Extraction of thorium from aqueous nitric acid solution by bis-2-(butoxyethyl ether) (DBC)

The solvent extraction of thorium(IV) (4.3·10^–4M) from nitric acid solution by bis-2-(butoxyethyl ether) (butex or DBC) has been studied. It has been investigated as a function of nitric acid, extractant and metal ion concentration. The effect of equilibration time, diverse ions and salting-out agent on the extraction has also been examined. Among anions, fluoride, phosphate, oxalate and perchlorate have reduced the extraction. Cations such as Na(I), K(I), Ca(II), Zn(II), Al(III), Ti(IV), Zr(IV) except Sr(II) and Pb(II) do not interfere in the extraction. The extraction is enhanced upto 97% in three stages at 6M HNO₃ having 2.94M NaNO₃ as salting-out agent. The extraction is found to be independent of thorium concentration in the range studied (4.3·10^–4–4.3·10^–2M). The temperature (18–45°C) has an adverse effect on the extraction. A 1% solution of ammonium bifluoride is found to be a good stripping solution and recovery of thorium is >98%.     

A novel three-dimensional mixed bridging–ligand complex with an unexpected 1,3-diaminopropane bridge

Reaction of K₃[Fe(CN)₆] with [Cu(tn)₂](ClO₄)₂ (tn=1,3-diaminopropane) leads to a novel mixed cyano and tn bridged three-dimensional (3D) bimetallic assembly (1), in which each [Fe(CN)₆]⁴⁻ anion connects six copper(II) cations via six CN⁻ groups, whereas each copper(II) cation is linked to three [Fe(CN)₆]⁴⁻ ions and two other copper(II) ions through Cu–NC–Fe and Cu–tn–Cu linkages, respectively. Magnetic studies reveal weak antiferromagnetic interactions between the nearest Cu^II (S=1/2) ions through the diamagnetic [Fe(CN)₆]⁴⁻ anion.     

Adsorption of traces of hafnium on manganese dioxide from acid solutions

Adsorption of hafnium on manganese dioxide from nitric and perchloric acid solutions has been studied and optimized with respect to shaking time, concentration of acid, oxide and metal. Maximum adsorption has been noticed from 0.1 mol · dm^–3 acid solutions in 20 minutes around 10^–5 mol · dm^–3 hafnium concentration. The adsorption of hafnium follows a Freundlich adsorption isotherm. Oxalate, thiosulfate, Na(I) and Al(III) from nitric acid and K(I) and Zn(II) from perchloric acid increase the adsorption, whereas all other anions and cations tested reduce the adsorption from both media Fe(III) and Sn(IV) significantly. Zn(II) and Co(II) show low adsorption affinity.     

Mechanistic aspects of the reduction of ruthenium(III) catalyzed

The kinetics of Ru_III catalyzed reduction of hexacyanoferrate(III) [Fe(CN)₆]^3–, by atenolol in alkaline medium at constant ionic strength (0.80 mol dm^–3) has been studied spectrophotometrically, using a rapid kinetic accessory. The reaction between atenolol and [Fe(CN)₆]^3– in alkaline medium exhibits 1:2 stoichiometry [atenolol:Fe(CN)₆ ^3–]. The reaction showed first order kinetics in [Fe(CN)₆]^3– concentration and apparent less than unit order dependence, each in atenolol and alkali concentrations. Effect of added products, ionic strength and dielectric constant of the reaction medium have been investigated. A retarding effect was observed by one of the products i.e., hexacyanoferrate(II). The main products were identified by i.r., n.m.r., fluorimetric and mass spectral studies. A mechanism involving the formation of a complex between the atenolol and the hydroxylated species of ruthenium(III) has been proposed. The active species of oxidant and catalyst were [Fe(CN)₆]^3–and [Ru (H₂O)₅OH]²⁺, respectively. The reaction constants involved in the mechanism were evaluated. The activation parameters were computed with respect to the slow step of the mechanism, and discussed.     

Thermal and photochemical interaction of octacyanometallates(IV), [M(CN)8]4− (M = Mo or W) in the presence of pyrazine

The interactions between [M(CN)₈]^4– (M = Mo or W) and pyrazine (pz) in the solid state and in aqueous solutions have been analysed. In strongly acidic solutions {pzH⁺, [M(CN)₈]^4–} ion pair formation is observed; the pyrazinium salts (pzH)₂(H₃O)₂[Mo(CN)₈]·0.5pz·3H₂O and (pzH)₂K(H₃O)[W(CN)₈]·H₂O have been isolated. The X-ray crystal structure of the latter, and the spectroscopic properties of both, are described. The [W(CN)₈]^4– anion is approximately square antiprismatic (D_4d), with different H-bond environments around the N atoms. The ligand-field photolysis of [M(CN)₈]^4– in the presence of pyrazine in neutral and alkaline solution results in the formation of tetracyanooxometallates(IV) in equilibrium with pentacyanooxometallates(IV) through the [M(CN)₇(pz)]^3– anions as intermediates. The formation of the [M(CN)₆(pz)₂]^2– ion, postulated in the literature to be the final product of the alkaline photolysis, has definitively been excluded.     

Determination of Selenium(IV) by Stripping Voltammetry at a Mercury-Film Electrode

A procedure was proposed for the determination of selenium(IV) by stripping voltammetry on a mercury-film electrode at an electrolysis potential of +0.4 V versus the saturated silver–silver chloride reference electrode in a 1 M H₂SO₄ solution. The current of the cathodic peak is a linear function of the selenium(IV) concentration in the range from 5 × 10^–3 to 3 × 10^–1 mg/L (6.3 × 10^–8 to 3.8 × 10^–6 M) at a time of electrolysis of 30 s (t _el). The detection limit for selenium is 1 × 10^–4 mg/L (1.3 × 10^–9 M) at t _el = 300 s. It was shown that selenium(IV) can be determined in the presence of 10 mg/L Zn(II), 1 mg/L Cd(II), 0.5 mg/L Pb(II), and 0.2 mg/L Cu(II). A procedure for the determination of selenium in natural, mineral, and potable water was proposed.     

Metal complexes of 6-chloropurine

Summary Five Cu(II), Pd(II), Cd(II), Pt(IV), and Au(III) complexes of 6-chloropurine have been obtained. The complexes were characterized by elemental analysis, IR,¹H-NMR and¹³C-NMR spectroscopy. On the basis of these data the structure of the complexes and the coordination of the ligand have been proposed. Thus, the physical and chemical methods supported evidence that in acidic medium, with exception of the Cu(II) complex, 6-chloropurine acts in the monoprotonated form neutralizing the charge of [PdCl₄]^2–, [CdCl₄]^2–, [AuCl₄]^– and [PtCl₆]^2– anions. The thermal behaviour of the complexes has also been studied.

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Metallkomplexe von 6-Chlorpurin

Zusammenfassung Es wurden fünf Komplexe von 6-Chlorpurin mit Cu(II), Pd(II), Cd(II), Pt(IV) und Au(III) erhalten. Die Komplexe wurden mittels Elementaranalysen, IR,¹H-NMR und¹³C-NMR charakterisiert. Auf der Basis dieser Daten wurde eine Komplexstruktur und eine bestimmte Koordination der Liganden vorgeschlagen. Physikalische und chemische Methoden beweisen, daß im sauren Bereich [mit der Ausnahme von Cu(II)] das 6-Chlorpurin in der monoprotonierten Form koordiniert, wobei die Ladung von [PdCl₄]^2–, [CdCl₄]^2–, [AuCl₄]^– und [PtCl₆]^2– jeweils neutralisiert wird. Das thermische Verhalten der Komplexe wurde ebenfalls untersucht.

     

Equilibria in complexes of N-heterocyclic molecules,part XXI. Kinetics of reaction of hydroxide with bis [2,4,6-tri (2-pyridyl)-1,3,5-triazine] iron (II) and ruthenium(II)

Summary The kinetics of reaction of HO^– with [Ru(TPT)₂]²⁺ and [Fe(TPT)₂]²⁺ have been studied in detail. The former participates in an equilibrium with HO^– yielding a pseudo-base by attack at the ligand and, at very high concentrations of HO^–, dissociates to yield pure TPT quantitatively. [Fe(TPT)₂]²⁺ dissociates rapidly in basic solution, even at 273 K, however, [Fe(TPT)(TPT · OH)]+ does in fact exist and the Fell and Ru^ll reactions are quite similar, although that of Fell is much faster. The implications of these findings for the dissociation of [Fe(TPT)₂]²⁺ over a wide range of pH are discussed.Patt XX, ref. 1.     

Synergistic extraction of cobalt(II) with oxine/decanoic acid solution mixtures in benzene and chloroform

Synergistic extraction of Co(II) with 8-hydroxyquinoline (Hq)/decanoic acid [(HR)₂] solution mixtures in benzene and chloroform was carried out at 25°C. The aqueous ionic strength and the total concentration of cobalt(II) were 0.1 (NaCl) and 1·10^–5–1·10^–3M, respectively. The synergistic effect is interpreted by the formation of the mixed ligand ion-pair complexes: [(Coq(Hq)₂(HR))⁺, R^–] and [(Coq(Hq)₂(HR)₃)⁺, R^–] in benzene and chloroform, respectively.     

Extrahierte Verbindungen von Gallium, Indium und Thallium in Verteilungssystemen mit Tributylphosphat, Cyclohexanon und Isobutylmethylketon

Zusammenfassung Das Verteilungsverhalten der Halogenide und Halogenometallate von Gallium, Indium und Thallium mit den drei Solventien (S) Tributylphosphat (TBP), Cyclohexanon (Cyclo) und Isobutylmethylketon (IBMK) wurde untersucht. Die extrahierten Verbindungen wurden nach der Geradenmethode nach Asmus, der logarithmischen Methode nach McKay, der Methode der kontinuierlichen Variation, durch Analyse der beiden Phasen und durch konduktometrische Extraktionstitration nachgewiesen. Identifiziert wurden folgende Verbindungen: [GaCl₄]^–·2 S, Ga-(SCN) ₃·3 TBP, [Ga(SCN)₄]^–·2 TBP, [InCl₄]^–·2 TBP, [InBr₄]^–·2TBP, [InBr₄]·x Cyclo, [InBr₄]^–·x IBMK, [InJ₄]^–·2 S, In(SCN)₃·3 TBP, [In(SCN)₄]^–·2 TBP, TlCl₃·1 TBP, [TlCl₄]^–·2 S, TlBr₃·1 TBP, [Tl-Br₄] ^–·2 S, TlJ₃·x TBP und [TlJ₄]^–·xS. Wegen der nicht eindeutig definierten Oxydationsstufe von Thalliumjodiden ergaben sich bei den Versuchen experimentelle Schwierigkeiten. Daher wurde in diesem System zusätzlich das radioaktive Isotop ²⁰⁴Thallium verwendet.

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Extracted compounds of gallium, indium and thallium in distribution systems with tributyl phosphate, cyclohexanone and isobutylmethylketone

The behaviour of distribution of the halides and halogenometallates of gallium, indium and thallium with the three solvents (S) tributylphosphate (TBP), cyclohexanone (Cyclo) and isobutylmethylketone (IBMK) are investigated. The extracted compounds are detected with the straight-line method of Asmus, the logarithmic method of McKay, the method of continuous variation, by analysis of the two phases, and with the conductometric extraction-titration. The following compounds were identified: [GaCl₄]^–·2S, Ga(SCN)₃·3TBP, [Ga(SCN)₄]^–·2TBP, [InCl₄]^–·2TBP, [InBr₄]^–·2TBP, [InBr₄]·x Cyclo, [InBr₄]^–·x IBMK, [InJ₄]^– ·2S, In(SCN)₃·3TBP, [In(SCN)₄]^–·2TBP, TlCl₃·1TBP, [TlCl₄]^–·2S, TlBr₃ ·1TBP, [TlBr₄]^–·2S, TlJ₃·x TBP and [TlJ₄]^–·x S. The not unequivocally defined stage of oxidation of thallium iodides resulted in experimental difficulties. Thus, in this system the radioactive isotope ²⁰⁴thallium was additionally used.

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Herrn Professor Dr. E. Asmus zum 60. Geburtstag gewidmet.

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Wie danken Herrn Priv.-Doz. Dr. H. Nickel für die freundliche Unterstützung bei den in der KFA Jülich durchgeführten radioaktiven Messungen.     

Mechanochemical Reaction of 1,10-Phenanthroline with Metallic Iron

Fe(II) complex is isolated from the products of mechanical activation of a mixture of the powdered carbonyl Fe and 1,10-phenanthroline. According to the data of elemental analysis, an electronic absorption spectra, magnetochemical and EPR studies, the isolated compound is [FePhen₃]²⁺ Phen^–OH^– · 3H₂O that contains Phen^– radical-anion.     

Reactions of carbonate radical with cobalt(II) aminopolycarboxylates

Reactions of carbonate (CO ₃ ^–· ) and bicarbonate (HCO ₃ ^· ) radicals generated by photolysis of a carbonate or bicarbonate solution at pH 11.2 and 8.5, respectively, with Co(II) complexes of iminodiacetic acid (IDA) and ethylenediaminetetraacetic acid (EDTA) have been studied. The rate constants for the reactions were in the order of 10⁶–10⁷ dm³mol^–1s^–1. From the time-resolved spectroscopy of the products formed after reaction of CO _3· ^–· or HCO ₃ ^· , it is observed that CO ₃ ^–· or HCO ₃ ^· oxidize the metal center to its higher oxidation state.     

Cyclization and rearrangement of diterpenoids. II. Cyclization of cis-labda-8,13-dien-15-ol by the complex of titanium tetrachloride with N-methylaniline

It has been shown that the product of the reaction of cis-labda-8,13-dien-15-ol (I) with the complex of TiCl₄ (II) and PhNHCH₃ (III) is (1R,2R,7S,10S,12S,13S)-13-chloro-2,6,6,10,12-pentamethyltetracyclo[10.2.1.0^1,10·0^2,7]eicosane (IV), the formation of which gives information on the transformation of labdane diterpenoids into tetracycloeicosane derivatives. The reduction of (IV) with LiAH₄·CoCl₂ gave the corresponding hydrocarbon. It has been shown that (IV) is formed by the reaction of 13-hydroxy-2,6,6,10,12-pentamethyltetracyclo[10.2.1.0^1,10·0^2,7]eicosane with SOCl₂ and ZnCl₂. The characteristics of its IR, mass and NMR spectra are given.Institute of Chemistry of the Academy of Sciences of the Moldavian SSR, Kishinev. Translated from Khimiya Prirodnykh Soedinenii, No. 3, pp. 318–322, May–June, 1984.     

Photolysis of [PtBr6]2– complex in frozen methanol matrix

Photochemistry of the [PtBr₆]^2– complex in the low-temperature methanol matrix (77 K) was studied by low-temperature spectrophotometry and ESR spectroscopy. The [PtBr₄]^2– complex is the main photolysis product. The mechanism of two-electron reduction of the platinum(IV) ion is proposed. The primary photochemical process is electron transfer from the solvent molecule to the photoexcited initial complex to form the intermediate radical complex ([PtBr₆]^3–...^·CH₂OH). The transfer of the second electron in the radical complex produces the final reaction products.     

One electron oxidation of Ni(II)-iminodiacetate by carbonate radical

Reactions of carbonate radical (CO₃ ^–), generated by photolysis or by radiolysis of a carbonate solution with nickel(II)-iminodiacetate (Ni(II)IDA) were studied at pH 10.5 and ionic strength (I)==0.2 mol·dm^–3. The stable product arising from the ligand degradation in the complex is mainly glyxalic acid. Time-resolved spectroscopy and transient kinetics were studied using flash photolysis. From the kinetic data it was suggested that the carbonate radical initially reacts with Ni(III)IDA with a rate constant (2.4±0.4)·10⁶ dm³·mol^–1·s^–1 to form a Ni(II)IDA species which, however, undergoes a first-order transformation (k=2.7·10²·s^–1) to give a radical intermediate of the type Ni(II)RNHCHCO ₂ ^– ) which rapidly forms an adduct containing a Ni–C bond. This adduct decays very slowly to give rise to glyoxalic acid. From a consideration of equilibrium between Ni(II)IDA and Ni(III)IDA, the one electron reduction potential for the Ni(III)IDA/Ni(II)IDA couple was determined to be 1.467 V.     

Azido-, Rhodano-, Cyano- und Fluorokomplexe des Fe(III)-Ions in Dimethylsulfoxid

Zusammenfassung Auf Grund spektrophotometrischer und konduktometrischer Messungen wurden folgende Koordinationsformen des Eisen(III)-ions mit Azid-, Rhodanid-, Cyanid- und Fluoridionen in Dimethylsulfoxid festgestellt: [Fe(N₃)₄]^–, [Fe(SCN)₆]^3–, [Fe(CN)₂]⁺, Fe(CN)₃, [Fe(CN)₄]^–, [FeF₂]⁺, [FeF₄]^–.

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By means of spectrophotometric and conductometric measurements the following coordination forms of iron(III) with azide-, thiocyanate-, cyanide- and fluoride ions were found in dimethyl sulfoxide: [Fe(N₃)₄]^–, [Fe(SCN)₆]^3–, [Fe(CN)₂]⁺, Fe(CN)₃, [Fe(CN)₄]^–, [FeF₂]⁺, [FeF₄]^–.

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Mit 4 Abbildungen     

On the characteristics and mechanism of the radiation-induced chain reaction between sulfur dioxide and molecular oxygen in acid solutions

Characteristics of the -induced chain reaction between sulfur dioxide and molecular oxygen in perchloric and sulfuric acid media in the presence of Ce(III) ions have been studied. The concentration effects of dissolved oxygen (0.2·10^–3–9.4·10^–3 mol/dm³, sulfur dioxide (0.3·10^–1–2.0·10^–1 mol/dm³ and Ce(III) (0.2·10^–3–4.8·10^–3 mol/dm³) and dose rate (0.26·10¹⁹–1.0·10¹⁹ eV/dm³·s) on the radiation — chemical yield of oxygen consumption G(–O₂) and accumulation of sulfate G(HSO ₄ ^– ), have been investigated. The reaction proceeds with G(–O₂) reaching 10²–10³ molecule/100eV in a catalytic regime. The reaction rate in perchloric acid medium is 3–4 times lower than that in the sulfuric acid medium and depends on the SO₂, O₂ and Ce(III) concentrations, the reaction order varying from 1.0 to 0 and/or in the reverse direction. The mechanism of the process involves chain propagation with 3 stages and 3 intermediates: SO₃H, HSO₅ and Ce(IV). The catalytic effect is caused by the interaction of HSO₄ with Ce(IV) ions followed by their reduction when interacting with SO₂, yielding SO₃H radicals. Chain termination may be due to one or two of the three intermediates or due to all three particles, the kinetics depending on this. Kinetic equations describing the experimental data have been obtained.     

Analytical application of atomic emission and atomic absorption spectrometry for the determination of imidazoline derivatives based on formation of ion-associates with sodium cobaltinitrite and potassium ferricyanide

Ion-association complexes of Naphazoline HCl (I), Tolazoline HCl (II) and Xylometazoline HCl (III) with [Co(NO₂)₆]^3– and [Fe(CN)₆]^3– were precipitated and the excess of the unreacted iron or cobalt comples was determined. A new method using atomic emission and atomic absorption spectrometry for the determination of the above drags in pure solutions and in pharmaceutical preparations is given. The drugs have been determined in the ranges 0.98–14.76, 0.78–11.80 and 1.12–16.80 g/ml solutions of I, II and III. respectively, using [Co(NO₂)₆]^3–], with mean relative standard deviations of 0.4–1.5% and 1.92%–19.68, 1.52–5.68 and 2.24–22.4 g/ml solutions of I, II and III, respectively using [Fe(CN)₆]^3– with mean relative standard deviations of 0.6–1.6%. The recovery values of 98.12–101.26% indicate high precision and accuracy.     

Titanium(IV) polynuclear hydroxo complexes stabilized in solution by [PW11O39]7? heteropolyanion

[PW₁₁O₃₉]^7– heteropolyanion (HPA) stabilizes Ti(IV) in aqueous solution at Ti:PW₁₁ ratios from 1 to 12 and pH 1–3. Ti(IV) is completely precipitated under these conditions in the absence of HPA. Differential dissolution phase analysis, optical, IR,³¹P and¹⁷O NMR spectra show that one Ti(IV) ion is incorporated into the Keggin lattice. The other ions, most probably, are located on the HPA surface in the form of oligomeric hydroxo fragments: [PW₁₁Ti^IVO₄₀·Ti_n–1 ^IVO_xH_y]^k–. Both types of Ti(IV) ions bind peroxo groups on interaction of the complex with H₂O₂.     

Reactions of chromium(III) complexes with ferricyanide. Magnetism of K2[Cr(salen)(H2O)][Fe(CN)6]·H2O and the crystal structure of [trans-Cr(tn)2Cl2]3[Fe(CN)6]·6H2O [salen2− = N,N′-ethylenebis(salicylideneaminato) dianion,tn = 1,3-diaminopropane]

Two Cr^III–Fe^III complexes, K₂[Cr(salen)(H₂O)][Fe(CN)₆]·H₂O (1) and [trans-Cr(tn)₂Cl₂]₃[Fe(CN)₆]·6H₂O (2), have been prepared. Crystal structure determination shows that complex (2) possesses an ionic salt structure. General physical measurements and magnetic studies indicate that (1) assumes a cyanide-bridged dinuclear structure, and that the Cr^III–Fe^III magnetic coupling through the cyanide bridge is antiferromagnetic, which can be rationalized by the overlap of magnetic orbitals of the same symmetry.