Solvation of inorganic complexes: transfer chemical potentials for mono- and bi-nuclear cobalt(III) complexes to methanol + water mixtures

Solubilities in MeOH--H₂O mixtures at 298.2 K are reported for a number of salts of mono- and bi-nuclear cobalt(III) complexes. From these solubilities and published single ion transfer chemical potentials, on the TPTB (Ph₄P⁺ = BPh^– ₄ ) assumption, transfer chemical potentials have been derived for these mono- and bi-nuclear cobalt(III) complexes. The results and trends are discussed in relation to those for other complexes and ions in these binary aqueous solvent mixtures.     

Transfer chemical potentials for iron(II)-diimine complexes from water into aqueous methanol

Summary Solubilities of perchlorate and thiocyanate salts of several iron(II)-diimine complexes of Schiff base ligands in methanolwater mixtures are reported. From these results and published values for transfer chemical potentials of the perchlorate and thiocyanate anions, transfer chemical potentials for the complex cations are calculated. Trends with solvent composition suggest that preferential solvation varies from negligible to very strongly by methanol, depending on the size and hydrophilic-hydrophobic character of the complex.On leave from the Faculty of Science, Sohag, Egypt.     

Solubilities and Transfer Chemical Potentials for Cobalt(III) Complexes in <Emphasis Type="BoldItalic">t</Emphasis>-butanol– <Emphasis Type="BoldItalic">i</Emphasis>-propanol–, and ethanol–water Mixtures

Solubilities in t-BuOH–, i-PrOH–, and EtOH–H₂O mixtures at 298.2 K are reported for a number of salts of mono- and bi-nuclear cobalt(III) complexes. From these solubilities and published single ion transfer chemical potentials, on the TATB (Ph₄As ⁺≡ BPh₄^-) assumption, transfer chemical potentials have been derived for most of these cobalt(III) complexes. The results and trends are discussed in relation to those for other ions and complexes. Effects of ligand nature for transfer to t-BuOH–H₂O mixtures are detailed and, for a selection of complexes, trends for transfer of a given complex to t-BuOH–, i-PrOH–, EtOH– , and MeOH– H₂O mixtures are compared.     

Kinetics of base hydrolysis of tris-(1,10-phenanthroline)iron(II) and of solvolysis of cis-dichlorobis(1,2-ethanediamine)cobalt(III) in water + diol mixtures

Rate constants for base hydrolysis of the tris-(1,10-phenanthroline)iron(II) cation and for solvolysis of the cis-dichlorobis(1,2-ethanediamine)cobalt(III) cation have been measured in binary aqueous mixtures containing 1,2-ethanediol, 1,2- or 1,4-butanediol, 1,2- or 1,6-hexanediol, 1-propanol, or t-butyl alcohol, at 298.2 K. Kinetics of base hydrolysis of the cobalt(III) complex have also been monitored in methanol-water and ethanol-water mixtures, again at 298.2 K. The observed reactivity trends are discussed in terms of the hydrophilic and hydrophobic properties of the respective diols. The dominant factor determining reactivity is hydration of the attacking hydroxide or leaving chloride, as is evidenced by the close correspondence between rate constants and transfer chemical potentials for these anions. The role of hydration has also been probed through the determination of activation volumes for these two reactions in 60% 1,4-butanediol. © 1993 John Wiley & Sons, Inc.     

Transfer chemical potentials for cobalt(III) and chromium(III) complexes from water into aqueous methanol; their relevance to reactivity trends for cobalt(III)-chloride aquation

Summary We report solubilities of a number of cobalt(III) and chromium(III) complex salts in methanol-water mixtures. From these, and published solubilities of salts of other complexes of these metals, we have calculated transfer chemical potentials from water into aqueous methanol for a variety of cationic and anionic complexes of cobalt(III) and chromium(III), using the assumption _m(Ph₄As⁺) + _m(BPh ₄ ^– ). The established trends are discussed in terms of electrostatic factors and of the hydrophilicity or hydrophobicity of the ligands present. The effects of single ion assumptions on conclusions of initial state-transition state analyses of solvent effects on reactivity are assessed with particular reference to aquation of thetrans-[Co(en)₂Cl₂]⁺ andtrans-[Co(py)₄Cl₂]⁺ cations.On leave from the Faculty of Science, Sohag, Egypt.     

SOLVATION OF ALUMINIUM(III) AND IRON(III) COMPLEXES OF HYDROXAMATE LIGANDS IN ALCOHOL-WATER MIXTURES

Abstract

Solubilities and derived transfer chemical potential trends are reported for several tris(hydroxamato)-aluminium(III) and iron(III) complexes in methanol-water and in t-butylalcohol-water solvent mixtures. These trends are discussed in terms of hydrophilic and hydrophobic characteristics of the peripheries of these complexes.     

Structure and solvation of an encapsulated iron(II) complex derived from cyclohexane-1,2-dione-dihydrazone and formaldehyde

Summary Reaction of iron(II) salts with cyclohexane-1,2-dione-dihydrazone and formaldehyde yields a complex containing encapsulated Fe²⁺, as shown by an x-ray diffraction structure determination of its hexafluorophosphate salt. Preferential solvation of this complex cation has been assessed through solubility measurements of this hexafluorophosphate salt in methanol-water mixtures. Transfer chemical potential trends for the complex cation and for the hexafluorophosphate anion are compared with those for other iron(II) complexes and for other simple anions respectively, and patterns of preferential solvation discussed.     

Medium effect in the base hydrolysis of pentaamminebromocobalt(III) ion

Summary The effect of organic cosolvent on the rate constant of the base hydrolysis of pentaamminebromocobalt(III) ion was investigated in mixtures of H₂O with MeOH, EtOH,i-PrOH,t-BuOH, and dioxane. The thermodynamic transfer functions, corresponding to the transfer of reactants and activated complex from water to the solvent mixtures, were evaluated from kinetic measurements and from solubilities of the complex salt. The experimental results are in good agreement with a dissociative mechanismvia the conjugate base.     

Polarographic analytical determination of Hg(II), Cu(II), Cd(II), As(III), Sb(III), Ti(IV) and U(VI) in the presence of Fe(III)

The analytical determination of Hg(II), Cu(II), Cd(II), As(III), Sb(III), Ti(IV) and U(VI) in the presence of Fe(III) and 1 M H₂SO₄ are investigated using the polarographic technique. The wave corresponding to the reduction of Fe(III) to Fe(II) was found to be completely suppressed by the addition of 1% pyrogallol. Thus, different mixtures of these elements, viz. Hg(II), Cu(II), Cd(II), As(III) and Fe(III)-mixture (A), Cu(II), Cd(II), Sb(III), As(III) and Fe(III)-mixture (B), and Cu(II), Cd(II), Ti(IV), U(VI) and Fe(III)-mixture (C), were quantitatively determined using 1% pyrogallol and 1 M H₂SO₄ as supporting electrolyte. The i₁/c results give excellent correlations in each case, as indicated from the results of leastsquares regression analysis.     

Electrochemistry of lanthanides in molten chloroaluminates: Part I. The electrochemical behaviour of Eu(III), Yb(III) and Sm(III)

The electrochemical behaviour of Eu(III), Yb(III,II) and Sm(III,II) has been investigated in NaCl-AlCl₃ mixtures, in a temperature range between 150 and 250°C. Principal investigation methods are cyclic voltammetry, pulse polarography and chronoamperometry. The three tervalent lanthanides can be reduced reversibly and solutions of divalent oxidation states are stable. E_1/2 potentials measured with respect to an Al electrode in a saturated melt are located respectively at 2.295 V (Eu), 1.630 V (Yb) and 1.080 V (Sm). In acidic chloroaluminates, the three investigated lanthanides are more oxidizing than in other more complexing solvents. If the acidity of the melt is decreased, precipitation of the trichloride (or the dichloride) occurs and the solubility product of the different species is directly related to the cationic size.     

Uncharged encapsulated iron(II) complexes: transfer chemical potentials and solvation in water-methanol and water-t-butanol mixtures

Summary Transfer chemical potentials have been determined from measured solubilities for four uncharged encapsulated iron(II) complexes containing three diimine ligating moieties and O₃BOBu-n and O₃BF capping groups, in H₂O–MeOH andt-BuOH–H₂O solvent mixtures, The trends in transfer chemical potentials are discussed in terms of the natures of the encapsulating ligands, and are compared with those for a selection of other iron(II)-diimine complexes.     

Electrochemical and electrocatalytic properties of meso-triphenylcorrole and its complexes with Mn(III), Co(III), Cu(III), and Zn(II)

The method of cyclic voltammetry (CV) was used to compare electrochemical and electrocatalytic properties of meso-triphenylcorrole [H₃(ms-Ph)₃Cor] and also its complexes with Mn(III), Co(III), Cu(III), and Zn(II) in 0.1M KOH. Metal-localized redox transitions are detected in the complexes of Mn (III ?? IV) and (III ?? II), Co (III ?? II), Cu (III ?? II). It is shown that the manganese complex features most effective catalytic properties in the reaction of molecular oxygen electroreduction.     

Organic acid solutions in the chromatography of inorganic ions VIII. Cation-exchange of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media

Summary The cation-exchange behaviour of Mn(II), Cd(II), Co(II), Ni(II), Zn(II), Cu(II), Fe(III), Sc(III), Y(III), Eu(III), Dy(III), Ho(III), Yb(III), Ti(IV) and Nb(V) in malate media at various concentrations and pH, was studied with Dowex 50 WX8 resin (200–400 mesh) in the ammonium form. Separation of Fe(III)/Cu(II), Fe(III)/Cu(II)/Zn(II), Fe(III)/Co(II)/Mn(II), Cu(II)/Ni(II)/Mn(II), Fe(III)/Cu(II)/Co(II)/Mn(II), Fe(III)/Cu(II)/Ni(II)/Cd(II), Yb(III)/Eu(III), Sc(III)/Y(III),Sc(III)/Yb(III)/Dy(III) and Nb(V)/Yb(III)/Ho(III) has been achieved, among others.This work was supported by C.N.R. of Italy.     

15N NMR coordination shifts in Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with pyridine, 2,2'-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2'-biquinoline, 2,2':6', 2'-terpyridine and their alkyl or aryl derivatives

The 15N NMR data for 105 complexes of Pd(II), Pt(II), Au(III), Co(III), Rh(III), Ir(III), Pd(IV), and Pt(IV) complexes with simple azines such as pyridine, 2,2'-bipyridine, 1,10-phenanthroline, quinoline, isoquinoline, 2,2'-biquinoline, 2,2':6', 2'-terpyridine and their alkyl or aryl derivatives have been reviewed. The 15N NMR coordination shifts, i.e. the differences between the 15N chemical shifts of the same nitrogen in the molecules of the complex and the ligand (Delta(15N) (coord) = delta(15N) (compl)--delta(15N) (lig)), have been related to some structural features of the reviewed coordination compounds, like the type of the central ion and the character of auxiliary ligands (mainly in trans position). These Delta(15N) (coord) parameters are negative, their absolute magnitudes (ca 30-150 ppm) generally increasing in the metal order Au(III) < Pd(II) < Pt(II) and Rh(III) < Co(III) < Pt(IV) < Ir(III), as well as with the enhanced trans influence of the other donor atoms (H, C < Cl < N).     

The state of Fe(III), Cr(III), Zr(IV), Y(III) radionuclides in solutions containing complexing anions

The states Fe(III), Cr(III), Zr(IV) and Y(III) in solutions in the presence of oxalate-, phosphate- and EhDTA anions has been investigated with the help of ultrafiltration, dialysis, centrifugation, adsorption methods and migration in an electric field. The influence of complexing anions on the state of the radionuclides in solutions in discussed.     

Ion Association Between Hexaamminecobalt (III) Ion and Monovalent Anions in Methanol-Water Mixtures from 10 to 50°C

The conductivities of chloride, bromide, iodide, nitrate, and perchlorate of hexaamminecobalt(III) complex were measured in 10-80 wt.% methanol-water mixtures at varying temperatures from 10 to 50°C. The ion association constants were estimated by analyzing conductivity data in terms of the Robinson-Stokes equations. Ion-association constants calculated for all complex salts in methanol-water mixtures increased, depending on the percentage of methanol. This was equivalent to the ion-association constants increasing with a decrease in the the dielectric constant of the mixtures. K _A values increased with increasing temperature for the chloride, bromide, and iodide of [Co(NH₃)₆]³⁺. It was observed that these values indicated some disorder, dependent on the temperature, for nitrate and perchlorate. Thermodynamic parameters (Gibbs' free energy, entropy and enthalpy of ion association) were estimated from the temperature dependence of the ion-association constant. The limiting molar conductivities of complex ion and monovalent anions in the mixed solvents were determined from our experimental data by using the Kohlraush equation.     

Electrochemical reduction of the lanthanide ions: Part II. Second reduction step of europium(III), ytterbium(III) and samarium(III) in acidic tetramethylammonium perchlorate solution

The second reduction step of Eu(III), Yb(III) and Sm(III) in 0.04 M tetramethylammonium perchlorate in the pH range 1.8–7 was investigated by cyclic voltammetry and d.c. polarography. The proposed reaction scheme at large hydrogen ion/lanthanide ion concentration ratios involves the reduction of the lanthanide(II) ion to the metallic state accompanied by a surface catalytic reaction in which the reactant is regenerated and also hydroxyl ions are formed which induces the precipitation of lanthanide(II) hydrous oxide on the electrode surface. This lanthanide(II) hydroxide is reduced at more negative potentials than the hydrated lanthanide(II) species. At lower hydrogen ion/lanthanide ion concentration ratios a preceding chemical reaction, probably involving hydrolyzed lanthanide(II) species, becomes rate determining.     

Salisaldehyde-2-aminobenzimidazole schiff base complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II)

New metal complexes of Fe(III), Co(II), Ni(II), Cu(II), Zn(II) and Cd(II) with salicylidine-2-aminobenzimidazole (SABI) are synthesized and their physicochemical properties are investigated using elemental and thermal analyses, IR, conductometric, solid reflectance and magnetic susceptibility measurements. The base reacts with these metal ions to give 1:1 (Metal:SABI) complexes; in cases of Fe(III), Co(II), Cu(II), Zn(II) and Cd(II) ions; and 1:2 (Metal:SABI) complexes; in case of Ni(II) ion. The conductance data reveal that Fe(III) complex is 2:1 electrolyte, Co(II) is 1:2 electrolyte, Cu(II), Zn(II) and Cd(II) complexes are 1:1 electrolytes while Ni(II) is non-electrolyte. IR spectra showed that the ligand is coordinated to the metal ions in a terdentate mannar with O, N, N donor sites of the phenloic -OH, azomethine -N and benzimidazole -N3. Magnetic and solid reflectance spectra are used to infer the coordinating capacity of the ligand and the geometrical structure of these complexes. The thermal decomposition of the complexes is studied and indicates that not only the coordinated and/or crystallization water is lost but also that the decomposition of the ligand from the complexes is necessary to interpret the successive mass loss. Different thermodynamic activation parameters are also reported, using Coats-Redfern method. This revised version was published online in July 2006 with corrections to the Cover Date.     

Efficiency and application of poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber for pre-concentrating and separating trace Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) from solution samples

Poly(acryldinitrophenylamidrazone-dinitroacrylphenylhydrazine) chelating fiber was synthesized from polyacrylonitrile fiber and used for enrichment and separation for traces of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions from solution samples. The acidity, rate, re-use, capacity and interference on the adsorption of ions on the chelating fiber as well as the conditions of desorption of these ions from the chelating fiber were investigated by means of inductively coupled plasma optical emission spectrometry. The results show that 10-100 ngml(-1) of Au(III), Ru(III), In(III), Bi(III), Zr(IV), V(V), Ga(III) and Ti(IV) ions can be quantitatively enriched by the chelating fiber at a 2 mlmin(-1) of flow rate in the range pH 4-5, and desorbed quantitatively with 20 ml of 5 M HCl for In(III), Bi(III), Zr(IV), V(V), Ga(III), Ti(IV) and 20 ml of 4 M HCl+2% CS(NH(2))(2) solution for Au(III), Ru(III) (with recovery>95%). 50- to 500- fold excesses of Fe(III), Al(III), Mg(II), Mn(II), Ca(II), Cu(II), Ni(II) ions cause little interference in the concentration and determination of analyzed ions. When the fiber was reused for 8 times, the recoveries of the above ions enriched by the fiber were still over 87%. The relative standard deviations (RSDs) for the enrichment and determination of 10 ngml(-1) Au, Ru, In, Bi, Ga and 1 ngml(-1) Zr, V, Ti were lower than 3.0%. The results obtained for these ions in real solution samples by this method were basically in agreement with the given values with average errors of less than 6.3%. FT-IR spectra show that existence of NNCNHNH, OCNHNH and NO(2) functional groups are verified in chelating fiber, and Au(III) or Ru(III) is mainly combined with nitrogen (or oxygen) of the groups to form a chelate complex.     

Physicochemical,spectroscopic, and anti-tumor studies of cefradine complexes with Ca(II), Zn(II), Fe(III), Au(III), and Pd(II) ions

Russian Journal of General Chemistry - Five new cefradine (Cef) drug complexes were synthesized by 1 : 1 chemical reactions with Ca(II), Zn(II), Fe(III), Au(III), and Pd(II) ions in alkaline...