Indirect polarographic determination of stability constants

Zinc, complexes of glycollic and lactic acids were studied by an indirect polarographic method using cadmium as the indicator ion. The half-wave potentials of cadmium complexes shift to more positive values in the presence of zinc. From this shift, the formation function, -n, for zinc was obtained as a function of ligand concentration and the stability constants were calculated.     

Indirect polarographic determination of stability constants

Polarograms of cadmium at different concentrations of pyridine were taken in 0·5 M potassium nitrate medium. From a plot of the half-wave potentialvs. log (Py), the co-ordination numbers of the complexes were calculated to be one and two. The indirect method was applied to the study of cobalt complexes of pyridine. From the shift in the half-wave potentials of cadmium in the presence of cobalt, a plot of\(\bar n\) vs. pA was obtained which indicated the presence of higher complexes of cobalt and pyridine. The stability constants were calculated.     

On the polarography of zinc in ethylenediamine medium

Polarography of zinc in ethylenediamine medium has been carried out. The equilibrium potentials have been determined by amalgam polarography. The standard rate constant for the electrode reaction and the stability constants of the complexes have been calculated.     

Study of indium complexes by solvent extraction and ion exchange

Complexes of indium with hydroxy carboxylic acids like glycollic, mandelic and thioglycollic acids have been investigated by the method of competitive reactions using HTTA as the auxiliary ligand. An ion exchange study has been made in some cases to confirm the results. An ion exchange study of indium fluoride complexes has also been made. The data have been analysed for the stability constants of the indium complexes.     

A polarographic study of methionine complexes of cadmium and indium

The stability constants of methionine complexes of cadmium were determined polarographically by ths method of DeFord and Hume as β₁ =6·5 × 10³, β₂ = 1·7 × 10⁶ and β₃ = 2·1 · 10⁸. The indium complexes were studied by the modified method of Momoki and Ogawa and two complexes, with β₁ = 1·7 × 10⁸ and β₂ = 8·4 × 10¹³, were identified in the concentration range studied. The haf-wave potential of uncomplexed indium ion which cannot be measured directly owing to the irreversible nature of the reduction was calculated as — 0·503 Vvs. SCE.     

A mechanism for pulsar radiation

The methods available for the determination of the stability constants of non-extractable complexes by solvent extraction are reviewed. The method proposed by Connick and McVey is valid only when no complexes of the auxiliary-ligand exist in the aqueous phase. This is applicable only at very low concentrations of the auxiliary-ligand. Hence, the stability constants calculated by this method decrease with increasing concentration and approach the theoretical values only at low concentrations of the auxiliary-ligand. It is essential, therefore, to apply the rigorous method incorporating the constants for the metal-auxiliary-ligand to calculate the stability constants which are independent of the changes in the experimental conditions. This is illustrated by few typical calculations.     

Polarography of indium in thioglycollic and ascorbic acid media

The polarographic reduction of indium in thioglycollic acid is reversible whereas in ascorbic acid it is quasireversible. The formal potentials have been determined by amalgam polarography and the stability constants calculated.     

Polarography of indium in glycollate medium

Reversible reduction of indium in glycollic acid has been followed by de polarography and the stability constants of the indium glycollate complexes calculated by the method of DeFord and Hume.     

Effect of complexing agents on the disproportionation of uranium (V)

The effect of lactate, thiocyanate, sulphate, oxalic acid and fluoride on the disproportionation of uranium (V) formed at the dropping mercury electrode has been studied. The rate constants for the disproportionation reaction are calculated and the results are discussed on the basis of the stability of the complexes.     

Investigation of the electronic absorption spectra of some pyridine derivatives iodine complexes

The electronic absorption spectra of some pyridine derivativesiodine complexes are measured and discussed. The thermodynamic constants of these complexes are calculated. It is confirmed that the stability of the complex depends on the type as well as the position of the substituent on pyridine nucleus. A linear relationship is obtained between the enthalpies — ΔH and the shift of the blue iodine band Δv of the complexes. It is also found that as the Pi electron density on the nitrogen atom increases, the stability of the complex also increases.     

Solvent extraction studies of indium-mixed chelates withβ-diketones in benzene media

Mixed chelate formation of indium with severalβ-diketones has been studied from benzene media. The extraction of indium by BFA and FFA has been carried out as a function of pH and concentration of the ligand to ascertain the nature of the complexes. The extraction of indium by a mixture ofβ-diketones,viz., BFA-BA, BFA-DBM, FFA-BA, FFA-DBM, FFA-BFA and DBM-BA has also been studied as a function of the solution parameters. The nature of the mixed complexes formed as well as their equilibrium constants, statistical and stabilisation constants have been evaluated.     

Force constants,generalised meansquare amplitudes of vibration,shrinkage constants and coriolis coupling coefficients of GeH3CCH and GeD3CCH

General Valence force constants have been evaluated for GeH₃CCH and GeD₃CCH. Generalised mean-square amplitudes of vibration have been obtained and the shrinkage constants have been calculated using the perpendicular mean-square amplitudes of vibration. Coriolis coupling constants have also been determined.     

Hydrogen bonding and solvolysis of alkyl sulphonate esters and related compounds

Hydrogen bonding between alkyl sulphonyl compounds andp-chlorophenol in carbon tetrachloride solution has been investigated by infra-red spectrometry. Analysis of the intensity of the bonded O-H stretching absorption indicates that, under the conditions employed, only 1:1 complexes are formed in significant concentration. Equilibrium constants for the complex formation have been determined at 15, 25, 35 and 45° C., and the corresponding enthalpy values derived. The strengths of the hydrogen bonds have been estimated from the positions of the bonded O-H stretching bands, and these frequencies correlate with the normal electronic effect of substitution in aryl and alkyl groups attached to the sulphonyl group. The rate of solvolysis of the methyl sulphonates in water is shown to vary inversely as the strength of the hydrogen bond formed. The possible bearing of these observations on certain aspects of the detailed mechanism of solvolysis is discussed.     

Spectrophotometric and potentiometric investigations of copper (II)-Ethanolamine complexes

Spectrophotometric and potentiometric investigations have been carried out on copper-diethanolamine system. Job plots at 900, 900 and 580 mμ have indicated the formation of CuD⁺⁺, CuD₂ ⁺⁺ and CuD₃ ⁺⁺. Then- pA curves obtained indicate the formation of CuD⁺⁺, CuD₂ ⁺⁺, CuD₃ ⁺⁺, CuDOH⁺, CuD₂OH⁺ and CuD₃OH⁺. Then- pA curves have been analyzed to obtain the stability constants of these complexes. Absorption curves of pure complexes have been computed by a graphical method. Gaussian analysis of the absorption curves of pure and hydroxy complexes show the presence of a second band, indicating that the structure is that of a distorted octahedron.     

Quadrupole interaction of Co59 in cobaltic complexes

Quadrupole coupling constants of Co⁵⁹ has been measured in several octahedral cobaltic complexes. The compounds are diamagnetic and polycrystalline in nature. The magnitudes of the coupling constants were evaluated assumingη as zero. The temperature variation of the coupling constants are correlated with the nature of Co-ligand bond and molecular motions in the solid.     

Determination of cadmium by precipitation of cadmium molybdate from homogeneous solution

A quantitative method has been developed for the determination of cadmium as cadmium molybdate by PFHS method using the technique of volatalisation of ammonia. The pH range for complete precipitation is found to be 6·0–7·6. Presence of 20–50 mmoles acetate is necessary for obtaining quantitative results. From 20–200 mg of cadmium could be conveniently determined using this method. Zinc, magnesium and nickel do not interfere. The anions such as sulphate, acetate, nitrate and chloride can be tolerated up to 50 mmoles. The precipitate has constant weight upto 750°.     

H1 and F19 nuclear magnetic resonance spectra of somep-substituted fluorobenzenes—III

The proton and fluorine nuclear magnetic resonance spectra ofp-chloro fluorobenzene andp-fluoro benzaldehyde have been studied to determine all the involved parameters. It has been found that the two meta H?H coupling constants are different inp-chloro fluorobenzene and are equal inp-fluorobenzaldehyde. C¹³?F coupling constants of fourp-substituted fluorobenzenes have also been determined.     

一类具有两个非线性控制项的系统绝对稳定的充要性条件

本文给出一类具有两个非线性控制项的系统绝对稳定的充要性判据.该判据关于未定常数均是线性的,易于检验,且有较广适用范围.     

Polarography of bismuth in malonic and chloroacetic acid media

The polarographic reduction of bismuth in the presence of malonic acid or chloroacetic acid is quasi-reversible. Bismuth forms only one complex with either chloroacetic acid or malonic acid, the complex having a co-ordination number of three. The stability constants have been calculated from the formal potentials using Lingane’s method and these values are in good agreement with those calculated from the half-wave potentials by the method suggested by Sundaresan and Sundaram.     

Thermal deflection of an elastic circular plate of variable thickness

The elastic behaviour of a solid circular plate of variable thickness under stationary temperature distribution is studied. The Young’s modulus and Poisson’s ratio are, however, supposed to be constants. Thermal deflections and moments per unit length and also the bending stresses have been determined for both clamped and simply-supported plates.