Thermal studies of some divalent metal chelates of croconic acid

The thermal properties of chelates of croconic acid and squaric acid with divalent copper, cobalt, nickel and zinc have been investigated by TG and DTA. The decreasing order of thermal stability for the decomposition of the croconate chelates was Ni > > Zn > Co=Cu and for the squarate complexes, Zn > Co=Cu > Ni. The copper croconate TG showed water loss in two distinct steps. This was rationalized on the basis of the already known Jahn-Teller effect for this molecule. The nickel squarate was thought to have a different structure than the other squarate chelates. Activation energies were calculated for the croconate chelates from their DTA curves.

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Zusammenfassung Die thermischen Eigenschaften der Chelate der Crocon- und Squarsäure mit zweiwertigem Kupfer, Cobalt, Nickel und Zink wurden durch TG und DTA untersucht. Die Abnahme der thermischen Stabilität bei der Zersetzung der Croconat-Chelate verlief von Ni>Zn>Co=Cu und der Squarat-Komplexe von Zn>Co=Cu>Ni. Die TG der Kupfercroconate wies eine Wasserabgabe in zwei deutlichen Stufen auf. Diese erklärt sich aufgrund des bereits bekannten Jahn-Teller Effekts für dieses Molekül. Für Nickelsquarat wurde eine andere Struktur angenommen als für die anderen Squaratkomplexe. Die Aktivierungsenergien für die Croconatchelate wurden aus ihren DTA-Kurven berechnet.

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Résumé Les propriétés thermiques des chélates formés par les acides croconique et squarique avec le cuivre, le cobalt, le nickel et le zinc ont été étudiées par TG et ATD. La stabilité thermique des chélates de l'acide croconique décroît dans l'ordre Ni>Zn>Co=Cu et pour l'acide squarique Zn>Co=Cu>Ni. L'étude TG du croconate de cuivre révèle une perte d'eau en deux étapes distinctes. Ceci s'explique par l'effet Jahn-Teller, déjà connu pour cette molécule. Le squarate de nickel possède sans dute une structure différente de celle des autres chélates de l'acide squarique. Les énergies d'activation des chélates de l'acide croconiqus ont été calculées à partir des courbes ATD.

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TGA DTA , , . Ni > > Zn > =u, — Zn > =Cu > Ni. TGA , . — . , , . DTA .

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Taken in part from a thesis submitted by D. A. L. to the Graduate School of the University of Notre Dame in partial fulfillment for the requirements of the Ph. D. degree.     

Thermal analysis of some metal n-benzoyl-n-phenylhydroxylamine chelates

The preparation and thermal analysis of the metal chelates of N-benzoyl-N-phenylhydroxylamine (BPHA) with Al(III), Cd(II), Co(II), Cr(III), Cu(II), Fe(III), Mn(II), Ni(II) and Zn(II) is discussed. The differential thermal analysis apparatus is described in detail. DTA and TGA curves of BPHA arid the chelates from 25 to 700° in oxygen and in nitrogen are presented.     

The thermal properties of some metal complexes of diethyldithiocarbamic acid new volatile metal chelates

The cobalt(II), nickel(II), copper(II), zinc(II), cadmium(II), silver(I) and mercury(II) complexes of diethyldithiocarbamic acid were prepared and their thermal properties determined by TG, DTA, and high temperature reflectance spectroscopy. It was found that the copper(II), nickel(II), and zinc(II) chelates were completely volatile and thus represent a new class of volatile metal chelates. Vapor pressure measurements were made on four of the metal complexes; heats of vaporization ranged from 9.3±0.2 kcal/mole for Na[Co(DDC)₃] to 24.2±0.6 kcal/mole for Zn(DDC)₂.

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Zusammenfassung Es wurden die Komplexe von Kobalt(II), Nickel(II), Kupfer(II), Zink(II), Cadmium(II), Silber(I) und Quecksilber(II) mit Diäthyldithiokarbaminsäure hergestellt und ihre thermischen Eigenschaften durch Thermogravimetrie, Differentialthermoanalyse und Hochtemperatur Reflexions Spektroskopie untersucht. Man fand, daß die Kupfer(II)-, Nickel(II)- und Zink(II)-Komplexe vollständig verflüchtigen. Sie stellen eine neue Sorte flüchtiger Metallchelate dar. Dampfdruckmessungen wurden an vier der Komplexe unternommen. Die Verdampfungswärmen liegen zwischen den Werten von 9.3±0.2 Kcal/Mol für Na[Co(DDC)₃] bis 24.2±0.6 Kcal/Mol für Zn(DDC)₂.

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Résumé On a préparé les complexes de cobalt(II), nickel(II), cuivre(II), zinc(II), cadrnium(II), argent(I) et mercure(II) avec l'acide diéthyle-dithiocarbaminique et étudié leurs propriétés thermiques par TG, ATD et spectroscopie de reflexion à haute température. On a trouvé que les complexes de cuivre(II), nickel(II) et zinc(II) volatilisent parfaitement; ils représentent une nouvelle sorte de chélates métalliques volatiles. On a fait des mesures de pression de vapeur sur quatre de ces complexes. Les valeurs des chaleurs de vaporisation s'étalent de 9.3±0.2 kcal/mole pour Na[Co(DDC)₃] jusqu'à 24.2±0.6 kcal/mole pour Zn(DDC)₂.

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[II], [II], [II], [II], [II], [I] [II] , . , [II], [II] — . ë -; 9,3±0,2 / Na[Co(DDC)₃] 24,2±0,6 / Zn[DDC]₂.

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The partial support of this work by the U. S. Air Force, Air Force Office of Scientific Research, through Grant No. AF-AFOSR 69-1620, is gratefully acknowledged. One of us (G. D'A.) wishes to thank the National Research Council of Italy, Rome, Italy, for financial support.     

Thermal decomposition of some metal chelates of substituted hydrazopyrazolones

The thermal dissociation of 1-phenyl-3-methyl-4-(X-phenylhydrazo)-5-pyrazolone metal chelates [M(XPhHyPy)](X=m-OH (I),m-OCH₃(II),m-COOH (III),p-CH₃ (IV),p-OCH₃ (V) orp-COCH₃ (VI) was studied by TG, DTG and differential thermal analysis (DTA). A rough sequence of thermal stability, obtained from the peak maximum temperatures, for the various metal chelates was Hg(II)2(II). The bonding of the ligands to metal ions was investigated by elemental analysis and infrared spectroscopy. The number and relative energies of nitrate combiantion frequencies are discussed in terms of the complexation of para-substituted hydrazopyrazolone with Th(IV) and UO₂(II) metal ions.     

Thermal studies of some divalent metal chelates of 8-mercaptoquinoline

Divalent metal chelates of 8-mercaptoquinoline (8-MQ) were prepared with copper, nickel, cobalt, zinc, lead, iron, cadmium, and mercury. The thermogravimetry and differential thermal analysis of each of the chelates were studied and a thermal stability order of Cd > Co > Ni > Zn > Pb > Hg > Fe > Cu was obtained. This order is compared with the order obtained with 8-hydroxyquinoline (8-HQ) chelates and the relative thermal stability temperatures of the chelate series are discussed in terms of ligand differences.

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Zusammenfassung Zweiartige Metallchelate von 8-Mercaptochinolinen (8-MQ) wurden mit Kupfer, Nickel, Cobalt, Zink, Blei, Eisen, Cadmium und Quecksilber hergestellt. Die einzelnen Chelate wurden durch Thermogravimetrie und Differentialthermoanalyse untersucht und eine thermische Stabilitätsreihenfolge Cd > Co > Ni > Zn > Pb > Hg > Fe > Cu wurde erhalten. Diese Reihenfolge wird mit der für 8-Hydroxychinolin-Chelate (8-HQ) erhaltenen vergleichen und die relativen Thermostabilitätstemperaturen der Chelatreihen auf Grund der Ligand-Differenzen erörtert.

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Résumé Des chélates de métaux bivalents de la mercapto-8 quinoléine (8-MQ) ont été préparés avec le cuivre, le nickel, le cobalt, le zinc, le plomb, le fer, le cadmium et le mercure. Chacun d'eux a été étudié par thermogravimétrie et par analyse thermique différentielle et l'ordre suivant de stabilité thermique a été obtenu: Cd > Co > Ni > Zn > Pb > Hg > Fe > Cu. Cet ordre de succession est comparé à celui obtenu pour les chélates de l'hydroxy-8-quinoléine (8-HQ); les stabilités thermiques des différents termes de la série des chélates étudiés sont comparées et examinées en considérant les différences de coordinants.

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8- , , , , , , . Cd>Co>Ni> >Zn>Pb>Hg>Fe>Cu. , 8- .

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P. W. B. would like to express his appreciation to the Armco Steel Corporation, the National Merit Scholarship Corporation, and the Dow Coming Corporation for their financial assistance during his career at the University of Notre Dame.     

Metal chelates of phosphonate-containing ligands-II: stability constants of some beta-styrylphosphonic acid metal chelates

The synthesis and properties of beta-styrylphosphonic acid (SPA) are reported. The values of the protonation constants of the ligand were determined potentiometrically at different ionic strengths and in the temperature range 0-65 degrees. The enthalpy and entropy of protonation have been calculated by using the van't Hoff isochore. The protonation process is endothermic and is stabilized by a relatively large positive entropy change. The stability constants of the complexes formed between SPA and the bivalent Mg, Ca, Ba, Co, Ni and Pd ions at 25 degrees and ionic strength of 0.12M KNO(3) were also determined. All measurements were carried out in 18% dimethylformamide-water mixture.     

Metal chelates of phosphonate-containing ligands-V Stability of some 1-hydroxyethane-1,1-diphosphonic acid metal chelates

A detailed study of the complexes formed between 1-hydroxyethane-1,1-diphosphonic acid and twelve metal ions, including the alkaline earth and transition non-transition metal ions, is reported. The formation constants of the protonated and unprotonated complexes are measured from potentiometric data and possible structural formulae are given. The results reveal that only mononuclear (1:1) di-, mono- and unprotonated metal chelates are formed and that the general order of stability for the unprotonated complexes is Zn > Mn > Ca > Cu > Cd > Pd > Ni > Co reverse similar Sr > Mg > Ag > Ba.     

Thermal properties of some complexes of quinolinic acid with divalent metal ions

Studies of the complexes of pyridinecarboxylic acids with divalent metal ions as a function of the position of the carboxyl groups were extended. The thermal properties of the complexes of quinoline acid (pyridine-2,3-dicarboxylic acid) with several divalent metal ions were determined by thermogravimetry (TG) and differential thermal analysis (DTA). A correlation between these compounds and others obtained by reaction between the studied metal ions with similar acids (lutidinic acid (pyridine-2,4-dicarboxylic acid) and isocinchomeronic acid (pyridine-2,5-di-carboxylic acid) is discussed in terms of the position of the carboxyl group far from the aza group. The thermal stability of the metal complexes is in the order Mn(II) > Fe(II) > Zn(II) ? Co(II) > Ni(II) > Cu(II).     

The thermal properties of some salicylaldehyde,salicylaldiimine and salicylaldehyde-ethylenediimine metal chelates

The thermal properties of Cu(II), Ni(II), Co(II), Mg and Cd salicylaldehyde ; Cu(II) and Ni(Il) salicylaldlimine; and Cu(II) and Ni(II) salicylaldehyde-ethylenediimine complexes were studied by TGA, DTA, and pyrolysis techniques using the mass spectrometer, The M(SAL)₂·2H₂O type complexes dissociate by evolution of hydrate-bound water and then total disruption of the organic ligands. Only H₂O, CO, and CO₂ were detected in. the pyrolysis gases of Cu(SAL)₂·2H₂O by the mass spectrometer.     

Photoacoustic spectra of some biological metal chelates

Photoacoustic spectra of Ni2+ in three new chelates containing azolo-2,4 pentanedione derivatives have been recorded and analysed in the visible region. The approximate symmetry of Ni2+ has been found to be octahedral. The d-d transitions in the red region show some similarity with those of nickel chloride and nickel acetate. In each case two charge-transfer bands appear in the violet region.     

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.     

The stability constants of some metal chelates of triethylenetetraminehexaacetic acid (ttha)

Stability constants for Al(III), Cd(II), Co(II), Cu(II), Fe(III), Hg(II), La(III), Nd(III), Er(III), Mg(II). Mn(II), Ni(II), Pb(II), Th(IV) and Zn(II) complexes of triethylenetetraminehexaacetic acid (TTHA) have been evaluated from data obtained by pH and pM measurements. The pM method based on measurements with the mercury electrode and the redox system Fe(III)/Fe(II) proved to be very useful when binuclear complexes are formed.     

Fractional sublimation of some metal chelates of thenoyltrifluoroacetone

Studies on the fractional sublimation of various metal β-diketone chelates have been extended to include the chelates of thenoyltrifluoroacetone (TTA). Many of the common metal chelates were found to be stable, to sublime readily, and to form well-defined zones in the vacuum fractional sublimator. Of the 17 chelates reported only those of manganese (II) and iron(II) were not volatile. The chelates of UO₂(II), Zr(IV), Pb(II), and Cr(III) partially decomposed during sublimation and their recovery was incomplete. The recovery of the sublimed chelates of Ni(II), Mg(II), Al(III), Pd(II), Co(II), Cu(II). Fe(III), Tl(III), Zn(II) and Be(II) ranged from 87 to 100%, with most recoveries being quantitative. The sublimation recrystallization zone temperatures of the various chelates are compared to those of the metal acetylacetonates and the benzoyltrifluoroacetonates; in general, the metal chelates of TTA sublime more readily than those of benzoyltrifluoroacetone but are potentially less useful for fractional sublimation separations than the corresponding metal acetylacetonates. Even so, a quantitative separation of iron(III) from Ni(II), Al(III), Mn(II), and Fe(II) is proposed that depends upon the fractional sublimation of the TTA chelates.     

The thermal dissociation of some metal cupferrate chelates

The thermal dissociation of the cupferron complexes with Cu(II), Ni, Co(II), Zn, Cd, Mn(II), Hg(II), Mg, Ca, Ba, Sr, Al, Fe(III). Ce(III), La, and Nd was studied by differential thermal analysis (DTA) and by pyrolysis into a mass spectrometer. The DTA curves consisted mainly of endothermic peaks although some contained exothermic peaks as well. The mass spectrometer showed that cupferron decomposes slightly above room temperature, giving off N₂, NO, N₂O, NH₃ and H₂O. A mechanism for the thermal dissociation of the coppcr(II) cupferrate is proposed.     

Metal chelates of phosphonate-containing ligands-I Stability of some N,N,N',N'-ethylenediaminetetra(methylenephosphonic) acid metal chelates

A potentiometric investigation of the acid dissociation constants of the octabasic ENTMP [N,N,N',N'-ethylenediaminetetra(methylenephosphonic) acid] is reported. The stability constants of protonated MH(n)L (n = 1, 2, 3 and 4) and unprotonated ML metal chelates of Mg, Ca, Ba and Cd with ENTMP have been measured. The stabilities are in the order Mg < Ca < Ba < Cd.     

The thermal properties of some metal complexes of diethyldithiocarbamic acid

The cobalt(II), cadmium(II), copper(II), mercury(II), nickel(II) and zinc(II) complexes of diethyldithiocarbamic acid were prepared and investigated by TG, DSC thin-layer chromatography and gas-liquid chromatography. Heats of fusion were determined.Permission to publish this paper has been given by the Government Chemist, Ministry of Technology.     

Extraction of chelates of some metal ions with aromatic schiff bases

Stability constants and pH₅₀ values of some Schiff bases chelates with some metal ions are reported.     

Metal chelates of phosphonate-containing ligands-IV (Stability of some 1,6-hexamethylenediamine-N,N,N',N'-tetra(methylenephosphonic) acid metal chelates)

The stability constants of the complexes formed between the anion of 1,6-hexamethylenediamine-N,N,N',N'-tetra(methylenephosphonic) acid and some transition and non-transition metal ions have been measured potentiometrically at a temperature of 25 degrees and an ionic strength of 0.1M (KNO(3)). The acid dissociation constants of the ligand and stability constants of the protonated complexes are also reported. Comparisons are made with the acid dissociation constants of the analogous compounds EDTA, ENTMP and HDTA, and possible structural formulae are given.     

Studies on nucleation from solution of some analytically important metal chelates

The combination of precipitation from homogeneous solution and Vonnegut's droplet technique is employed in the study of nucleation from solution of bis(1,2-cyclohexanedionedioxunato)Ni(II), bis(1,2-cycloheptanedionedioximato)Ni(II), bis(1,2-cyclohexanedionedioximato)Pd(II) and bis(1,2-cycloheptanedionedioximato)-Pd(II). Values of the kinetic constant, surface energy, critical radius and the number of molecules per critical nucleus are calculated and discussed in terms of the limitations of the classical theory of nucleation when applied to crystal nucleation from aqueous solutions of electrolytes.     

Thermal decomposition of some metal sulphates

The thermal decomposition temperatures of some metal sulphates (iron, copper, cobalt, nickel, zinc and lead sulphates) have been investigated by TG and DTA. The mechanism of decomposition of these sulphates is discussed, making use of additional information obtained from isothermal studies and X-ray diffraction measurements. The activation energies of these reactions were calculated and found to increase, with almost the same increments, in the order Zn<Fe<Co<Ni<Cu.