Thermogravimetric study of some divalent metal chelate polymers of dithiooxamide

The thermal properties of polymeric chelates of dithiooxamide with divalent copper, cobalt, zinc and nickel have been investigated. The order of thermal stability is Ni>Co～Zn>Cu, which is the same as that observed for previously studied naphthazarin and rhodizonic acid chelates. The procedural decomposition temperatures indicate that the dithiooxamide chelates, which are not aromatic, are about as stable as the aromatic naphthazarin and rhodizonic acid chelates. Several unsuccessful attempts were made to prepare beryllium and manganese (II) chelates.     

Thermal and spectral studies of some divalent metal chelates of 2,4-dinitroso-1,3-naphthalenediol

The thermal and spectral properties of the chelates of 2,4-dinitroso-1,3-naphthalenediol with copper, cobalt, nickel, and zinc have been investigated. The decreasing order of thermal stability for the metal chelates in Ni > Co ≈ Zn > Cu. With the exception of the copper chelate, which exploded, the chelates decomposed slowly. They are compared to the corresponding chelates of 2,4-dinitrosoresorcinol.     

Thermogravimetry of metal chelates of 1,1,1-trifluoropentane-2,4-dione in a flow of helium and helium containing ligand vapor

Thermogravimetry of 22 metal chelates of 1,1,1-trifluoropentane-2,4-dione, H(tfa) in a flow of helium and helium containing H(tfa) vapor is described. Samples were placed in an inserted tube in the inlet port of a gas chromatograph and heated stepwise. The presence of H(tfa) vapor in the helium flow was very effective in suppressing thermal dissociation of hydrated tfa chelates, which decomposed in a helium flow but could be completely vaporized, after dehydration, in a flow of helium containing H(tfa) vapor. The relationship between the volatility and the structure of the tfa chelates is discussed. Results obtained by the proposed method and with a conventional thermobalance are compared.     

Thermal study of Cu(II), Ni(II) and Pd(II) chelates of resacetophenoneoxime

Summary Thermal analysis of resacetophenoneoxime and its chelates of Cu(II), Ni(II) and Pd(II) is carried out. A comparison is made between the thermal stability and the solution stability of chelates and found that they oppose each other. The thermal stability for the chelates studied is PdNi>Cu and the solution stability on the other hand is Pd>Cu>Ni. The results obtained were compared with the data available in the literature for structurally similar oximes. The advantages of the reagent for gravimetric and thermogravimetric analysis of metal ions were discussed.

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Thermochemische Untersuchung der Cu(II)-, Ni(II)- und Pd(II)-Chelate von Resacetophenonoxim

Zusammenfassung Die thermische Stabilität der Chelate und ihre Stabilität in Lösung wurden verglichen und festgestellt, daß diese sich nicht entsprechen. Die erste nimmt ab in der Reihenfolge PdNi>Cu, die zweite in die Reihenfolge Pd>Cu>Ni. Die erhaltenen Ergebnisse wurden denen aus der Literatur für strukturell ähnliche Oxime gegenübergestellt. Die Vorteile des Reagenses für gravimetrische und thermogravimetrische Bestimmungen werden diskutiert.

     

Thermal and spectral properties of 2,3-, 2,4- and 3,4- dimethoxybenzoates of light lanthanides

The physico-chemical properties and thermal stability in air of light lanthanide 2,3-, 2,4- and 3,4-dimethoxybenzoates were compared and the influence of -OCH₃ substituent on their thermal stability was investigated. The complexes of these series are crystalline, hydrated or anhydrous salts with colours typical of Ln³⁺ ions. The carboxylate group is a bidentate, chelating (2,4- and 3,4-dimethoxybenzoates) or tridentate chelating and bridging ligand (2,3- dimethoxybenzoates). The thermal stability of 2,4- , 3,4- and 2,3- dimethoxybenzoates of light lanthanides was studied in the temperature range 273-1173 K. The positions of methoxy groups in benzene ring influence the thermal properties of the complexes and their decomposition mechanism. This revised version was published online in July 2006 with corrections to the Cover Date.     

Condensed heteroaromatic systems including a thiophene ring.

The thermal stabilities of 2-mercapto-3-formylbenzo[b]thiophene and its chelates with Cu(II) and Co(II), of 2-mercapto-3-iminomethylbenzo[b]thiophene and its chelates with Cu(II), Co(II), Ni(II), and Zn(II), and of N,N′-bis(2-mercaptobenzo [b]-3-thenylidene)ethylenediamine and its chelates with Cu(II), Co(II), and Ni(II) were investigated by differential-thermal and thermogravimetric analysis. The temperature of the onset of decomposition and the character of the decomposirion of the ligands and chelates were established. It was found that the investigated chelates can be arranged in the following order with respect to increasing thermal stability: Cu < Co < Zn < Ni. The most thermally stable ligand is N,N-bis (2-mercaptobenzo[b]-3-thenylidene)ethylenediamine. The effectiveness of the ligands and chelates as stabilizers for polycaproamide fibers were compared. It was found that of the investigated compounds, the copper chelates are effective stabilizers. In a study of the thermal behavior of the copper chelates in an inert gas atmosphere it was established that the character of the thermal decomposition of the most effective of them — {it(N,N′-bis)2-mercaptobenzo[b]-3-thenylidene)-ethylenediaminato} Cu(II) — is identical both in the presence of air oxygen and in a nitrogen atmosphere, i.e., the chelate does not undergo oxidation at temperatures up to 270?C.     

Bond Character of β-Diketone Metal Chelates

The vibrational spectra of molecules labeled with ²H, ¹³C, and ¹⁸O show that delocalization of double and single bonds in the six-membered ring is complete in all the metal chelates investigated of 2,4-pentanedione (acetylacetone), but not in 2,4-pentanedione itself. Mercury, on the other hand, is bonded to the central C atom of the ligands. The NMR spectra of the metal chelates of 3-mesityl-2,4-pentanedione and 3-anthryl-2,4-pentanedione show that the chelate rings have no magnetic anisotropy comparable with that of benzene. A critical appraisal is made of the questions whether it is at all justifiable to attribute any “aromatic character” to such molecules and why all comparisons with the chemical reactivity of benzene have so far led to controversial conclusions concerning the character of the bonding in the metal chelates of 2,4-pentanedione.     

Thermal behaviour of polyacrylamidoxime-copper chelates

The purpose of this work was to investigate the effect of several factors (anion type in the copper salt, pH and concentration of the salt solution) on the structure and thermo-oxidative degradation of the polyacrylamidoxime-copper chelates, by using elemental analysis, IR spectroscopy and dynamic thermogravimetry. The chelates containing copper ions as sulphate exhibit a better initial thermal stability than the polyacrylamidoxime fibre presumably due to the crosslinking generated by the intermolecular complexation of the ions; the removal of the sulphate anions takes place concomitantly with the second step of polymeric chain decomposition. The initial thermal decomposition of the chelates formed by copper ions as nitrate begins at lower temperatures as compared to the polyacrylamidoxime fibre, probably by the nitrate anion release, which partly overlaps the initial decomposition of the copper ion-crosslinked polymeric chains. Copper ions as either sulphate or nitrate catalyse the reactions involved in the main step of polyacrylamidoxime fibre decomposition; the higher the copper amount, the stronger the catalytic effect.     

希土硼氢化物的研究--Ⅴ.十二氢十二硼酸N-氧化邻二氮杂菲合希土(Ⅲ)螯合物的合成

将希土氧化物或氢氧化物同N-氧化邻二氮杂菲及十二氢十二硼酸在水—乙醇介质中反应,合成了十三个十二氢十二硼酸N-氧化邻二氮杂菲合希土螯合物。通过元素分析、红外光谱、摩尔电导率的测量。确定螯合物的化学式为[Ln(phenO)_4]_2(B_(12)H_(12))_3·nH_2O。用DTA—TG法探讨了化合物的热行为。     

The Fourier Transform Raman and infrared spectra of naphthazarin

The FT Raman spectra of the three naphthazarin polymorphs have been recorded for the first time and compared with the FTIR spectra of the polymorphs and of naphthazarin with deuterated hydroxyl groups. It is possible to distinguish between the polymorphs, to deduce that the room temperature static symmetry point group of naphthazarin is C_2v, to assign the ν(CH), σ(OH), γ(OH) vibrations and to confirm the absence of the ν(OH) mode.     

The thermal decomposition of the 5,7-dihalo-8-quinolinol rare earth metal chelates

The thermal decomposition of the 5,7-dichloro-, 5,7-dibromo- and 5,7-duodo-8-quinohnol chelates of lanthanum, cerium, praseodymium, neodymium, samarium and yttrium was investigated on the thermobalance. The chelates decomposed in the temperature range from 65 to 125°C while the oxide levels were obtained from 395 to 805°C Although the chelate thermal stability temperatures varied little with the chelating agent, the minimum oxide level temperatures were largely dependent on the halogen substitution on the 8-quinolinol molecule. Results of this study were correlated with previous studies on the rare earth metal chclatcs with 8-quinolinol and 2-methyl-8-quinolinol.     

Thermal Studies on Rare Earth Metal Ion Chelates of 8-Hydroxyquinoline, 8-Hydroxyquinaldine and Their Derivatives

The thermal behaviors of chelates of oxine, 8-hydroxyquinaldine and their derivatives (DCQ, 5, 7-dichloro-8-hydroxyquinoline; DCQ', 5, 7-dichloro-8-hydroxyquinaldine) in an air atmosphere have been studied. The order of heat stability of chelates, decreased with decreasing basicity of the ligand, i.e. oxine<DCQ<DCQ'. The presence of water or proton-containing compounds in the chelates seemed to lower heat stabilities,     

Application of the integrated ion-current technique to the study of rare-earth chelates

Several substituted acetylacetones have been prepared and reacted with holmium to give tris chelates of the form HoL₃. One of these chelates has been converted to a tetrakis chelate of the form NaHoL₄. The mass spectra of these compounds have been studied and the integrated ion currents at significant m/e values have been related to the amounts of metal chelates evaporated into the ion source of the mass spectrometer. The shape of the integrated ion-current curve is shown to give information about the nature of the evaporation process. When the β-diketone (L) is asymmetrical as in the case of 1,1,1-trifluoro-5,5-dimethylhexan-2,4-dione, the existence of geometrical isomers of the chelate, HoL₃, is reflected in the shape of the integrated ion-current curve, which shows fine structure. The results of mass spectrometric studies are compared with those of the sublimation and gas chromatographic behaviour of the metal chelates.     

Free radical crosslinking of the gas chromatographic stationary phase containing europium chelates

Summary A gas chromatographic stationary phase containing europium chelates was modified by a free radical crosslinking with 2,2-azobis(2-methylpropionitrile). The stationary phase was characterized by injections of the McReynolds series of standard solutes. A better thermal stability and an enhanced polarity was observed.Dedicated to Professor Leslie S. Ettre on the occasion of his 70th birthday.     

Structure investigation, spectral, thermal, X-ray and mass characterization of piroxicam and its metal complexes

[M(H2L)2](A)2.yH2O (where H2L: neutral piroxicam (Pir), A: Cl- in case of Ni(II) or acetate anion in case of Cu(II) and Zn(II) ions and y=0-2.5) and [M(H2L)3](A)z.yH2O (A: SO4(2-) in case of Fe(II) ion (z=1) or Cl(-) in case of Fe(III) (z=3) and Co(II) ions (z=2) and y=1-4) chelates are prepared and characterized using elemental analyses, IR, magnetic and electronic reflectance measurements, mass spectra and thermal analyses. IR spectra reveal that Pir behaves a neutral bidentate ligand coordinated to the metal ions through the pyridyl-N and carbonyl-O of the amide moiety. The reflectance and magnetic moment measurements reveal that these chelates have tetrahedral, square planar and octahedral geometrical structures. Mass spectra and thermal analyses are also used to confirm the proposed formulae and the possible fragments resulted from fragmentation of Pir and its chelates. The thermal behaviour of the chelates (TGA and DTA) are discussed in detail and the thermal stability of the anhydrous chelates follow the order Ni(II) congruent with Cu(II) Fe(II)相似文献   

Self-assembly of physically crosslinked micelles of poly(2-acrylamido-2-methyl-1-propane sulphonic acid-co-isodecyl methacrylate)-copper(II) complexes

Metal complexes were prepared by the reaction of Cu(II) chloride with sodium salt of random copolymers of 2-acrylamido-2-methylpropane sulphonic acid, AMPS, and isodecyl methacrylate, i-DMA. Composition was varied in the feed to obtain copolymers and their corresponding metal chelates with different content of i-DMA hydrophobic monomer. The copolymers and their metal chelates were characterized by Fourier transformed IR spectroscopy (FTIR) and scanning electron microscopy (SEM) as well as energy-dispersive X-ray spectroscopy (EDS). The X-ray diffraction studies revealed that the polymers and their chelates were amorphous. Also, the stabilities of the copolymers and their metal chelates were investigated using thermal methods such as TGA and DSC analysis. Lower thermal stability was found for the polymer–metal complexes compared to that of the copolymers.

Fluorescence spectroscopy was used to further confirm the copolymers and their Cu(II) metal complexes self-aggregate in water. Critical micellar concentrations become lower by metal complexation. A synergistic effect in self-assembly behaviour in water solutions of Cu(II) polycomplexes is attributed to the interplay between hydrophilic–hydrophobic interactions and electrostatic forces with Cu²⁺ ions. Physical crosslinking of polymeric micelles obtained by metal complexation led to more stable micelles. Sodium salt copolymers led to secondary aggregation while ionic crosslinking provided lonely micelles distributed through the substrate as seen by SEM. These results point to a mechanism in which cation-assisted-polymer-modified water structure plays a central role in the phase separation behaviour.     

Solid-state chelates of ethylenediamine- tetraacetate with alkali earth metals

Solid-state M-EDTA chelates, where M represents the divalent ions Mg(II), Ca(II), Sr(II) or Ba(II) and EDTA is ethylenediaminetetraacetate anion, were synthesized. Thermogravimetry, derivative thermogravimetry (TG, DTG), differential scanning calorimetry (DSC) and X-ray diffraction powder patterns have been used to characterize and to study the thermal behaviour of these chelates. The results provided information concerning the stoichiometry, crystallinity, thermal stability and thermal decomposition. This revised version was published online in August 2006 with corrections to the Cover Date.     

Thermal properties of ligands, salts and metal complexes of linear oligopyrroles

The effect of structure on the thermal properties of dipyrrolylmethanes, dipyrrolylmethenes, bis (dipyrrolylmethenes), their salts, and chelates is analyzed proceeding from the results of thermogravimetric analysis. The common tendency is a decrease in the thermal stability of compounds with a disturbed symmetry of alkyl substitution of ligands and with a higher degree of their alkylation, with the increased size of alkyl substituents, with the nitrogen atom in the five-member cycles replaced by S or O. The opposite effect occurs at the change in the mode of attaching methylene spacer in going from 2,2′- to 3,3′-bis(dipyrrolylmethenes). The effects of the themostabilization of the ligands of linear oligopyrroles in the composition of chelates and HBr salts are evaluated quantitatively.     

On the Oximine Complexes of Transition Metals: Part 110: Spectroscopic and DSC study on some [Fe(Diox·H)2L2] and [Fe(Diox)3(BOR)2] type chelates and clathrochelates

A number of 15 [Fe(Diox#x00B7;H)₂L₂] type chelates and [Fe(Diox)₃(BOR)₂] clathrochelates (Diox#x00B7;H₂ — dimethylglyoxime, glyoxime, propoxime, nyoxime, furyl-dioxime; L-pyridine, alkyl-pyridine derivatives, diethyl-phenyl-phosphine, diethyl-p-tolyl-phosphine) were obtained and characterized by means of far and middle FTIR and Mössbauer spectroscopic methods. Some structural problems were discussed on the basis of the optical data.The DSC measurements show the higher thermal stability of the clathrochelates without O—HO intramolecular hydrogen bonds (with asymmetric octahedral structure), as compared to the [Fe(Diox#x00B7;H)₂L₂] trans, symmetric chelates containing O—HO bonds. The kinetic parameters of the thermal decomposition of the complexes have been derived using the nomogram method.This revised version was published online in November 2005 with corrections to the Cover Date.     

Chemical Mechanisms of Liquid–Liquid and Solid-Phase Extraction of Metal Chelates

Conditions of the liquid–liquid and solid-phase extraction of metal chelates are compared. The analogy and differences in the behavior of chelates and the effect of stability and partition constants on the completeness of the extraction of metals are discussed.