Thermodynamic stabilities. Thermodynamic parameters of some complexes of 4′-morpholinoacetophenone 4-phenyl-3-thiosemicarbazone (original) (raw)
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Thermochimica Acta, 1989
parameters AG, AH and AS and stability constants of Mg, Mn, Pb, Zn, Co and Ni complexes of o-vanillinsemicarbazone have been determined using the pH titration technique in 50% (v/v) aqueous dioxane at different ionic strengths (0.02, 0.05, 0.1 and 0.2 M NaClO,) and at different temperatures (25, 35, 40 and 45+0.1" C}. The stability constants for the complexes have been found to be entropically favoured.
Journal of Thermal Analysis and Calorimetry, 2007
The isatin-b-thiosemicarbazone (ITC) complexes of Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) were prepared and characterized by elemental analysis, as well as molar conductivity, magnetic susceptibility, FTIR, UV-Vis and 1 H NMR spectroscopic methods. The complexes were also studied for its thermal stability. They all behaviour as anhydrous complexes and its thermolysis passes through the stages of deamination (517-547 K) and complete thermal decomposition (619-735 K).
J Therm Anal Calorim, 2007
The isatin-b-thiosemicarbazone (ITC) complexes of Co(II), Ni(II), Cu(II), Zn(II), Hg(II) and Pd(II) were prepared and characterized by elemental analysis, as well as molar conductivity, magnetic susceptibility, FTIR, UV-Vis and 1 H NMR spectroscopic methods. The complexes were also studied for its thermal stability. They all behaviour as anhydrous complexes and its thermolysis passes through the stages of deamination (517-547 K) and complete thermal decomposition (619-735 K).
Transition Metal Chemistry, 1998
The proton±ligand stability constants of a-pyridoin thiosemicarbazone, a-pyridoin 2-methylthiosemicarbazone, a-pyridoin 4-methylthiosemicarbazone and apyridoin (4-phenylthiosemicarbazone) as well as the formation constants of their chelates with Cu II , Ni II , Co II , Zn II and Mn II have been determined. The Calvin± Bjerrum pH titration techniques, as modi®ed by Irving and Rossotti, were employed in aqueous media at different ionic strengths and temperatures. The stability constants of the complexes follow the order: Cu II > Ni II > Co II > Zn II >Mn II which is in accord with the Ir-ving±Williams series. The chelates derived from a-pyridoin 4-phenylthiosemicarbazone have relatively higher stability constants, which may be attributed to the presence of the benzene ring in the chain.
Journal of Thermal Analysis and Calorimetry - J THERM ANAL CALORIM, 1999
The paper describes the results of differential thermal analysis of the octahedral Fe(III) complexes of the general formula [Fe(HLn)2]Cl and Fe(HL3)L3, as well as of the corresponding ligands H2Ln (H2Ln — tridentate salicylaldehyde semi thiosemi- and S-methylisothiosemi-carabazones with n=1, 2 and 3 respectively). The decomposition of the complexes involving sulphur-containing ligands (H2L2 and H2L3) starts with sulphur elimination. In case of the complexes [Fe(HL2)]Cl and [Fe(HL3)]Cl sulphur evolves independently, whereas with Fe(HL3)L3 it is eliminated within the SCH3 group. In the former case, sulphur elimination takes place at the same temperature for both complexes. The change in the coordination mode, being a consequence of the replacement of O by S, has no essential effect on thermal stability of the coordination polyhedron. The complexes involving ONN coordination, realized with the H2L3 ligand, exhibit a comparatively highest thermal stability of the coordination polyhedron.
Journal of the Serbian Chemical Society, 2005
The stability constants of the 1:1 binary complexes of Ni(II) and Co(II) with 3-amino-1,2,4-triazole (AT), leucine (Leu) and glutamic acid (Glu), and the 1:1:1 ternary complex of them and the protonation constants of the ligands were determined potentiometrically at a constant ionic strength of I = 0.10 mol L-1 (NaClO4) in aqueous solutions at 15.0 and 25.0 ?C. The thermodynamic parameters ?Gf0, ?Hf0 and ?Sf0 are reported for the formation reactions of the complexes. The enthalpy changes of all the complexations were found to be negative but the entropy changes positive. While the driving force for the formation of the Ni(II), Co(II) ? AT complexes is the enthalpy decrease, the driving force for the ternary complexes of AT is the entropy increase.
Journal of the Serbian Chemical Society, 2007
The composition and stability of the complexes of isatin-?-thiosemicarbazone with Co(II), Ni(II), Cu(II), Zn(II), Pd(II) and Hg(II) have been investigated using spectrophotometric method at 30?C and constant ionic strength of 0.1 mol dm-3 (KNO3) in 70 % ethanol. Experimental results indicate the formation of MeL and MeL2 complexes for Ni(II) and Co(II), and MeL for Cu(II), Zn(II), Pd(II) and Hg(II) complexes, whose stability constants, ?n, have been calculated using a computerized iterative method of successive approximation.
Dyes and Pigments, 2001
The metal–ligand mole ratios and the stability constants of the Cu(II), Co(II), Ni(II) and Zn(II) complexes at 2-(5-bromo-2-pyridylazo)-5-diethylamino)phenol were determined using a spectrophotometric method at different temperatures (20, 30, 40 and 50±0.1 °C) and ionic strengths (0.05, 0.1 and 0.2) in 30% (v/v) aqueous ethanol. Plots of thermodynamic stability constants at zero ionic strength (ln K°) versus T−1 gave linear curves; the ensuing complex formation (ΔH° and ΔS°) values calculated from these plots. The changes in free energy for each metal–ligand system were evaluated.
2016
The mixed ligand complexes of the type [ML1L2]Cl2 .Where L1=Pyruvic acid thiosemicarbazone L2= Benz aldehyde semicarbazone. These complexes have been synthesized, by the reactions of metal chlorides with two different semicarbazones in 1:1:1 molar ratios. The resulting products have been characterized on the basis of elemental analysis, magnetic measurement, IR and Electronic spectra, conductivity measurement, thermal analysis, antimicrobial activities. The metal complexes show ratio 1:1:1 with metal, ligandL1 and ligand L2.The ligands are bonded through oxygen and nitrogen to metal ion. KEYWORDS-: Mixed ligand complexes, semicarbazone, thiosemicarbazone, pyruvic acid, benzaldehyde, thermal analysis, antimicrobial analysis. I.INTRODUCTION The coordination compounds have been widely used in catalysis and as potential drugs in biological fields [1,2]. Thiosemicarbazones are highly reactive compounds which form chelate complexes with metal ions. There are many complexes with Sulphur an...