Synthesis and structural studies on bivalent metal complexes of benzenesulphonylhydrazine

Summary Benzenesulphonylhydrazine (HB) reacts with bivalent metal ions either in the keto-or enol forms. The complexes have been characterized by spectral (u.v., i.r., n.m.r.,), magnetic and thermal (d.t.a., d.t.g, t.g., d.s.c.) measurements. I.r. spectra suggest that HB is monodentate coordinatingvia NH or NH₂, depending on the medium of the reaction. The participation of the O=S=O group in bondingvia bridge-formation in a polymeric chain is also considered. The substitution of ethanol in the Co^II complex, [(CoB₂EtOH)_n], by H₂O, pyridine or acetonitrile was also investigated.     

Thermal decomposition of bivalent transition metal malonates in various atmospheres

The thermal decomposition of the malonates of bivalent transition metals (Mn, Fe, Co, Ni, Cu and Zn) was investigated by mainly TG-DTA, X-ray diffraction analysis and evolved gas analysis in atmospheres of N₂, CO₂ and O₂ and in the air. It was shown that CO₂ has an inhibiting effect on the decomposition whereas O₂ and air have the accelerating effects on the basis of N₂. The decomposition of the salts investigated can be classified into three groups from solid decomposition products: Mn and Zn malonates gave the metal oxides including 1–1.5 moles of elementary carbon, while Cu and Ni malonates gave the metals with 1–1.5 moles of the carbon. Fe and Co malonates in the last group gave once the metal oxides with 1-0.5 moles of the carbon and the oxides produced were subsequently reduced to the metals by the carbon. A possible reaction mechanism for the malonates was discussed and compared with those of the corresponding oxalates and succinates.     

Synthesis,characterization, electrical and biological studies on some bivalent metal complexes

Metal complexes of manganese(II), iron(II), cobalt(II), nickel(II), copper(II), zinc(II), and cadmium(II) with Schiff base derived from 2,5-dihydroxyacetophenone and s-benzyldithiocarbazate have been synthesized and characterized by elemental analysis, thermogravimetric analysis, molar conductance, molecular weight, magnetic susceptibility measurements, and electronic and infrared spectra. The molar conductivity data show them to be nonelectrolytes. The Schiff base behaves as a tridentate dibasic ONS donor towards metal ions. Thermal analyses indicate the presence of water in the complexes, making them six and four coordinates. The solid state electrical conductivity of the ligand and its complexes has been measured in the temperature range 313–414 K and the complexes are found to show semiconducting behavior. The antibacterial activities of the ligand and its complexes have also been screened against various organisms and it is observed that the coordination of metal ions has a pronounced effect on the bacterial activity of the ligand.     

Synthesis and spectroscopic studies on 3-isonicotinamidorhodanine complexes of some bivalent metal ions

Summary 3-Isonicotinamido-rhodanine (HINRd) reacts with metal ions to yield complexes of the types M(INRd)OH·nH₂O (where M=Co^II, Ni^II, Zn^II or Cd^II and n=1 or 2), Cu(HINRd)X·2H₂O (where X=Cl or Br), Pd(HINRd)Cl₂ and Cd(HINRd)X₂·H₂O (where X=Cl or Br), depending on the metal salt used and the reaction conditions. The metal complexes have been characterized by elemental analysis, molar conductivities, molecular weights, magnetic susceptibility, visible, and i.r. studies. The i.r. spectra show that HINRd binds in a bidentate or monodentate manner. The spectral and magnetic studies suggest a tetrahedral arrangement for Co^II, octahedral for Ni^II and square-planar for Pd^II. HINRd behaves as a reducing agent towards Cu^II chloride or bromide forming diamagnetic Cu^I complexes.     

Thermal,dielectric, and electrical transport properties of some bivalent metal perrhenates

Thermal, dielectric, and electron transport properties of dihydrated and anhydrous perrhenates of strontium, barium, cadmium, and lead have been investigated. The DTA of anhydrousM[ReO₄]₂ (M =Sr, Ba, Cd) compounds exhibit three reversible phase transitions with considerable thermal hysterisis for the first phase transformation. A single reversible phase transition occurs for Pb[ReO₄]₂. The parent phases of Ba[ReO₄]₂, Pb[ReO₄]₂, and Cd[ReO₄]₂ behave as semiconductors at elevated temperatures. The dielectric constants measured for Sr[ReO₄]₂ in the temperature range 30 to −160°C give a broad inflection between −40 and −70°C, which probably indicates a phase transition.     

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.     

Synthesis and spectral and antibacterial studies of bivalent transition metal ion macrocyclic complexes

A new series of the macrocyclic complexes of type [M(C₁₈H₁₆N₄O₂)X₂], where M = Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and X = Cl⁻, NO₃⁻, CH₃COO₋, has been synthesized by the condensation of succinyldihydrazide with benzil in the presence of bivalent metal ions. The complexes have been characterized with the aid of elemental analyses, conductance measurements, and electronic, NMR, and infrared spectral studies. On the basis of these studies, a six-coordinate distorted octahedral geometry in which two nitrogen and two carbonyl oxygen atoms are suitably placed for coordination toward metal ion has been proposed for all the complexes. The complexes were tested for their in vitro antibacterial activity. Some of the complexes showed remarkable antibacterial activity against some selected bacterial strains.     

Thermal degradation studies on some metal hydrazinic complexes

The paper deals with the characterization of three hydrazinic complexes with Ni, Cu and Cr respectively, by means of non-isothermal thermal methods, TG, DTG and DTA, under nitrogen atmosphere in order to investigate the structure-thermostability-thermal degradation mechanism correlation. The thermal analysis made evident the degradation mechanisms characteristic of every sample in accordance with the chemical structure. The quantitative analysis by TG-DTG afforded the estimation of the metal amount in the complex on the basis of the resulting metallic oxide nature as well as of some aspects of the thermal degradation mechanism supported by mass spectral measurements. The melting points given by DTA and confirmed by the Boetius method and the initial temperatures of thermal degradation from TG-DTG-DTA afforded to ascertain the temperature range proper for using and storing the complexes under study which show potential practical applications as drugs.     

Thermal decomposition and thermofracto-chromatographic studies of metal citrates

The thermal decomposition and kinetic parameters of thermal decomposition of Mg(II), Ca(II), Al(III), Cr(III), Fe(III), Co(II), Ni(II), Zn(II), Mn(II) and Cd(II) complex salts with citric acid were investigated on the basis of the respective thermal curves. The values of the activation energy (E _a) and reaction order (n) of the thermal decomposition were compared. Thermofractochromatograph constructed in our laboratory complies with the requirements of apparatus for separation, evolution and identification of products formed during the heating of the investigated samples in the temperature range of 293 to 600 K.

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Zusammenfassung Die thermische Zersetzung von Komplexsalzen von Mg(II), Ca(II), Al(III), Cr(III), Fe(III), Co(II), Ni(II), Zn(II), Mn(II) und Cd(II) mit CitronensÄure wurde untersucht. Die kinetischen Parameter der einzelnen Zersetzungsreaktionen wurden durch Analyse der betreffenden thermischen Kurven ermittelt und die Aktivierungsenergien (E _a) und Reaktionsordnungen (n) verglichen. Ein im Laboratorium der Autoren konstruierter Thermofractochromatograph wird den Anforderungen an eine Apparatur zur Trennung, Freisetzung und Identifizierung der beim Erhitzen der untersuchten Verbindungen im Temperaturbereich von 293–600 K gebildeten Produkte gerecht.

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The author thanks Mr. M. Bielawski for his technical assistance.     

Thermal studies on metal complexes of 5-nitroso-pyrimidine derivatives

The following cadmium(II) complexes of deprotonated 6-amino-5-nitroso-uracil (AH), deprotonated 6-amino-3-methyl-5-nitroso-uracil (BH) and neutral 6-amino-1-methyl-5--nitroso-uracil (CH) have been prepared and their thermal behaviour studied by TG and DSC techniques: CdA₂ · 3 H₂O, CdB₂ · 2 H₂O, CdB₂ and CdCl₂(CH)₂ · 2 H₂O.Dehydration processes of these complexes take place in only one step and the enthalpy values associated with them are comprised in the 42.7–80.5 kJ · mole^–1 H₂O range. The pyrolytic reactions finish in the 630–900 C temperature range, remaining as final residue in the case of CdA₂ · 3 H₂O, CdB₂ · 2 H₂O and CdB₂ complexes, cadmium oxide. The pyrolytic decomposition of CdCl₂(CH)₂ · 2 H₂O complex does not yield any residue, due to the elimination of cadmium chloride.

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Zusammenfassung Folgende Cadmium(II)-Komplexe von deprotoniertem 6-Amino-5-nitrosouracil (AH), deprotoniertem 6-Amino-3-methyl-5-nitroso-uracil (BH) und neutralem 6-Amino-1-methyl-5-nitroso-uracil (CH) wurden hergestellt: CdA₂ · 3 H₂O, CdB₂· 2 H₂O, CdB₂ und CdCl₂(CH)₂ · 2 H₂O. Das thermische Verhalten dieser Komplexe wurde mittels TG und DSC untersucht. Die Dehydratisierung der Komplexe verlÄuft in nur einem Schritt. Die Enthalpiewerte für diese Prozesse liegen im Bereich von 42.7–80.5 kJ · mol^–1 H₂O. Die pyrolytischen Reaktionen verlaufen im Temperaturbereich von 630–900C zu Ende, wobei im Falle der Komplexe CdA₂ · 3 H₂O, CdB₂ · 2 H₂O und CdB₂ Cadmiumoxid als Rückstand zurückbleibt. Die pyroytische Zersetzung von CdCl₂(CH)₂ · 2 H₂O verlÄuft wegen der Flüchtigkeit von CdCl₂ rückstandslos.

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CdA₂ · 3 H₂O, CdB₂ · 2 H₂O, CdB₂ CdCl₂(CH)₂ · 2 H₂O, A — 6--5-, B — 6--3--5- CH — 6--1--5- . . 42.7–80.5 · ^–1. 630–900, . CdCl₂(CH)₂ · 2 H₂O - , .

     

Thermal studies on metal complexes of 5-nitroso-pyrimidine derivatives

The following Zn(II) complexes of deprotonated 6-amino-5-nitrosouracil (AH), 6-amino-3-methyl-5-nitrosouracil (BH) and 6-amino-1-methyl-5-nitrosouracil (CH) have been prepared and their thermal behaviour studied by TG and DSC techniques: ZnA₂(H₂O)₂, ZnB₂ · 4 H₂O, ZnC₂ · 4 H₂O and ZnC₂(H₂O)₂ · H₂O. The values of the dehydration enthalpy of the complexes are in the 31.3–76.5 kJ mol^?1 H₂O range and, except in the first complex, the dehydration processes take place in several steps. The pyrolysis of the complexes finishes between 540 and 725° C ZnO remaining as residue.     

Thermal studies on metal complexes of 5-nitroso-pyrimidine derivatives

Four Hg(II) complexes, containing as ligands 6-amino-5-nitrosouracil (AH), 6-amino-3-methyl-5-nitrosouracil (BH) or 6-amino-1-methyl-5-nitrosouracil (CH), have been synthesized and their thermal behaviour studied by TG and DSC techniques: Hg₃Cl₆(AH)₄, HgCl₂(BH)₂· 2 H₂O, HgCl₂(BH)₂ · H₂O and HgC₂· 2 H₂O.The dehydration processes take place in only one step, with enthalpies in the range 40.2–60.0 kJ · mole^–1 H₂O.Pyrolytic processes start between 200 and 250°, in all cases the thermal stability of the corresponding pyrimidine derivative being lower than that of the free ligand. These processes finish between 600 and 750°, with no residue.

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Zusammenfassung Vier 6-Amino-5-nitrosouracil (AH), 6-Amino-3-methyl-nitrosouracil (BH) oder 6-Amino-1-methyl-5-nitrosouracil (CH) als Liganden enthaltende Hg(II)-Komplexe wurden synthetisiert: Hg₃Cl₆(AH)₄, HgCl₂(BH)₂ · 2 H₂O, HgCl₂(BH)₂ · H₂O und HgC₂ · 2 H₂O. Die Dehydratisierungsprozesse verlaufen in nur einem Schritt mit Enthalpien im Bereich von 40.2–60.0 kJ pro mol H₂O. Pyrolitische Prozesse setzen zwischen 200 und 250° ein. In allen Fällen ist die thermische Stabilität der entsprechenden Pyrimidin-Derivate geringer als die der freien Liganden. Diese Prozesse sind zwischen 600 und 750° beendet, wobei kein Rückstand zurückbleibt.

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g₃l₆()₄, gl₂( )₂ · 2 ₂O, gl₂()₂ · ₂O, g₂ · 2 ₂, — 6- -5-, — 6--3- — 6---5- . , 40.2–60.0 · ^–1 ₂. 200 250° 600–750° - . , .

     

Thermal studies on metal dithiocarbamato complexes. A review

In the present review, the work done on thermal studies of metal dithiocarbamato complexes during the period 1969–1982 are given. The thermal studies include thermogravimetry, differential thermogravimetry, differential thermal analysis, differential scanning calorimetry and mass spectrometry. Fifty-two references are included.     

Thermal studies on metal complexes of 5-nitrosopyrimidine derivatives

The following Zn(II), Cd(II), Hg(II) and Hg(I) complexes of 4-amino-1,6-dihydro-2-methylthio-5-nitroso-6-oxopyrimidine (MTH) have been prepared and their thermal behaviour studied by TG and DSC techniques: Zn(MT)₂·3H₂O, Cd(MT)·H₂O. Cd(MTH)Cl₂, Hg(MTH)Cl₂ and Hg₂(MT)(NO₃). The dehydration and dehalogenation enthalpy values were calculated.     

Thermal studies on metal complexes of 5-Nitrosopyrimidine derivatives

New 4-amino-5-nitroso-6-oxo-1,2,3,6-tetrahyaro-2-thiopyrimidine (TANH) complexes of Zn(II), Cd(II), Hg(II) and Hg(I) were prepared and their thermal behaviour was studied by TG and DSC techniques.The dehydration and deamination enthalpies of the corresponding complexes were calculated.

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Zusammenfassung Neue 4-Amino-5-nitroso-6-oxo-1,2,3,6-tetrahydro-2-thiopyrimidin-Komplexe (TANH) von Zn(II), Cd(II), Hg(II) und Hg(I) wurden dargestellt und ihr thermisches Verhalten mittels TG und DSC untersucht. Die Dehydratisierungs- und Deamminierungsenthalpien der Komplexe wurden berechnet.

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4--5--6--1,2,3,6--2- , , . .

     

Thermal studies of the reactions of vanadium(V) oxide with other transition metal oxides

Studies of the thermal behaviour of binary oxide mixtures containing vanadium(V) oxide (V₂O₅-TiO₂, V₂,O₅- MoO₃, V₂,O₅-ZrO₂ and V₂O₅-ZnO) have shown that the evolution of gaseous oxygen at fairly low temperatures is characteristic of those systems which are eflective catalysts for the oxidation of hydrocarbons. No weight changes were observed with V₂, O₅-ZnO mixtures under these conditions and, in accordance with this, zinc(II) oxide does not enhance the catalytic activity of vanadium(V) oxide. In V₂O₅-containing systems, evolution of oxygen occurs during the reduction of V₂O₅ to V₂O₄. This process is accelerated in the presence of certain metal oxides and such acceleration may be caused by structural interactions at the interface of the oxides. Among the systems studied, the formation of compounds such as Mo₆V₉O₄₀ is thought to be of little significance from the catalytic point of view.

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Zusammenfassung Die Untersuchung des thermischen Verhaltens vanadium(V)-oxid-haltiger binärer Mischungen (V₂O₅-TiO₂, V₂O₅-MoO₃, V₂O₅-ZrO₂ und V₂O₅-ZnO) ergab, daß die Entwicklung gasförmigen Sauerstoffs bei niedrigen Temperaturen für jene Systeme, welche effektive Katalysatoren der Oxidierung von Kohlenwasserstoffen sind, charakteristisch ist. Keine Gewichtsänderungen wurden bei Mischungen von V₂O₅-ZnO unter diesen Bedingungen beobachtet und dementsprechend fördert Zink(II) Oxid die katalytische Aktivität von Vanadium(V) Oxid nicht. In V₂O₅-haltigen Systemen erfolgt die Sauerstoffentwicklung während der Reduktion von V₂O₅ zu V₂O₄. Dieser Vorgang wird durch die Anwesenheit gewisser Metalloxide beschläunigt und kann durch strukturelle Wechselwirkungen an der Grenzfläche der Oxide gedeutet werden. Bei den untersuchten Systemen wird die Bildung von Verbindungen wie Mo₆V₉O₄₀ vom Gesichtspunkt der Katalyse als wenig bedeutend betrachtet.

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Résumé L'étude du comportement thermique de mélanges d'oxydes binaires contenant de l'oxyde de vanadium(V) (V₂O₅-TiO₂, V₂O₅-MoO₃, V₂O₅-ZrO₂ et V₂O₅-ZnO) a montré que le dégagement de gaz oxygène à température relativement faible est caractéristique des systèmes qui sont des catalyseurs actifs de l'oxydation des hydrocarbures. Avec les mélanges V₂,O₅-ZnO, on n'a pas observé de variations pondérales dans les mêmes conditions et, en accord avec l'observation faite, l'oxyde de zinc(II) n'augmente pas l'activité catalytique de l'oxyde de vanadium(V). Dans les systèmes contenant V₂O₅, le dégagement d'oxygène a lieu au cours de la réduction de V₂O₅ en V₂,O₄. Cette réaction est accélérée en présence de certains oxydes métalliques. Le phénomène d'accélération peut être dû à des interactions structurales à l'interface des oxydes. Dans les systèmes étudiés, la formation de composés comme Mo₆V₉O₄₀ est considérée de peu d'importance du point de vue catalytique.

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, (V₂O₅-iO₂, V₂O₅-₃, V₂O₅-ZrO₂ V₂O₅-ZnO), , , . V₂O₅-ZnO , , () . , , V₂O₅ V₂O₄. . Mo₆V₉O₄₀ , .

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The authors would like to thank Dr. D. J. Cole for carrying out the experimental work.     

Thermal studies on metal complexes of 5-nitrosopyrimidine derivatives IV

The thermal decomposition processes of the complexes of 6-amino-5-nitrosouracil with Fe(II), Co(II), Ni(II) and Cu(II) have been studied using TG and DSC techniques. Dehydration energies have been calculated from the DSC curves.     

Thermal behaviour of malonic acid,sodium malonate and its compounds with some bivalent transition metal ions

Characterization, thermal stability and thermal decomposition of transition metal malonates, MCH₂C₂O₄·nH₂O (M = Mn(II), Fe(II), Co(II), Ni(II), Cu(II), Zn(II)), as well as, the thermal behaviour of malonic acid (C₃H₄O₄) and its sodium salt (Na₂CH₂C₂O₄·H₂O) were investigated employing simultaneous thermogravimetry and differential thermal analysis (TG-DTA), differential scanning calorimetry (DSC), infrared spectroscopy, TG-FTIR system, elemental analysis and complexometry. The dehydration, as well as, the thermal decomposition of the anhydrous compounds occurs in a single step. For the sodium malonate the final residue up to 700 °C is sodium carbonate, while the transition metal malonates the final residue up to 335 °C (Mn), 400 °C (Fe), 340 °C (Co), 350 °C (Ni), 520 °C (Cu) and 450 °C (Zn) is Mn₃O₄, Fe₂O₃, Co₃O₄, NiO, CuO and ZnO, respectively. The results also provided information concerning the ligand's denticity, thermal behaviour and identification of some gaseous products evolved during the thermal decomposition of these compounds.     

Study on Semi-Glycinecresol Red complexes with bivalent metal ions

Semi-Glycinecresol Red (SGCR or H(3)SGCR) was purified by means of chromatography on cellulose and by cation-exchange. A potentiometric, spectrophotometric and ESR study on the complex formation equilibria of several bivalent metal ions with SGCR was performed. The acid-base and metal-ligand stoichiometries were determined, and the formation constants, lambda(max) and absorptivities of the visible-region absorption spectra of the corresponding proton and metal complexes were determined. The copper complexes were examined by ESR spectroscopy. Each metal ion was found to form the 1:1 and 1:2 (metal:ligand) complex species, MSGCR(-) and M(SGCR)(4-)(2), in alkaline solution. However, only Cu(II) was found to form the protonated complexes, CuHSGCR and Cu(HSGCR)(2-)(2), in weakly acidic media. SGCR is suitable as an indicator for Cu(II) in a weakly acidic solution and for Cu(II), Zn(II) and Pb(II) in alkaline solution.     

Physico-chemical studies on the chelation behaviour of acenaphthenequinone monothiosemicarbazone (AQTS) with some bivalent metal ions

Summary The stability constants of the chelates formed from acenaphthenequinone monothiosemicarbazone and magnesium(II), manganese(II), cobalt(II), nickel(II), copper(II), zinc(II) or cadmium(II) have been determined pH-metrically in 75% v/v aqueous dioxan at various ionic strengths of NaClO₄ and at different temperatures. The method of Bjerrum and Calvin^{(1, 2)} as modified by Irving and Rossotti⁽³⁾, has been used to determine the ñ and pL values. The stability constants were calculated on an IBM 360 FORTRAN-IV computer patterned after that of Sullivanet al. ⁽⁴⁾ to give _n values using a weighted least squares method. The S_min, values were also calculated. The thermodynamic stability constant has been determined by extrapolating the log K₁ vs plot at zero ionic strength. The other thermodynamic functions have been calculated from the stability constants obtained for different temperatures at constant ionic strength. The bivalent metal stability sequence of AQTS chelates is in agreement with reported metal orders for other chelating reagents. The order of free energies and enthalpies of chelate formation for AQTS are: Mn²⁺2+2+2+>Zn²⁺.