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Thermal properties of solid complexes with biologically important heterocyclic ligands

Part III. Thermal decomposition and infrared spectra of thiocyanato Mg(II) complexes with 2-hydroxypyridine, quinoline, and quinoxaline

Journal of Thermal Analysis and Calorimetry
Authors: E. Jóna, L’. Lajdová, L’. Kvasnicová, S. Lendvayová, M. Pajtášová, D. Ondrušová, P. Lizák, and S. C. Mojumdar

1. Lajdová , Ľ , Jóna , E , Šnircová , S , Miklovič , J , Segľa , P , Pajtášová , M , Ondrušová , D , Mojumdar , SC . Thermal properties of solid complexes with biologically important heterocyclic ligands

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Thermal properties of solid complexes with biologically important heterocyclic ligands

Part IV. Thermal and spectral properties of 2-chloro- and 2-bromobenzoato Cu(II) complexes with nicotinamide and different bonded water molecules

Journal of Thermal Analysis and Calorimetry
Authors: E. Jóna, L’. Lajdová, M. Loduhová, S. Lendvayová, V. Pavlík, J. Moncol’, P. Lizák, and S. C. Mojumdar

.10.003 . 6. Lajdová , Ľ , Jóna , E , Šnircová , S , Miklovič , J , Segľa , P , Pajtášová , M , Ondrušová , D , Mojumdar , SC 2009 Thermal properties of solid complexes with biologically important heterocyclic ligands

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Abstract  

A novel solid complex, formulated as Ho(PDC)3 (o-phen), has been obtained from the reaction of hydrate holmium chloride, ammonium pyrrolidinedithiocarbamate (APDC) and 1,10-phenanthroline (o-phenH2O) in absolute ethanol, which was characterized by elemental analysis, TG-DTG and IR spectrum. The enthalpy change of the reaction of complex formation from a solution of the reagents, Δr H m θ (sol), and the molar heat capacity of the complex, c m, were determined as being –19.1610.051 kJ mol–1 and 79.2641.218 J mol–1 K–1 at 298.15 K by using an RD-496 III heat conduction microcalorimeter. The enthalpy change of complex formation from the reaction of the reagents in the solid phase, Δr H m θ(s), was calculated as being (23.9810.339) kJ mol–1 on the basis of an appropriate thermochemical cycle and other auxiliary thermodynamic data. The thermodynamics of reaction of formation of the complex was investigated by the reaction in solution at the temperature range of 292.15–301.15 K. The constant-volume combustion energy of the complex, Δc U, was determined as being –16788.467.74 kJ mol–1 by an RBC-II type rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δc H m θ, and standard enthalpy of formation, Δf H m θ, were calculated to be –16803.957.74 and –1115.428.94 kJ mol–1, respectively.

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Summary A ternary solid complex Gd(Et2dtc)3(phen) has been obtained from reactions of sodium diethyldithiocarbamate (NaEt2dtc), 1,10-phenanthroline (phen) and hydrated gadolinium chloride in absolute ethanol. The title complex was described by chemical and elemental analyses, TG-DTG and IR spectrum. The enthalpy change of liquid-phase reaction of formation of the complex, Δr H Θ m(l), was determined as (-11.628±0.0204) kJ mol-1 at 298.15 K by a RD-496 III heat conduction microcalorimeter. The enthalpy change of the solid-phase reaction of formation of the complex, Δr H Θ m(s), was calculated as (145.306±0.519) kJ mol-1 on the basis of a designed thermochemical cycle. The thermodynamics of reaction of formation of the complex was investigated by changing the temperature of liquid-phase reaction. Fundamental parameters, the apparent reaction rate constant (k), the apparent activation energy (E), the pre-exponential constant (A), the reaction order (n), the activation enthalpy (Δr H Θ ), the activation entropy (Δr S Θ ), the activation free energy (Δr G Θ ) and the enthalpy (Δr H Θ ), were obtained by combination of the thermodynamic and kinetic equations for the reaction with the data of thermokinetic experiments. The constant-volume combustion energy of the complex, Δc U, was determined as (-18673.71±8.15) kJ mol-1 by a RBC-II rotating-bomb calorimeter at 298.15 K. Its standard enthalpy of combustion, Δc H Θ m, and standard enthalpy of formation, Δf H Θ m, were calculated to be (-18692.92±8.15) kJ mol-1 and (-51.28±9.17) kJ mol-1, respectively.

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Abstract  

Solid complexes of RE(NO3)3(Sm, Tb) and aspartic acid were prepared for the first time in aqueous solution. Based on chemical analysis, elemental analysis and IR spectra, the formulae of the complexes were determined as RE(NO3)3(Asp)2·2H2O (RE=Sm or Tb,Asp=Aspartic acid). Their thermal decomposition mechanism were studied from ambient temperature to 700°C using a linear heating program. The study indicates that the courses of thermal decomposition of the two complexes are very similar.

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Abstract  

Solid complexes of M(His)2Cl2 nH2O (M=Mn, Co, Ni, Cu) of MnCl26H2O, CoCl26H2O, NiCl26H2O, CuCl22H2O and L-α-histidine (His) have been prepared in 95% ethanol solution and characterized by elemental analyses, chemical analyses, IR and TG-DTG. The constant-volume combustion energies of the complexes have been determined by a rotating-bomb calorimeter. And the standard enthalpies of formation of the complexes have been calculated as well.

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Abstract  

The solid complexes of Cr(NO3)3 with L-α-amino acids (AA=Val, Leu, Thr, Arg, Phe and Try) have been prepared in 95% alcoholic, the compositions of which were identified as the general formula Cr(AA)2(NO3)32H2O by elemental and chemical analyses. The bonding characteristics of the title complexes were characterized by IR, indicating that nitrogen and oxygen atoms in the ligands coordinated to Cr3+ in a bidentate fashion. With the aid of TG-DTG and IR techniques, the complexes were subjected to thermal decomposition in an atmosphere of oxygen, presuming that the decompositions of the complexes consist of two steps and the complexes were decomposed into chromium hemitrioxide after undergoing dehydration and skeleton splitting of the complexes. The constant volume energies of combustion of the complexes were determined by a RBC-P type rotating-bomb calorimeter. According to Hess's law, the standard enthalpies of formation of the complexes were calculated as (-1831.404.40), (-2542.036.13), (-1723.813.99), (-2224.313.02), (-2911.616.53) and (-659.327.42) kJ mol-1, respectively.

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Journal of Thermal Analysis and Calorimetry
Authors: L’. Lajdová, E. Jóna, S. Šnircová, J. Miklovič, P. Segl’a, M. Pajtášová, D. Ondrušová, and S. Mojumdar

Abstract  

The stoichiometry of thermal decomposition of the complexes Ni(NCS)2(fpy)4 (I), Ni(NCS)2(bfpy)4 (II) and Ni(NCS)2(CF3Phfpy)4 (III) (where fpy=furopyridine, bfpy=benzo-[2,3]furo[3,2-c]pyridine, CF3Phfpy=2-(3-fluoromethylphenyl) furo[3,2-c]pyridine) have been investigated in nitrogen atmosphere from room temperature to 500°C by means of TG and DTG. The results revealed that release of the heterocyclic ligands occurs in two steps. IR data suggested that fpy, bfpy and CF3Phfpy ligands were coordinated to Ni(II) through the N atom of the respective heterocyclic rings and same is the case with the anionic NCS group.

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Thermal properties of solid complexes with biologically important heterocyclic ligands

Part II. Stoichiometry of thermal decomposition and infrared spectra of thiocyanatocobalt(II) complexes with furopyridine and furopyridine derivatives

Journal of Thermal Analysis and Calorimetry
Authors: L’. Lajdová, E. Jóna, J. Miklovič, P. Segl’a, L’. Kvasnicová, S. Šnircová, R. Janík, and S. Mojumdar

Abstract  

The stoichiometry of thermal decomposition of the complexes Co(NCS)2(fpy)4 (I), Co(NCS)2(Mefpy)4 (II) and Co(NCS)2(bfpy)4 (III) (where fpy = furo[3,2-c]pyridine, Mefpy = methylfuro[3,2-c]pyridine, bfpy = benzo-[2, 3]furo[3,2-c]pyridine) have been investigated in nitrogen atmosphere from room temperature (RT) to 800 °C by means of TG and DTA. The results revealed that release of heterocyclic ligands occurs in one step. Infrared data suggested that fpy, Mefpy and bfpy were coordinated to Co(II) through the nitrogen atom of the respective heterocyclic ring and anionic ligands through nitrogen atom of the NCS groups.

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