagent on the battery electrolyte lithium bis(oxalato)borate (LiBOB). For sample amounts up to 240 μg of water, the stoichiometry of the KF reaction deviated only slightly from the ideal 1:1 ratio for the best reagent composition. Both solid and dissolved (in acetonitrile, tetrahydrofuran (THF), and ethylene carbonate/ethyl methyl carbonate) LiBOB were titrated successfully using a Metrohm 756 KF Coulometer with a diaphragm cell. The detection limit was estimated to be 0.5-1 μg of water using 100 ml of reagent in this system.     

Kinetics Analysis of the Thermal Decomposition of Poly(Butylene Adipate) Ionomers by Thermogravimetry (TG) and Derivate (DTG) Analysis

Kinetics analysis and thermal decomposition study of poly(butylene adipate) ionomers (PBAi) synthesized using the dimethyl 5‐sulfoisophthalate sodium salt (DMSI) of the diacid monomer were carried out by thermogravimetry (TG) and derivate (DTG) analysis. The decomposition kinetic parameters (activation energy, frequency factor) were calculated. The activation energy values of the PBAi‐2, PBAi‐3 and PBAi‐5 ionomers were respectively found as 164.51, 141.91 and 78.07 kJ/mol. The influence of DMSI content on the decomposition of the ionomers was investigated. The activation energy values decrease with increasing the content of DMSI. This suggests that increasing the content of DMSI makes the thermal decomposition of the ionomers easier.     

双草酸硼酸锂在锂离子电池中的应用研究进展

双草酸硼酸锂(LiBOB)是一种新型锂盐,和商业化的LiPF_66相比具有一定优势,在锂离子电池应用上受到许多学者的关注.本文介绍了LiBOB的热稳定性、分解产物无毒和保护铝箔集流体等基本性质,对LiBOB的固相和微波两种合成方法及其在不同的有机溶剂中的溶解性、电导率、高低温性能等方面进行了论述,分析了LiBOB与正极材料搭配性能和在石墨负极上的成膜性能,并对其发展方向进行了展望.