Oxalato Complexes Research Articles

The configuration of the Cr(ox)(trien)+ cation

On the basis of the inversion reaction Λ-(+)589-Cr(ox)(trien)+ + HCl → Δ-(-)589cis-α-CrCl2(trien)+ the oxalato complex is now believed to have the cis-β configuration, rather than the previously suggested cis-α.

Thermal reactivity of metal oxalate hydrazinates

Metl oxalate hydrazinates MC 2O 4·2 N 2H 4 where MMg, Mn, Fe, Co, Ni, Cu, Zn and Cd have been prepared and characterised by chemical analysis and infrared spectra. Thermal reactivity and decomposition of these oxalato complexes have been studied using thermogravimetry and differential thermal analysis. Hydrazinates of Mn, Fe, Co, Ni and Cu oxalates exhibit autocatalytic decomposition behaviour whereas the others do not. This phenomenon can be attributed to the presence of a bridged hydrazine as well as the thermal stability of the anhydrous metal oxalates.

Kinetics of reduction of Co(NH3)4C2O4+ by oxalato complexes of titanium(III)

Kinetics of reduction of Co(NH3)4C2O4+ by oxalato complexes of titanium(III)

Evidence of iron(III)-oxalato complex formation in aqueous solution from x-ray diffraction

An aqueous solution of ferric ammonium oxalate has been examined to provide direct experimental evidence of complex formation between iron(III) and a typical organic complexing ligand. The radial distribution function as well as analysis of the structure function lead to the conclusion that the dominant species present in solution is the trioxalato-iron(III) complex in which each oxalate ion occupies two corners of a distorted octahedron around the Fe 3+ ions.

Kinetics and mechanism of base hydrolysis of cisα-oxalato(amine)(trien)cobalt(III) and salicylato(amine)(trien)cobalt(III)cations

Oxalato(amine)(trien)cobalt(III) and salicylato(amine)(trien)cobalt(III) perchlorates have been synthesized and tentatively assigned a cis α configuration. The dissociation constants of the complexes have been determined. The base hydrolysis of the complexes have been investigated at 30, 35, 38.6°C and I = 1.0 mol dm −3. The rate laws for the oxalato and salicylato complexes are −dln[Complex] T/dt = k 2[OH −] and −dln[Complex] T = k 1 + k 2[OH −] respectively. For the oxalato complex, k 2(30°C) = (2.95 ± 0.05) × 10 −2 dm 3 mol −1 s −1, ΔH ∗ = (109 ± 4) KJ mol −1, ΔS ∗ = (85 ± 13) JK −1 mol −1 and for the salicylato complex, k 1(30°C) = (1.58 ± 0.28) × 10 −4 s −1, ΔH ∗ = (166 ± 7) KJ mol −1, ΔS ∗ = (229 ± 21) JK −1 mol −1 and k 2(30°C) = (3.56 ± 0.10) × 10 −3 dm 3 mol −1 s −1, ΔH ∗ = (101 ± 6) KJ mol −1, ΔS ∗ = (42 ± 20) JK −1 mol −1. The base hydrolysis reactions of the complexes were followed in presence of imidazole and ethanolamine, in the presence of added anions and also in D 2O medium. The results are discussed in terms of δ SN 1CB mechanism involving rate limiting CoO bond fission for both k 1 and k 2 paths. However, the possibility of CO bond cleavage in the base hydrolysis of the oxalato complex is not ruled out.

Solid state photochemistry and photochromism of oxalato complexes of molybdenum(VI)

Solid state photochemistry and photochromism of oxalato complexes of molybdenum(VI)

The trans-cis Isomerization of the Diaquabis(malonato)chromate(III) Ion in Various Organic Solvent–Water Mixtures

Abstract The kinetics of the trans-cis isomerization of [Cr(mal)2(H2O)2]− have been investigated in binary mixed solvents, including methanol-, ethanol-, dioxane-, and acetone-water mixtures. The first-order rate constant increases with a decrease in the volume percentage of the water, but is independent of the kind of organic solvent. The rate is not affected by the addition of any cation to an aqueous solution. These results are in contrast to those for the analogous oxalato complex, and are interpreted in terms of a dissociation mechanism in which the rate-determining step is the dissociation of the coordinating water molecule.

Photolysis of copper(II) oxalato complexes in aqueous solution. Identification and reactions of an intermediate

The intermediate responsible for the transient absorption band (λmax= 385 nm), produced by flash photolysis of copper(II) oxalato complexes in deaerated aqueous solution, is identified as CuCO2 by comparison with an apparently identical species formed by reaction of CuI ions with ·CO–2 radicals in the pulse radiolysis of the CuII/oxalate/formate system. CuCO2 decays by first-order kinetics with the rate constant dependent on pH, CuII and oxalate ion concentrations. The decay kinetics are explained by two competing reactions of CuCO2: (a) protonolysis to CuII and HCO2H, (b) reaction with CuII to give CuI and CO2.

ChemInform Abstract: SUBSTITUTION REACTIONS OF OXALATO COMPLEX IONS. 12. KINETICS OF THE ANATION OF DIAQUOBIS(ETHYLENEDIAMINE)COBALT(III) ION BY OXALATE IN AQUEOUS ACIDIC SOLUTION. NITRATE ION CATALYSIS OF A COBALT(III) SUBSTITUTION REACTION

Chemischer InformationsdienstVolume 10, Issue 42 Organoelement Compounds ChemInform Abstract: SUBSTITUTION REACTIONS OF OXALATO COMPLEX IONS. 12. KINETICS OF THE ANATION OF DIAQUOBIS(ETHYLENEDIAMINE)COBALT(III) ION BY OXALATE IN AQUEOUS ACIDIC SOLUTION. NITRATE ION CATALYSIS OF A COBALT(III) SUBSTITUTION REACTION R. VAN ELDIK, R. VAN ELDIKSearch for more papers by this authorG. M. HARRIS, G. M. HARRISSearch for more papers by this author R. VAN ELDIK, R. VAN ELDIKSearch for more papers by this authorG. M. HARRIS, G. M. HARRISSearch for more papers by this author First published: October 16, 1979 https://doi.org/10.1002/chin.197942324Read the full textAboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume10, Issue42October 16, 1979 RelatedInformation

Substitution reactions of oxalato complex ions. 12. Kinetics of the anation of diaquobis(ethylenediamine)cobalt(III) ion by oxalate in aqueous acidic solution. Nitrate ion catalysis of a cobalt(III) substitution reaction

Substitution reactions of oxalato complex ions. 12. Kinetics of the anation of diaquobis(ethylenediamine)cobalt(III) ion by oxalate in aqueous acidic solution. Nitrate ion catalysis of a cobalt(III) substitution reaction

Precipitation of Thorium or Uranium(VI) Complex Ion with Cobalt(III) or Chromium(III) Complex Cation, (III)

Chloride ion (foreign ion) effect on the precipitation of thorium or uranium (VI) sulfato, carbonato and oxalato complex ions has been studied. The results are in correlation with the chemical species present in the solution. The precipitation of highly-charged complex ions is affected by chloride ion and the precipitation yield decreases with chloride salt concentration. The precipitation of sulfato complex ion shows only slight dependency on the chloride salt concentration because of the absence of highly-charged sulfato complex ion under the experimental conditions.

Precipitation of Thorium or Uranium(VI) Complex Ion with Cobalt(III) or Chromium(III) Complex Cation, (III)

Chloride ion (foreign ion) effect on the precipitation of thorium or uranium (VI) sulfato, carbonato and oxalato complex ions has been studied. The results are in correlation with the chemical species present in the solution. The precipitation of highly-charged complex ions is affected by chloride ion and the precipitation yield decreases with chloride salt concentration. The precipitation of sulfato complex ion shows only slight dependency on the chloride salt concentration because of the absence of highly-charged sulfato complex ion under the experimental conditions.

Photochemical separation of metals in aqueous solution

Several d-block transition elements have been separated from mixtures by photochemical means, using lines from various lasers. The species involved, oxalato complexes of Fe and Co, exhibit selective photoreduction following absorption in bands in the visible and near ultraviolet regions of the spectrum. This experiment is apparently the first demonstration of selective laser photochemistry in liquid phase mixtures of chemically related elements.

Volumes of activation for intramolecular racemization mechanisms. High-pressure racemization of bipyridyl, phenanthroline and oxalato complexes of chromium(III) in solution

Volumes of activation for intramolecular racemization mechanisms. High-pressure racemization of bipyridyl, phenanthroline and oxalato complexes of chromium(III) in solution

Alkaline salts of oxalato titanate(IV) complexes. Part 1. Syntheses and characterizations

Alkaline salts of Ti(IV) oxalato complexes M 2[TiO(C 2O 4) 2] ·nH 2O, where M = Li, Na, K, Rb, Cs, have been synthesized. These compounds have been characterized by chemical analyses, infrared spectroscopy and X-ray diffraction. Li 2[TiO(C 2O 4) 2] ·4H 2O has a tetragonal unit cell of dimensions a = b = 14.27(1), c = 11.96(1) Å and the space group is P4 2/n. K 2[TiO(C 2O 4) 2] ·2H 2O has a triclinic unit cell: a = 9.861(5), b = 11.085(6), c = 11.768(7) Å, α = 68.21(4), β = 85.15(4), γ = 76.37(4)° and the space group is P1. For Na 2[TiO(C 2O 4) 2] ·3H 2O, a = 8.98(1), b = 11.04(1), c = 11.51(1) Å, α = 66.1(1)°, β = 84.5(1), γ = 77.8(1)°. For Rb 2[TiO(C 2O 4) 2]· H 2O, a = 10.43(1), b = 11.15(1), c = 11.54(1) Å, α = 69.9(1), β = 84.5(1), γ = 75.5(1)°. Finally for Cs 2[TiO(C 2O 4) 2] ·H 2O, a = 10.89(1), b = 11.62(1), c = 12.00(1) Å, α = 68.2(1), β = 85.2(1), γ = 76.0(1)°. The infrared bands have been assigned by analogy with the assignment of a trisoxalato Cr(III) complex.

The oxalato complexes of titanium(IV)—II: Precipitation with lead(II) in 0.5 M NaClO 4 solution

Titration studies of ammonium titanyl oxalate solutions with Pb(NO 3) 2 at an ionic strength of 0.5 M (NaClO 4) have shown that at pH > 1.5 precipitates are formed consisting of three compounds: PbTiO(C 2O 4) 2·4H 2O, PbC 2O 4 and Ti(OH) 4. The solubility product of lead titanyl oxalate (PTO) is (35 ± 2) times the solubility product of lead oxalate, i.e. log K PTO = −6.90 ± 0.03, when log K PO = −8.45 for lead oxalate as found by Klatt. The solubility product [Ti(OH) 2 2+][OH −] 2 was found to have the value log K TH = −30.5 ± 0.25. At low pH lead oxalate and titanium hydroxide dissolve. It is necessary to include a lead titanyl complex of unknown nature in calculation models for simulating equilibrium concentrations during titrations in order to explain the anomalously high dissolved lead(II) concentration. The solubility product calculated for PTO is not very sensitive to the different models. Lead and titanium contents of solutions equilibrated with solid PTO differed from the expected values based on the models for titrations. A satisfactory explanation for the low Ti(IV) and high Pb(II) concentrations can not yet be given.

Observations on the spectra and structures of seven-and eight-co-ordinate oxalato complexes of titanium(III)

Observations on the spectra and structures of seven-and eight-co-ordinate oxalato complexes of titanium(III)

The oxalato complexes of titanium(IV)—I: Mononuclear Ti(OH) 2(C 2O 4) 22− in solution

Molecular weight, electrodialysis and anion exchange measurements between pH 1 and 4 showed that the titanyl oxalate anion is present in solution as mononuclear Ti(OH) 2(C 2O 4) 2 2 units. pH studies of solutions of (NH 4) 2TiO(C 2O 4) 2·H 2O in 0.5 M NaClO 4 medium and computer evaluation and simulation by LETAGROP and HALTAFALL showed that the behaviour of such solutions can be simulated by applying stability constants of log β 1 = 7.90 ± 0.02 and log β 2 = 13.24 ± 0.07, when using hydrolysis constants given by Nazarenko et al. In an attempt to determine the stability constant β 2 spectrophotometrically using an exchange method with pyrocatechol, a mixed ligand complex was found with a Ti:pyrocatechol:oxalate ratio of 1 : 1 : 1.

Preparation and properties of some non-ionic bis(ethylenediamine)cobalt(III) complexes containing unidentate oxalato ligands

Unidentate oxalato complexes cis-[Coen 2(X)(C 2O 4)] where X = OH, Cl and Br are prepared and characterised. The kinetics of anation of [Coen 2(OH)(OH 2)] 2+ by C nH 2n(COO) 2− 2 are reported for n = 0–8 and the mechanism of the reaction is briefly discussed.

Substitution Reactions of Oxalato Complex Ions. XI. Kinetics of the Anation of Aquopentaamminecobalt(III) Ion by Oxalate in Aqueous Acidic Solution

Substitution Reactions of Oxalato Complex Ions. XI. Kinetics of the Anation of Aquopentaamminecobalt(III) Ion by Oxalate in Aqueous Acidic Solution