Study of iron(II) complexes with halides and thiocyanate in acetonitrile

1970 ◽  
Vol 48 (9) ◽  
pp. 1414-1419 ◽  
Author(s):  
Byron Kratochvil ◽  
Robert Long
Keyword(s):  
Formation Constants ◽  
Ratio Method ◽  
Mole Ratio Method ◽  
Stepwise Formation

In acetonitrile, iron(II) forms stable 1:1 complexes with chloride, bromide, and iodide and both 1:1 and 1:2 complexes with thiocyanate. Stepwise formation constants for the complexes were determined spectrophotometrically by a mole-ratio method. The log K values are: FeCl+, 5.8; FeBr+, 5.5; FeI+,4.3; Fe(SCN)+, 5.5; and Fe(SCN)2, 3.7.

Raman Spectral Studies of Cadmium–Nitrite Interactions in Aqueous Solutions and Crystals

1975 ◽  
Vol 53 (10) ◽  
pp. 1414-1423 ◽  
Author(s):  
Donald E. Irish ◽  
Roderick V. Thorpe
Keyword(s):  
Aqueous Solutions ◽  
High Frequency ◽  
Deformation Mode ◽  
Formation Constants ◽  
Ratio Method ◽  
Spectral Studies ◽  
Nitrite Concentration ◽  
Nitrite Ion ◽  
Mole Ratio Method ◽  
Raman Spectral

Raman spectra of aqueous solutions containing Cd2+ and NO2− clearly reveal the presence of solvated nitrite ion and of complexes. A band at 861 cm−1 is characteristic of the latter. The free nitrite concentration was measured from the intensity of the 817 cm−1 line and the average ligand number was evaluated for solutions with composition prescribed by the mole-ratio method. Four cumulative formation constants were deduced: β1 = 61.6; β2 = 993; β3 = 2390; β4 = 1899. Evidence that nitrite chelates Cd2+ through the two oxygen atoms is presented. The diagnostic spectral evidence consists of a high intensity, high frequency deformation mode and low intensity N—O stretching Raman bands with frequencies almost identical to those of the solvated nitrite ion. Data are also presented for solid Cd(NO2)2 and Kx−2Cd(NO2)x(x = 3,4,5).

Magnetophoretic mole-ratio method in solvent extraction systems

2020 ◽  
Vol 1111 ◽  
pp. 60-66
Author(s):  
Hitoshi Watarai ◽  
Mariko Kurahashi
Keyword(s):  
Solvent Extraction ◽  
Ratio Method ◽  
Mole Ratio Method

Stabilities of Vanadyl Complexes with Methionine, Phenylalanine, and Threonine

1974 ◽  
Vol 29 (7-8) ◽  
pp. 336-338
Author(s):  
B.S. Sekhon ◽  
S.L. Chopra
Keyword(s):  
Free Energy ◽  
Ionic Strength ◽  
Stability Constants ◽  
Thermodynamic Stability ◽  
Chloride Solution ◽  
Formation Constants ◽  
Potassium Chloride Solution ◽  
Vanadyl Complexes ◽  
Overall Stability ◽  
Stepwise Formation

Abstract Stepwise formation constants corresponding to 1:1 vanadyl complexes with methionine, phenylalanine and threonine have been determined at 25 °C, and at various ionic concentrations, viz. 0.01, 0.1 and 0.3 ᴍ , maintained by the addition of potassium chloride solution. Thermodynamic stability constants have been obtained by extrapolation of log K values to zero ionic strength. Logarithms of the overall stability constants (log K (u = 0)) are 7.72 for methionine, 7.70 for phenyl­alanine and 7.44 for threonine complexes. The corresponding free energy changes (⊿G0) are - 10.53, - 10.51, - 10.15 kcal-mol-1 respectively.

scholarly journals Determination of Stability Constants and Thermodynamic parameters of Cefotaxime –Fe(III) Complex at Different Temperatures

2020 ◽  
Vol 45 (4) ◽  
Author(s):  
O. V. Ikpeazu ◽  
I. E. Otuokere ◽  
K. K. Igwe
Keyword(s):  
Stability Constants ◽  
Chelating Agent ◽  
Continuous Variation ◽  
Molar Ratio ◽  
Variation Method ◽  
Ratio Method ◽  
Lactam Antibiotic ◽  
Different Temperatures ◽  
Mole Ratio Method ◽  
Continuous Variation Method

Cefotaxime, a β-lactam antibiotic, has a structure which enables it to act as a chelating agent. The formation of Fe(III) complex with cefotaxime has been studied colorimetrically at an absorption maximum of 480 nm at different temperatures. The data showed that Fe(III) and cefotaxime combine in the molar ratio of 1:1  at pH 7.4 with ionic strength maintained using 0.1M KNO3. The stability constants of the complex were calculated to be 1.56 - 1.90 x 104 by continuous variation method and 1.34 - 1.71 x 104 by mole ratio method at 25 and 40 oC respectively. ∆HƟ values for the complex were calculated to be -1.02 x 104 and -1.05 x 104 J by continuous variation method and mole ratio method respectively. ∆GƟ of the complex were calculated to be -2.44 – (-2.51) x 104 J by continuous variation method and -2.41- (- 2.48)  x 104 J by mole ratio method at 25 and 40 oC.  ∆SƟ of the complex were calculated to be 2.44 - 2.51 x 104 J/K by continuous variation method and -2.41 -2.48) x 104 J/K by mole ratio method at 25 and 40 oC respectively. Cefotaxime is a good chelating agent and can be an efficient antidote in the therapy of copper overload or poisoning.  

Die Isopolymolybdationen in wäßrigen Medien im Bereich Z ≦ 1,14 / Concerning Isopolymolybdate Ions in Aqueous Media in the Range Z ≦ 1.14

1980 ◽  
Vol 35 (1) ◽  
pp. 45-56 ◽  
Author(s):  
Karl-Heinz Tytko ◽  
Georgios Petridis ◽  
Bernd Schönfeld
Keyword(s):  
Main Product ◽  
Structural Parameters ◽  
Aqueous Media ◽  
Ratio Method ◽  
Intensity Difference ◽  
Ionic Medium ◽  
Theoretical Investigations ◽  
Detailed Evaluation ◽  
Mole Ratio Method ◽  
Statistical Certainty

The system H+/MoO42- was investigated by Raman spectroscopy in the range Z = 0 to 1.14 at initial concentrations CMoO₄ 2- = 0.02 to 2M and concentrations of the ionic medium CMe+ = 2CMoO₄ 2- to 3M Me(Cl,NO3) (Me=Li, Na, K,NH4 , Mg/2). The mole-ratio method and intensity difference diagrams do not indicate any species between MoO42- and Mo7O246- contrary to propositions in recent papers. A detailed evaluation of the extensive data shows the possible portion of such species to be < 3 % , this value having a statistical certainty of 95%. Comparing the solutions having Z = 1.1 by fingerprint procedures, in all cases Mo7O246- is the first main product (detectable by static methods) irrespective of the nature and concentration of the ionic medium. Thus, Mg2+ ions do not influence the course of aggregation of molybdate ions as has been proposed in the literature. This is in accordance with theoretical investigations since the Mo7O246- ion has the distinction of a number of favourable structural parameters in the system that become operative in case of scarcity of H+ ions.

Thermodynamic Study of Ce4+ /Ce3+ Redox Reaction in Aqueous Solutions at Elevated Temperatures: 1. Reduction Potential and Hydrolysis Equilibria of Ce4+ in HCIO4 Solutions

1992 ◽  
Vol 47 (9) ◽  
pp. 974-984 ◽  
Author(s):  
B. A. Bilal ◽  
E. Müller
Keyword(s):  
Redox Reaction ◽  
Elevated Temperatures ◽  
Formation Constants ◽  
Cyclic Voltammetric ◽  
Voltammetric Measurement ◽  
Constant Potential ◽  
Increasing Temperature ◽  
Aqueous Hclo ◽  
Stepwise Formation ◽  
Cyclic Voltammetric Measurement

AbstractThe redox potential (E) of the couple Ce4+/Ce3+ has been determined up to 368 K by means of cyclic voltammetric measurement in aqueous HClO4 solutions with cHClO4 decreasing from 7.45 to 0.023 mol kg-1 . A constant potential of (1.741 V)298 K, resp. (1.836 V)368K, indicating the existence of pure unhydrolysed Ce4+ was obtained at cHClO4 ≥ 6.05 m. At lower HClO4 concentration, the potential as a function of the HClO4 molality, as well as of the pH shows 4 further distinct steps. At 298 K, for instance, the potential became nearly constant at pH values of 0.103, 0.735,1.115, after which it drastically decreased, respectively at 1.679, just before the precipitation of Ce(OH)4 occurred. The curves indicate obviously the stepwise formation of the Ce(IV) mono-, di-, tri- and tetrahydroxo complexes. The slope of the curves E vs. pH increased gradually with increasing temperature. ΔS and ΔH of the redox reaction were determined as functions of T at the different HClO4 concentrations. ΔSis positive at cHClO4 > 1.85 m and turns to be negative at lower concentrations. ΔHis negative at all HClO4 concentrations studied. The cumulative formation constants ßi, of the Ce(IV) hydroxo complexes and the corresponding hydrolysis constants (Kh)i were calculated. An unusual decrease of ßi with increasing temperature has been discussed

scholarly journals DEVELOPMENT OF EXTRACTIVE SPECTROPHOTOMETRIC METHOD FOR THE DETERMINATION OF IRON (III) WITH SCHIFF BASE 2-[(2-HYDROXYPHENYLIMINO) METHYL]-4-NITROPHENOL

2016 ◽  
Vol 8 (4) ◽  
pp. 89 ◽  
Author(s):  
Datta B. Mandhare ◽  
Vasant D. Barhate
Keyword(s):  
Aqueous Solution ◽  
Schiff Base ◽  
Spectrophotometric Method ◽  
Molar Absorptivity ◽  
Maximum Absorption ◽  
Ratio Method ◽  
Pharmaceutical Samples ◽  
Mole Ratio Method ◽  
Ph Range

Objective: A simple spectrophotometric method has been developed for the determination of Iron (III) by using Schiff base 2-[(2-hydroxyphenylimino) methyl]-4-nitrophenol [HPIMNP].Methods: HPIMNP extracts Fe (III) quantitatively (99.95%) into chloroform from an aqueous solution of pH range 4.0-6.0.Results: The chloroform extracts show maximum absorption at 510 nm (λ max). Beer’s Law is obeyed over the Fe (III) concentration range of 0.5 to 20.0 µg/ml. The Molar absorptivity and Sandell’s sensitivity for Fe–HPIMNP system is 5000 L mol ˉ1 cmˉ1 and 0.011 µg cmˉ2respectively. The composition of extracted species is found to be 1: 3 [Fe-HPIMNP] by Job’s continuous variation and Mole-ratio method. Interference by various ions has been studied.Conclusion: The proposed method is rapid, sensitive, reproducible and accurate and it has been satisfactory applied for the determination of Iron in Pharmaceutical Samples.

Magnetophoretic Mole-Ratio Method

2017 ◽  
Vol 89 (19) ◽  
pp. 10141-10146 ◽  
Author(s):  
Hitoshi Watarai ◽  
Jiayue Chen
Keyword(s):  
Ratio Method ◽  
Mole Ratio Method
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