Stability Of Coordination Compounds Research Articles

Structural, photoluminescence, physical, optical limiting, and hirshfeld surface analysis of polymorphic chlorophenyl organic chalcone derivative for optoelectronic applications

The polymorphic molecule of (E)-1-(thiophen-2-yl)-3-(4-chlorophenyl) prop-2-en-1-one (2AT4C) was synthesized and grown its single crystals using slow evaporation solution growth technique. The molecular geometry and its structural deviations are studied using single crystal x-ray diffraction method. Further, for the 2AT4C molecule, the intermolecular interactions and the percentage of interactions using 2D fingerprint plots were analyzed by Hirshfeld surface analysis. The FT-IR and FT-Raman spectroscopic techniques confirm the presence of bonding, stability of coordination compounds, and material validation. The physical properties of 2AT4C crystal have been discussed using simultaneous TG/DTA/DSC thermal analysis and the vicker's microhardness test. Their physical stability in terms of melting point and vicker's hardness number was found to be 131.02 °C and Hv=21kg/mm2 respectively. PL studies project the blue light emission (378 nm) property of the grown crystal and UV-visible spectroscopic study reveals the wide optical transparency in the entire visible region with an optical band gap 3.47 eV. The third order nonlinear optical parameters such as nonlinear absorption coefficient, nonlinear refractive index, optical susceptibility, and optical limiting threshold were measured using z-scan technique under CW regime. The outstanding results of the various measures are confirms the potentiality of 2AT4C crystal for nonlinear and optoelectronic device applications.

Effect of the Composition of Mixed Aqueous Organic Solvents on the Stability of Copper(II) Complexes with Anions of Succinic and Maleic Acids

The effect aqueous ethanol solvents have on the stability of coordination compounds between Cu(II) ions and anions of succinic (Y2–) and maleic (L2–) acids is studied via UV–Vis spectrophotometry. Logarithms of stability constants for succinate and maleate complexes are compared to ones obtained via potentiometric titration. Quantum chemistry calculations are performed for the structures of maleic and succinic acids and complexes of them with Cu(II) ions to explain the difference between the stabilities of succinate and maleate complexes.

Stability of coordination compounds of Ni2+ and Co2+ ions with succinic acid anion in water–ethanol solvents

Stability constants of the coordination compounds of nickel(II) and cobalt(II) ions with succinic acid anion in water–ethanol solvents are determined via potentiometric titration at ionic strength of 0.1 and at T = 298.15 K. It is found that logβ values of monoligand complexes of these ions and succinic acid anions rise along with the content of ethanol in solution (XEtOH = 0–0.7 mole fractions). Based on an analysis of the thermodynamic characteristics of the solvation of the reagents involved in complex formation, it is found that the increased stability of succinate complexes of nickel(II) and cobalt(II) ions in water–ethanol solvents is mainly determined by the weakening of the solvation of succinic acid anion (Y2−).

Composition and stability of complexes of maleic and succinic acids with Cu2+ ions in water-ethanol solutions at 298 K

The composition and stability of coordination compounds of the anions of maleic (H2L) and succinic (H2Y) acids with copper(II) ions in water-ethanol solutions is studied by means of potentiometric titration at a sodium perchlorate ionic strength of 0.1 and a temperature of 298.15 K. The composition of the water-ethanol solvent was varied from 0 to 0.7 molar parts of ethanol for maleic acid and from 0 to 0.4 molar parts for succinic acid. The stability of monoligand complexes of copper ions with the anions of maleic and succinic acids grows with increase of ethanol concentration from 3.86 to 6.62 for logβCuL and from 2.98 to 6.01 for logβCuY. It is shown that a monotonic rise in stability upon an increase in the content of ethanol in solution is observed, while the values of logβCuL change more sharply. The succinic acid anion forms a stronger complex with copper ions than maleic acid anions do at an ethanol content of 0.4 molar parts. The possibility of the formation of a protonated CuHY+ particle is established.

Stability of coordination compounds of Co2+ and Ni2+ ions with maleic acid anion in aqueous isopropanol solutions

Composition and stability of coordination compounds of nickel(II) and cobalt(II) ions with maleic acid anion in aqueous isopropanol solutions (H2O-IPA) of composition χIPA = 0–0.5 mole fraction was studied by potentiometric titration at ionic strength of 0.1 maintained with sodium perchlorate at 298.15 K. Monoligand complexes of Ni2+ and Co2+ ions with maleic acid anion become stronger when isopropanol content rises. In the solvent of the studied composition, Co2+ ions form less stable complexes than Ni2+ ions that corresponds to the Irving-Williams series established for aqueous solutions. Variations in complex stability are more expressed at small IPA content and differ within experimental error at χIPA = 0.5 mole fraction. Obtained results were compared with literature data for akin compounds.

Variation of thermodynamic parameters of crown ether-metal complex formation and reactant solvation in binary nonaqueous solvent mixtures

General trends in the variation of thermodynamic parameters of complex formation of crown ethers with d-metal ions in binary nonaqueous solvent mixtures were determined. An equation was proposed for predicting variation of the stability of coordination compounds upon replacement of one nonaqueous solvent by another on the basis of the change in the Gibbs energy of solvation of the central ion. Calculation of the Gibbs energies for the formation of the [Ag18C6]+ ion in acetonitrile and a number of nonaqueous solvents confirmed the predictive ability of the proposed equation.

The influence of medium on the stability of coordination compounds 4. The system In(tiron)−-NaC1O4-C2H5OHH2O

The stability constants of complex anion In(tiron)− in mixed solvents of ethanol-water with weight percentages of ethanol being 0,5,15,25,35 and 50 have been measured spectrophotometrically at 293 K, using NaClO4 as supporting electrolyte with ionic strength ranging from 0.1 to 3.3mol·dm−3. The thermodynamic stability constants of In(tiron)− in various mixed solvents have been obtained by a polynomial approximation equation based on Pitzer's theory. As a comparison, the traditional Debye-Huckel equation has also been used to treat the same data. The results show that this polynomial approximate method is obviously superior to the old one. It was discovered that there is a linear relation between the thermodynamic stability constants of In (tiron)− and the mole fraction of organic component in mixed solvents or the reciprocal of dielectric constants of mixed solvents. The medium effect and the standard free energy of transfer, ΔG°tr, for the coordination reaction: In3+ + tiron4- = In(tiron)− have also been discussed.

The Correlation Between Transition Metal NMR Chemical Shifts and the Stability of Coordination Compounds

Linear correlations of transition metal NMR chemical shifts with the logarithm of overall stability constants for six different series of complexes of Co(III), Rh(III), Rh(I) and Pt(II) have been found. Each case is presented and discussed. The relation is interpreted with a simplified version of Ramsey's equation for the chemical shift. A derivation of a relation of the type delta = m - k logK using ligand field theory is proposed.

Thermoanalytical approach to the study of the kinetic and thermodynamic stability of coordination compounds and clathrates

The possibilities of the modern thermoanalytical methods for the study of the kinetic lability and thermodynamic stability of coordination compounds and inclusion compounds are discussed. The nonisothermal kinetics allowed to obtain the kinetic stability series of compounds (iso-entropy, iso-enthalpy and with iso-kinetic temperature), these series are considered from the point of view of the ligands substitution mechanism. The quasi-equilibrium thermogravimetry was used for the forming of thermodynamic stability series and for the search of the iso-equilibrium temperature.

The influence of medium on stability of coordination compounds: I. The system Cu(SCN)+-NaNO3-C2H5OH-H2O

The stability constants of Cu(SCN)+ in the titled system have been determined by spectro-photometric measurements at 25°C for 0, 5, 10, 15, 20 and 25 wt% of ethyl alcohol in mixed solvents. The total ionic strength of the solution are 0.2-2.0 mol·dm−3 and pH 1.5-1.6. On basis of Pitzer's theory, a method of determining thermodynamic stability constants of coordination compounds in mixed solvents by curve fitting technique have been proposed. The stability constants of Cu(SCN)+ in mixed solvents have been correlated with composition and dielectric constant of the solvent mixture.

On the thermal stability of some coordination compounds generating mixed oxides with perovskitic structure II

Abstract Following our research concerning the thermal stability of coordination compounds generating mixed oxides [1], this paper deals with the non-isothermal kinetics of solid-state decompositions of some mononuclear coordination compounds (MCC) of La and Co, and a polynuclear coordination compound (PCC) of the pair La-Co with salicylic acid. The paper is part of a research series looking to obtain some mixed oxides with general formula ABO 3 , specific to perovskitic structure, where A is a rare earth ion, and B is a transition metal ion, by thermal decomposition of some polynuclear coordination compounds. The importance of mixed oxides of La with perovskitic structure [2–4] is due to their catalytic properties for oxidation-reduction reactions [5], dehydrogenation [6] and depollution processes, which are similar to those exhibited by platinum catalysts.

A comparative study of the thermal stability of coordination compounds by thermoanalytical methods

The informative capacity of thermal analysis in the evaluation of the thermal stability of coordination compounds involving the evolution of volatile ligands is discussed. The temperature of decomposition under quasi-equilibrium conditions (Q-derivatograph, quasi-isobaric, quasi-isothermal operation) is suitable for characterizing the thermodynamic stability of compounds. The initial temperature of decomposition at linear heating indicates the reaching of a defined value of the rate constant (depending on the sensitivity of the sensing device of the instrument and on experimental conditions). The temperature sequence of increasing thermal stability may not coincide with the sequence of increasing activation energy values, since in the majority of cases it demands on the value of activation enthropy.

Periodic law of D. I. Mendeleev and the stability of co-ordination compounds

Periodic law of D. I. Mendeleev and the stability of co-ordination compounds

Stability of co‐ordination compounds

Stability of co‐ordination compounds