Arun K. Dey

Spectrophotometric and electrical conductance studies on chelate formation of uranyl ion with ammonium aurintricarboxylate

Abstract The formation of a coloured chelate between uranyl ion and ammonium aurintricarboxylate with λ max at 540 mμ, has been reported. The chelate has a composition of 1 : 1. The formation constant at 25°C is 5·9 ± 0·5 × 10 4 , and the free energy of formation −6·51 ± 0·05 kcal at the same temperature.

Chelate formation of ammonium aurintricarboxy-late with bivalent copper : Physico-chemical investigation of the composition, structure and stability

The formation of a coloured chelate, having λmax at 540 mμ, between cupric ions and ammonium aurintricarboxylate has been reported. It has been concluded that only one complex having metal : reagent ratio of 1:2 is formed in solution. The method adopted for investigation has been the continuous variation method, using spectrophotometric and electrical conductance measurements. It has been observed that there is an increase in acidity on mixing the reactants, which shows that hydrogen ions are liberated as a result of chelation It has been suggested that chelation occurs between the phenolic oxygen and the adjacent carboxylic oxygen. A method has been presented for the calculation of formation constant from spectrophotometric data and the value of K in the case of the chelate investigated has been calculated to be 6.45.108. The free energy of formation works out to be —14.6 kcal at 25°C.

Chromogenic reactions of titanium, zirconium and hafnium with Chrome Azurol S

Abstract The chromogenic reactions of titanium(IV), zirconium(IV) and hafnium(IV) with Chrome Azurol S have been investigated. The conditions for formation of coloured 1:1 chelates have been established and the adherence to Beers law ascertained. An interference study has been made.

A heterogeneous cobalt(II) sensitive electrode and its applications

The preparation of a heterogeneous cobalt(II) sensitive electrode, based on cation exchange resin using silicone rubber as binding material, has been described. The working pH range is 2.3 to 8.5. The selectivity coefficient for Cu(II), Ni(II), Zn(II) or Al(III) ions is found to be less than unity, and satisfactory determination of Co(II) in presence of these ions is possible. The values of stepwise stability constant of Co(II)—nitroso—R-salt complexes in solution, using the Co(II) sensitive electrode, are; log K1 6.87; and log K2 5.39 (25°; μ ≈ 0.01), which agree with literature values.

Sodium-alizarin-3-sulphonate as a colloidal electrolyte

SummaryDuring the study of the composition of metal chelates of sodium alizarin-3-sulphonate, it was realized that the colloidal nature of the reagent, especially in concentrated solutions, masks the true composition of the chelate. An investigation of the electrical conductance at various dilutions and temperatures shows that the reagent belongs to the class of colloidal electrolytes. It is recommended that for the study of the composition of chelates involving such chelating agents, extremely dilute solutions should be employed for physicochemical investigation, because under these conditions the reagent would behave as a true electrolyte.

New Octahedral Complexes of Schiff Bases Derived from 2,3-Indolinedione

Abstract Three Schiff bases derived from 2,3-indolinedione (isatin) viz. isatinsemicarbazone (iscH), isatin thiosemicarbazone (itscH) and isatin-4-phenylthiosemi-carbazone (iptscH) were prepared. All the ligands are tridentate (ONO-, ONS-donor). The metal(II) complexes formed with Co, Ni, Cu, Zn and Cd, in 1:2 stoichio-metric ratio are octahedral and do not contain water molecules. From the results of chemical analysis, magnetic susceptibility measurements employing varying currents, ir, diffuse reflectance spectral and thermal studies, the coordinating properties of the ligands and structures of the complexes have been discussed.

Stability constants of oxalate complexes of copper (II) and nickel (II) by paper electrophoresis

SummaryStability constants of copper (II) and nickel (II) oxalates have been determined by paper electrophoresis. Oxalic acid (0.005 mol dm−3) was added to the background electrolyte: 0.1 mol dm−3 HClO4. The proportions of HC2O4− and C2O42− were varied by changing the pH of the electrolyte, these anions yielding the complex ions MHC2O4+ and M(C2O4)22−, average values of the stability constants for which are 102.4 and 107.6 respectively for Cu(II), and 102.3 and 106.5 for Ni(II) (μ=0.1,30°).

Titanium(IV), zirconium(IV) and hafnium(IV) chelates of salicylaldoxime

Abstract Metal chelates of salicylaldoxime (H2BA) with titanium(IV), zirconium(IV) and hafnium(IV) have been investigated by the Bjerrum-Calvin pH-titration technique. Thermodynamic formation constants have been obtained by extrapolation of the values at various ionic concentrations. The ligand is biprotonic, the values of log K1 and log K2 (μ = 0) are 12·1 and 9·3. Titanium forms two chelates, the values of log K1 and log K2 (μ = 0) are 18·55 and 17·25 respectively. Zirconium and hafnium each form only a 1 : 1 chelate. The values of log K1 (μ = 0) are 17·9 and 16·7 respectively. The log Kμ=0 values for the ligand is 21·35 (exptl.), 21·40 (calc.) while those for the titanium, zirconium and hafnium chelates are respectively 35·60 (exptl.), 35·80 (calc.), 17·9 and 16·7 at 25°. The successive free energies (ΔF°) of the chelation reaction have also been evaluated.

Nitroso-R-salt as a reagent for the determination of palladium (II)

SummaryA procedure for the determination of palladium with nitroso-R-salt is presented. The sensitivity is 0.068 μg/cm2.ZusammenfassungEs wird ein Verfahren von zur Bestimmung Palladium mit Nitroso-R-Salz beschrieben, dessen Empfindlichkeit 0,068 μg/cm2 beträgt.

Metal chelates of rare earths: I. Composition, stability, and analytical applications of Alizarin Red S chelates of scandium and yttrium

Abstract The formation of pink colored chelates between scandium and Alizarin Red S (λ max 500 mμ) and yttrium and Alizarin Red S (λ max 510 mμ) at pH 4.0 have been reported. Absorbance measurements indicate the composition of the chelates to be 1:2 (metal:chelating agent). Adherence to Beers law is observed over a wide range of metal concentration; the color intensities are also stable within a wide range of pH. The values of log K ( K = stability constant) have been calculated by two different methods and are (1) 9.0 and 9.4 for the scandium chelate, and (2) 9.6 and 9.5 for the yttrium chelate (pH = 4.0; temperature = 25 °C). The effect of pH, temperature, time, and diverse ions on the reactions have been studied, and suggestions have been made on the possible use of Alizarin Red S in the determination of scandium and yttrium.