scholarly journals Conductometric Study of Complex Formation Between Cu(II) Ion and 4-Amino-3-ethyl-1,2,4-triazol-5-thione in Binary Ethanol / Water Mixtures

2008 ◽  
Vol 5 (3) ◽  
pp. 551-556 ◽  
Author(s):  
Mohammad Hakimi ◽  
Azizollah Nezhadali ◽  
Asghar Naemi
Keyword(s):  
Dielectric Constant ◽  
Complex Formation ◽  
Stability Constant ◽  
Formation Constant ◽  
Stability Constants Of Complexes ◽  
Conductometric Study ◽  
Entropy Of Complexation ◽  
Enthalpy And Entropy ◽  
The Stability ◽  
Complexation Process

The stability constant, Kf, for the complexation of copper(II) ion with 4-amino-3-ethyl-1,2,4-triazol-5-thione (AETT ) in 0, 20, 40, 60 and 80 (v/v) % ethanol-water mixtures were determined conductometrically at different tempratures. Stability constant of resulting 1:1 complexes were being larger by increasing of temprature and ethanol percent. Stability constants of complexes vary inversly with dielectric constant of solvents. The enthalpy and entropy of complexation were determined from the temprature dependence of the formation constant. In all cases, the complexation were found to be enthalpy unstablized but entropy stablized. ࢞G0of the studied complexes were evaluated at 25°C using thermodynamic relations, the negative values of ࢞G0means that the complexation process is spantaneously.

scholarly journals The interaction of [Pd(N,N-dimethylaminopropylamine)(H2O)]2+ with dicarboxylic acids and inosine: Thermodynamic model for carboplatin drug

2012 ◽  
Vol 10 (4) ◽  
pp. 1253-1261 ◽  
Author(s):  
Mohamed Shehate ◽  
Mohamed Shoukry ◽  
Mona Ragab
Keyword(s):  
Dielectric Constant ◽  
Stability Constant ◽  
Equilibrium Constants ◽  
Chloride Ion ◽  
Dicarboxylic Acids ◽  
Ion Concentration ◽  
Antitumour Agents ◽  
Effect Of Solvent ◽  
Dna Constituents ◽  
The Stability

AbstractThe Pd(DMPA)Cl2 complex, where DMPA = N,N-dimethylaminoproylamine, was synthesized and characterized. The stoichiometry and stability constants of the complexes formed between various dicarboxylic acids and [Pd(DMPA)(H2O)2]2+ were investigated. The effect of solvent dielectric constant, chloride ion concentration of the medium and temperature on the stability constant of the cyclobutanedicaroxylic acid (CBDCA) complex was investigated. The equilibrium constants for the displacement of coordinated CBDCA by inosine, taken as an example of DNA constituents, were calculated. The results are expected to contribute to the chemistry of antitumour agents.

scholarly journals Modeling and Thermodynamic Values of Complex Equilibrium of Cobalt(II) with Diethylenetriaminepentaacetic Acid in Aqueous Solution

2021 ◽  
Author(s):  
Ghusoon Faidhi Hameed ◽  
Fawzi Yahya Waddai ◽  
Nahla Shakir Salman
Keyword(s):  
Experimental Data ◽  
Aqueous Solution ◽  
Complex Formation ◽  
Stability Constant ◽  
Wide Spectrum ◽  
Equilibrium Constants ◽  
Diethylenetriaminepentaacetic Acid ◽  
The Stability ◽  
Hoff Equation ◽  
Potentiometric Data

The paper reports the study of the complex formation of cobalt (II) with diethylenetriaminepentaacetic acid (DTPA, H5L) based on spectrophotometric (SF) and potentiometric data (pH). Complexes of different compositions were found, and equilibrium constants, as well as the stability constants of these complexes, were determined. Accumulation of complexes in proportion is calculated based on the acidity of the medium. The experimental data have been carried out by using mathematical models to assess the solution's possible existence with a wide spectrum of complex particles and to point out those which are quite sufficient to copy the experimental data. In addition, thermodynamic parameters (ΔG°, ΔH°, and ΔS°) for the studying complexes were calculated according to the values of stability constant (KST) at 25 °C obtained from the temperature dependence of stability constant by using van’t Hoff equation.

Complexation of Alkali Metal Ions by the Cryptand 4,7,13,16-Tetraoxa-1,10-diazabicyclo[8.8.5]tricosane in Several Solvents

1994 ◽  
Vol 47 (1) ◽  
pp. 123 ◽  
Author(s):  
R Dhillon ◽  
SF Lincoln
Keyword(s):  
Stability Constant ◽  
Alkali Metal ◽  
Metal Ions ◽  
Potentiometric Titration ◽  
Propylene Carbonate ◽  
Alkali Metal Ions ◽  
Factors Affecting ◽  
The Stability ◽  
Titration Study ◽  
Complexation Process

A potentiometric titration study of the complexation of metal ions (M+) by 4,7,13,16- tetraoxa-1,10-diazabicyclo[8.8.5] tricosane (C22C5) at 298.2 K and I = 0.05 (NEt4ClO4) yields log(K/dm3 mol-1) =6.07 and 5.36, 7.55 and 5.95, 6.26 and 7.56, 5.5 and 6.66, 4.57 and 5.16, and 8.14 and 14.51 when M+ = Li+, Na+, K+, Rb +, Cs+ and Ag+, respectively, where the first and second magnitudes of each pair refer to the stability constant (K) for [M(C22C5)]+ in acetonitrile and ropylene carbonate solvent, respectively. A 7Li n.m.r. tudy yields kd (298.2 K) = 428 s-1, ∆ Hd ‡ = 24.7 kJ mol-1 and ∆ Sd ‡ = -111 J K-1 mol-1 for the monomolecular decomplexation of Li+ from [Li(C22C5)]+, and kc(298.2 K) = 9.83×107 dm3 mol-1 s-1 for the complexation process in propylene carbonate. These data are compared with those for related systems and are discussed in terms of the factors affecting cryptate stability and lability.

Synthesis and Structure of a Novel Substituted Benzothiazolyl-N-phenyl-2-pyridinecarbothioamide; Kinetics of Formation and Electrochemistry of Two of its Palladium Pincer Complexes

2015 ◽  
Vol 68 (5) ◽  
pp. 731 ◽  
Author(s):  
Mark A.W. Lawrence ◽  
Yvette A. Jackson ◽  
Willem H. Mulder ◽  
Per Martin Björemark ◽  
Mikael Håkansson
Keyword(s):  
Complex Formation ◽  
Stability Constant ◽  
Palladium Complex ◽  
Coordination Complexes ◽  
Pincer Complexes ◽  
Kinetics Of Formation ◽  
Acetonitrile Solutions ◽  
The Stability ◽  
Electron Transfers ◽  
Kinetics Of

The synthesis and crystal structures of bis-N-(2,5-dimethoxyphenyl)pyridine-2,6-dicarbothioamide (dicarbothioamide I) and 6-(4,7-dimethoxy-2-benzothiazolyl)-N-(2,5-dimethoxyphenyl)-2-pyridinecarbothioamide (L1) as well as the syntheses of the palladium(ii) chloride and acetate pincer complexes are reported. The stability constant for the palladium complex formation at 25°C was found to be (2.04 ± 0.26) × 104 dm3 mol–1 and (2.30 ± 0.19) × 104 dm3 mol–1 with ΔfH = 8 ± 1 kJ mol–1, ΔfSθ = 108 ± 10 J K–1 mol–1, and ΔfH = 17 ± 4 kJ mol–1 and ΔfSθ = 140 ± 20 J K–1 mol–1 for the PdClL1 and Pd(OAc)L1, respectively. The kinetics of formation of the palladium(ii) complexes were investigated and the mechanism is proposed to be associative in nature (ΔH1‡ = 34 ± 2 kJ mol–1 and ΔS1‡ = –113 ± 8 J K–1 mol–1, and ΔH1‡ = 37 ± 3 kJ mol–1 and ΔS1‡ = –100 ± 8 J K–1 mol–1 for the PdClL1 and Pd(OAc)L1 species, respectively). The electrochemical measurements of the acetonitrile solutions revealed irreversible electron transfers consistent with the electrochemical decomposition of the ligand and its coordination complexes.

scholarly journals Stability constants of iron(II) supported and lead(II) complexes

2006 ◽  
Vol 3 (2) ◽  
pp. 336-343
Author(s):  
Baghdad Science Journal
Keyword(s):  
Complex Formation ◽  
Stability Constant ◽  
Stability Constants ◽  
Experimental Results ◽  
Enthalpy And Entropy

Overall enthalpy and entropy of complex formation were calculated from stability constant measurements at different tempreture also experimental results

scholarly journals Complex Formation Equilibria between Ag(I) and Thioureas in Propan-2-ol

2013 ◽  
Vol 2013 ◽  
pp. 1-5 ◽  
Author(s):  
Domenico De Marco
Keyword(s):  
Complex Formation ◽  
Background Electrolyte ◽  
Complex Formation Equilibria ◽  
Entropy Changes ◽  
Enthalpy And Entropy Changes ◽  
Formation Equilibria ◽  
Enthalpy And Entropy ◽  
The Stability ◽  
Tetramethyl Thiourea ◽  
Stepwise Formation

The complex formation equilibria between Ag(I) and thiourea (Tu), N methyl-Thiourea (MeTu), N,N′-dimethyl-Thiourea (Me2Tu), N,N,N′,N′ Tetramethyl-Thiourea (Me4Tu), N-ethyl-Thiourea (EtTu), N,N′ diethyl-Thiourea (Et2Tu), and N,N′-Ethylen-Thiourea (EnTu) in propan-2-ol as solvent medium have been investigated by potentiometry within the temperature range 10°C–40°C and self-determined ionic medium by (AgNO3) concentration range 6.36·10-6–3.83·10-5 m·dm−3 (no background electrolyte added). The experimental results can be interpreted with the stepwise formation of tris-coordinated complexes AgLn  (n=1–3; hereafter charge is omitted). The stability constants log βn and the standard thermodynamic changes in enthalpy (ΔHn°) and entropy (ΔSn°) for overall complex formation reactions AgI+nL=AgLn (n=1–3) have been evaluated. The reactions are exothermic in nature and entropy disfavored for all the investigated ligands. The standard enthalpy and entropy changes for the stepwise reactions AgLn-1+L=AgLn have been evaluated by difference ΔΔHn°=ΔHn°-ΔHn-1° and ΔΔSn°=ΔSn°-ΔSn-1°. The stepwise enthalpy are mutually linearly related to the corresponding entropy changes with isoequilibrium temperatures Tiso=285, 305, and 363 K for n=1, 2, or 3 respectively.

The formation of hydroxy and chloro complexes of iron(III) in chloride and perchlorate media

1969 ◽  
Vol 22 (6) ◽  
pp. 1111 ◽  
Author(s):  
AW Fordham
Keyword(s):  
Ionic Strength ◽  
Complex Formation ◽  
Stability Constant ◽  
Experimental Error ◽  
Chloride Ions ◽  
Chloro Complexes ◽  
Spectrophotometric Methods ◽  
Hydrolysis Constants ◽  
The Stability ◽  
Hydrolysis Of

The hydrolysis of iron(III) has been studied by spectrophotometric methods in KaClO4, NaCl, and CaCl2 solutions all of the same ionic strength 0.15M. The measured values of the hydrolysis constants, expressed in a form which allows for association of iron with the supporting medium, were 14.5 x 10-4 in NaClO4, 8.8 x 10-4 in NaCl, and 10.9 x 10-4 in CaCl2. In addition, the extent of complex formation between iron(III) and chloride ions has been measured in perchlorate solutions of the same ionic strength 0.15M. Assuming that only chloro complexes were formed in these systems, the stability constant of FeCl2+ formation was found to be 4.0. ��� All the results obtained were sufficiently consistent with each other, within experimental error, that the inclusion of terms to account for iron-perchlorate association was unwarranted. However, if iron-perchlorate association was assumed to exist and the results were treated accordingly, the stability constant of the associated complex was estimated to be 1.8.

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