Determination of ruthenium and osmium in each other's presence in chloride solutions by direct and third-order derivative spectrophotometry

Ruthenium and osmium (up to 20 mug Ru(Os) ml(-1)) can be determined in chloride solutions directly after absorption of RuO(4) and OsO(4) in hydrochloric acid. In 9 M HCl, RuO(4) and OsO(4) are quantitatively converted into RuCl(6)(2-) (lambda(max) = 480.0 nm, epsilon = 4.8 x 10(3) l mol(-1) cm(-1)) and OsCl(6)(2-) (lambda(max) = 334.8 nm, epsilon = 8.4 x 10(3) l mol(-1) cm(-1)) respectively. Osmium does not interfere with the determination of ruthenium in the form of the RuCl(6)(2-) complex by direct spectrophotometry. The absorbance of the obtained solution at lambda(max) = 480.0 nm corresponds only to the concentration of ruthenium. A derivative spectrophotometric method using numerical calculation of absorption spectra of the RuCl(6)(2-) and OsCl(6)(2-) complexes has been developed for the determination of osmium in a mixture with ruthenium. The interfering effect of ruthenium on the determination of osmium can be eliminated by measuring the value of a third-order derivative spectrum of the OsCl(6)(2-) complex at 350.0 nm ("zero-crossing point" of ruthenium). Simple and rapid determination of ruthenium and osmium in a calibration standard solution of the noble metals (Ru, Rh, Pd, Os, Ir, Pt and Au) for plasma spectroscopy using the proposed methods has been achieved.     

Flotation—spectrophotometric determination of osmium with thiocyanate and methylene blue

A sensitive flotation—spectrophotometric method, based on the ion associate formed by the anionic thiocyanate complex of osmium with the basic dye methylene blue (MB) is described. The ion associate precipitates when the aqueous solution is shaken with toluene, and the separated and washed compound is dissolved in acetone. The molar absorptivity is 2.2 × 10⁵ l mol^-1 cm^-1 at 655 nm. Beer's law is obeyed. The molar ratio of Os:SCN:MB in the separated and washed ion associate is 1:6:3. Ruthenium reacts similarly. The method is applied to the determination of traces of osmium in crucible platinum after separation of osmium by distillation as tetroxide.     

Rapid Spectrophotometric Determination Of Osmium With Cyclohezane 1,3-Dione Bisthiosemicarbazone Monohydrochloride: Simultaneous Determination of Osmium and Platinum

Abstract

A simple, sensitive and rapid spectrophotometric method has been developed for the determination of osmium using cyclohexane 1,3-dione bisthiosemicarbazone mono-hydrochloride (1,3-CHDT.HCl). The method is based on the instantaneous colour reaction between 1,3-CHDT. HCl and osmium(VIII) in sodium acetate—acetic acid buffer medium (pH range 3–6). The osmium complex shows maximum absorbance at 375 nm and considerable absorbance at 510 nm. Although the complex formed between platinum(IV) and reagent (1,3-CHDT.HCl) shows maximum absorbance at 375 nm, it does not show any absorbance at 510 nm. Simultaneous determination of osmium and platinum is carried out when present alone and in presence of other foreign (associated) ions. Some physico-chemical and analytical characteristics of osmium and platinum complex are described. Interference of various foreign ions have studied and osmium is estimated selectively in the presence of constituents of platinum ores.     

Osmium Complexes Useful in the Preparation of Metal Thin Film and Highly Efficient Electroluminescent Devices

Treatment of β-diketone ligand, such as hfacH (hexafluoroacetylacetone), with Os3(CO)12 in a stainless steel autoclave at elevated temperature afforded the corresponding mononuclear osmium complex [Os(CO)3(hfac)(tfa)] (1) in good yield. This complex is highly volatile and displays moderate stability at the higher temperatures; thus, it can be utilized for depositing metal thin-film material with overall quality comparable or better than those deposited using the commercially available chemical reagents. Moreover, combination of Os3(CO)12 with another class of chelate ligand such as 3-trifluoromethyl-5-(2-pyridyl) pyrazole (ppz)H gave formation of the Os(H) dicarbonyl complex [Os(CO)2(ppz)2] (2). This osmium complex shows blue phosphorescence at room temperature, which is characteristic for the 3ππ* emission with vibronic progressions at 430,457 and 480 nm. The remarkable photophysical properties were rationalized by a combination of π electron accepting CO ligand, relative ppz orientation and heavy-atom enhanced spin-orbit coupling effects. Related chemical transformations that afforded other useful luminescent Os complexes are presented.     

Spectrophotometric determination of osmium with 1,5-diphenylcarbazide

The formation of the bluish violet osmium-diphenylcarbazide complex in weakly acidic solution is utilized for the determination of osmium by spectrophotometry. When measurements are made at 560 nm, after extraction of the complex into isobutyl methyl ketone, Beer's law is obeyed up to 150 mug of osmium. Relatively few ions interfere, and these can be masked with EDTA and fluoride.     

Spectrophotometric determination of osmium with p-(morpholino)-n-(4'-hydroxy-3'-methoxy)benzylidineaniline

A sensitive spectrophotometric determination of osmium is based on the blue color (absorption maximum at 615 mμ formed by reaction of osmium with p-(morpholino)-N-(4'-hydroxy-3'-methoxy)benzylidineaniline (“anil”) in acetate-buffered solution containing ethanol to prevent formation of a precipitate, Full color development is attained in I h at room temperature, and the color is stable for several hours. The absorbance is reproducible. The optimum concentration range for I-cm optical path is about I to 4 p.p.m. of osmium. Several transition elements interfere ; osmium can be separated as its tetroxide by the usual distillation method. The blue product is a cationic complex formed by reaction of anil with osmium in a 2 : I mole ratio. When osmium is in excess a red cationic complex (absorption maximum at 466 mμ) is formed by a I : I reaction between osmium and the reagent. The I : I complex is slowly converted to the 2 : I complex by excess reagent.     

The spectrophotometric determination and solvent extrāction of osmium with o-(β-benzoylthiourido)benzoic acid as reagent

o-(β-Benzoylthiourido)benzoic acid is proposed as a spectrophotometric reagent for the determination of osmium. The brownish yellow complex formed is soluble in alcohol and in other organic solvents. The colour system obeys Beer's law from 3 to 18 p.p.m. of osmium at 410 mμ with an optimum range of 3–15 p.p.m., where the percent relative error per 1% absolute photometric error is 2.75%. A 1:1 complex is formed and the dissociation constant is of the order of 10^-5. With prior extraction of palladium as the axide complex with n-butanol, osmium can be separated from almost all ions, including those of platinum metals, by extraction witli ethyl acetate.     

Extraction and direct spectrophotometric determination of ruthenium with ethyl-alpha-isonitrosoacetoacetate

Ruthenium is extracted by benzyl alcohol from 5M LiCl containing ethyl-alpha-isonitrosoacetoacetate at pH 4-6. The extraction is quantitative if the solution is heated to boiling for 15 min. The benzyl alcohol extract shows maximum absorbance at 470 nm and at this wavelength Beer's law is obeyed over the ruthenium concentration range 0.1-1.8 mug ml . The error is 4% for 0.5 mug ml .     

Extractive Separation and Spectrophotometric Determination of Traces of Ruthenium from Mixtures Containing Excess Platinum Group Metals

Abstract

A highly selective, sensitive, and rapid method has been developed for the spectrophotometric determination of ruthenium with 5-chloro-2-hydroxythiobenzhydrazide after extraction into molten naphthalene. Ruthenium was determined in the range 1.2–4.5 ppm. The complex was stable for more than 12 h with molar absorptivity of 1.516 × 10⁴ L mol^?1 cm^?1 and detection limit of 0.0066 ppm. The method was found to be selective for ruthenium in the presence of a large number of diverse ions. Ruthenium was determined in various synthetic mixtures. The method permits the sequential separation and determination of ruthenium, osmium, and platinum from their mixtures.     

Flotation-spectrophotometric determination of osmium (ruthenium) with thiocyanate and Capri blue

A sensitive flotation-spectrophotometric method for the determination of osmium, based on the ion associate formed by the anionic thiocyanate osmium complex with oxazine basic dye, Capri blue (CB), has been developed. The ion associate is separated by shaking the aqueous solution (pH 2–3) with diisopropyl ether, washing the precipitate with water, and dissolving it in methanol. Molar absorptivity in this method amounts to 2.7 × 10⁵ liters mol⁻¹ cm⁻¹ at 630 nm. The molar ratio Os:SCN:CB in the separated associate is 1:8:5. Under the conditions of the determination of osmium, ruthenium can be determined as well. Metals that form anionic thiocyanate complexes, including other platinum metals, interfere. The method becomes highly selective for osmium and ruthenium after their separation by distillation as tetroxides. Osmium and ruthenium were determined with Capri blue after their extractive separation as thiocyanate complexes.     

Spectrophotometric determination of osmium with 2R-acid in the presence of other platinum metals

Osmium(VIII) produces two coloured species with lambda(max) 680 nm (green) and 530 nm (red) with excess of 2-amino-8-naphthol-3,6-disulphonic acid in aqueous solution. The green complex is stable between pH 2.5 and 8.0 and the red complex between pH 11.0 and 12.0. The effects of temperature and time, reagent concentration, optimum conditions for the spectrophotometric determination of trace amounts of osmium, and other variables, have been studied at pH 11.5. At this pH, other platinum metals do not interfere. The sensitivity of the colour reaction is 0.2 microg/cm(2) and the system conforms to Beer's law over a concentration range of 1.5-10 microg of osmium.     

Study of the system Os(IV)-chloride-brilliant green: Extraction-spectrophotometric determination of osmium

A sensitive extraction-spectrophotometric method of the determination of osmium, taking advantage of the ion-associate of the chloride osmium anion with brilliant green has been developed. The complex is extracted from aqueous phase with a mixture of C₆H₅Cl + CCl₄ (3 + 1). Molar absorptivity () at 640 nm is 1.95 × 10⁵ liters mol⁻¹cm⁻¹ (specific ABSORPTIVITY = 1.03). The relative standard deviation is 1–3%. The mole ratio of Os:BG in the complex is 1:3. Platinum metals interfere with the determination of osmium. The determination can be highly selective after preliminary separation of osmium by distillation as OsO₄.     

Rapid and selective determination of osmium(IV) by UV-visible spectrophotometry using o-methylphenyl thiourea as a chromogenic chelating ligand: sequential separation of osmium(IV), rhodium(III) and platinum(IV)

The objective of this research work was to develop a simple, highly sensitive and precise method for spectrophotometric determination of osmium(IV). O-Methylphenyl thiourea (OMPT) coordinates with osmium(IV) as a 1:1 (osmium(IV)–OMPT) complex in hydrochloric acid media (0.8 mol l^?1). The novelty of the investigated method is instant complex formation at room temperature with no need of heating or standing. The complex is stable for more than 8 days. The method is applicable over a wide linearity range (up to 110 µg ml^?1). A low reagent concentration is required (2 ml, 0.009 mol l^?1 in ethanol). The complex exhibits maximum absorption in the range of wavelength 510–522 nm and 514 nm was selected for further study. The molar absorptivity was 1.864 × 10³ l mol^?1 cm^?1, Sandell’s sensitivity was 0.102 µg of osmium(IV) cm^?2. Proposed method was successfully applied for separation and determination of osmium(IV) from binary and ternary synthetic mixtures containing associated metal ions. A scheme for mutual separation of osmium(IV), rhodium(III) and platinum(IV) is developed.     

Novel europium and osmium complexes for pure red light emitting diode applications

Pure and efficient red light-emitting diodes based on novel europium (Eu) and osmium (Os) complexes were demonstrated. The Eu complex, with dendron substituted diketone ligands, exhibits high photoluminescence efficiency of 45%. When a copolymer containing carbazole and 1,3,4-oxadiazole groups was used as the host, narrow electroluminescence at 617 nm was achieved, with a full width at half maximum of 4 nm and a maximum external quantum efficiency (η) of 0.80%. The Os complex shows pure red emission peaking at 650 nm. The Commission Internationale de l'Eclairage (CIE) chromaticity coordinates (x, y) are (0.65, 0.33). Maximum η and brightness achieved were 0.82% and 590 cd/m², respectively.     

Spectrophotometric study of the ruthenium(III,II)–2,2′,2″- terpyridine system

Ruthenium(III) reacts with 2,2′,2″-terpyridine in aqueous solution at pH 3.0–4.5, when heated at 85 °C for 2 min, giving a green cationic complex with an absorbance maximum at 690 nm. The color is stable for at least 25 h. The system conforms to Beer's law. The optimal range for measurement (1.00-cm optical path) is 2–10 p.p.m. Ru; the molar absorptivity is 8.3 ·10³. Ruthenium(II) reacts with terpyridine at pH 5.5 to develop an amber cationic complex (absorption maximum at 475 nm) on heating at 95° C for 45 min. The color is apparently stable indefinitely. The system conforms to Beer's law; the optimal range is 1–5 p.p.m. Ru; the molar absorptivity is 1.45·10⁴ l mol^?1 cm^?1. Common anions do not interfere; separation as RuO₄ is necessary when iron and a few other transition cations are present. The green complex, a strong oxidant, is converted to the ruthenium(II) complex by oxidation of water, slowly at room temperature, or more quickly by longer heating and/or higher temperature, and by increase of pH. The Ru(II) complex can be converted to the Ru(III) complex by strong oxidants such as Ce(IV). In the amber complex, the reaction ratio is 1 Ru: 2 terpyridine, in which the ligand is tridentate, whereas in the green complex the reaction ratio is 1 Ru : 3 terpyridine, the latter acting only as a bidentate ligand. Short gentle warming of a mixture of ruthenium(III) and terpyridine first produces a transient unidentified blue-colored species (absorbance at 790 nm).     

Separation and determination of ruthenium by evolution with chromium(VI)-condensed phosphoric acid reagent

Ruthenium in various chemical forms can be evolved as the tetroxide from insoluble matrix materials by heating the sample with chromium(VI)-condensed phosphoric acid reagent (abbreviated as Cr(VI)-CPA). Because of its excellent decomposing power for various solid samples, condensed phosphoric acid is very useful in the chemical analysis of various insoluble materials, and when an oxidizing agent such as potassium dichromate is added in the CPA medium, drastic oxidation proceeds on heating. This method is now extended to the separation of ruthenium from marine sediments. During the reaction with Cr(VI)-CPA ruthenium tetroxide is evolved and collected in an absorbent solution of 6M hydrochloric acid and ethanol (1:1), and the ruthenium is then determined spectrophotometrically with thiourea or radiometrically by counting the beta or gamma-activity. Osmium, which can be evolved as the tetroxide by the same treatment, can be eliminated beforehand by heating the sample with Ce(IV)-CPA, which removes osmium but not ruthenium. The successive distillations by means of Ce(IV)-CPA and Cr(VI)-CPA give satisfactory results for the separation between osmium and ruthenium. This method might be useful for the separation of ruthenium in geochemical or neutron-activation analysis.     

Ru and Os complexes containing a P,N-donor heterotopic ligand: the effect of solvent on stereochemistry

Ruthenium and osmium complexes of the general formula MCl 2(PyP) 2 (where PyP is the P,N- donor ligand 1-(2-diphenylphosphinoethyl)pyrazole) were synthesized from MCl 2(PPh 3) 3 (where M = Ru or Os). Three of the five possible stereoisomers of RuCl 2(PyP) 2 were synthesized and characterized in solution by multinuclear NMR spectroscopy, and the structure of these in the solid state was determined by X-ray crystallography. Two of the analogous Os isomers were also synthesized. It was found that different solvents induced isomerization between these stereoisomers, indicating either lability of the chloride anion or hemilability of the PyP ligand. Bimetallic complexes of the general formula [Ru(mu-Cl)(PyP) 2] 2[X] 2 were synthesized from chloride abstraction from RuCl 2(PyP) 2 using either silver (X = OSO 2CF 3, BF 4) or sodium (X = BPh 4) salts. The osmium analogue of the Ru bimetallic complexes, [Os(mu-Cl)(PyP) 2] 2[BPh 4] 2, was also synthesized. Solid-state structures were obtained using X-ray crystallography for the osmium bimetallic complex and the ruthenium bimetallic complex where X = OSO 2CF 3. The hemilability of PyP was demonstrated through the synthesis of RuCl 2(CO)(kappa (1)- P-PyP)(kappa (2)- P, N-PyP), which contains one pendant PyP ligand, bound through the P-donor atom.     

Lösungsmittelextraktion der Elemente Ruthenium und Osmium

Zusammenfassung An den beiden Elementen Ruthenium und Osmium wurden Lösungs-mittelextraktionsversuche vorgenommen. Es wurde eine Vorschrift zur Extraktion von Ruthenium(VII) mit Tetraphenylarsoniumchlorid-Chloroform ausgearbeitet. 96 bis 98% des Rutheniums konnten in einem Arbeitsgang extrahiert werden.Für die Extraktion des Osmiums mit dem flüssigen Anionenaustauscher LA-1 wurde eine Vorschrift ausgearbeitet, die einen Verteilungskoeffizienten von 24 ergibt.Durch die beiden angeführten Extraktionsmethoden läßt sich eine Trennung der beiden Elemente Ruthenium und Osmium bequem durchführen.

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Summary Solvent extraction trials were made with both ruthenium and osmium. A procedure was developed for the extraction of ruthenium(VII) with tetraphenylarsonium chlorid-chloroform. It was possible to extract 96 to 98% of the ruthenium in a single operation. A method for extraction of osmium with the liquid anion exchanger LA-1 was worked out. The two elements ruthenium and osmium can be readily separated by means of the two extraction methods.

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Résumé On a entrepris des recherches sur l'extraction par un solvant de deux éléments, le ruthénium et l'osmium. On a mis au point un mode opératoire pour extraire le ruthénium-VII par le système chlorure de tétraphénylarsonium-chloroforme. On peut extraire ainsi 96 à 98% du ruthénium.On a mis au point un mode opératoire pour l'extraction de l'osmium par l'échangeur anionique liquide LA-I, qui donne un coefficient de partage de 24.On peut réaliser commodément une séparation des deux éléments, ruthénium et osmium, au moyen des deux méthodes d'extraction indiquées.

     

The Simultaneous Spectrophotometric Determination of Osmium and Ruthenium

Abstract

A spectrophotometric procedure is described for the simultaneous determination of osmium and ruthenium in the form of bromo complexes. It was found that a blue ruthenium-thiourea complex could be formed in 6.7 M HBr solutions while the osmium could be maintained as the hexabromoosmate complex. Absorption maxima were at 620 μ for the ruthenium complex and at 446 μ for the osmium complex. Molar absorptivities for the ruthenium complex were 2.47 × 10³ at 620 μ and 763 at 446 μ. For the osmium complex molar absorptivities were 328 at 620 μ and 6.81 × 10³ at 446 μ. The method is useable over the range of 5 to 30 ppm with an absolute error of = 1 ppm over the range. Other platinum metals interfere.     

Prochlorperazine bismethanesulfonate: Sensitive and selective reagent for the spectrophotometric determination of microgram amounts of osmium

Prochlorperazine bismethanesulfonate (PCPMS) is proposed as a new sensitive and selective reagent for the spectrophotometric determination of microgram amounts of osmium. PCPMS forms a red-colored species with osmium(VIII) or osmium(VI) instantaneously at room temperature in 5 M phosphoric acid medium. The red species exhibits maximum absorbance at 529 nm. Beer's law is valid over the concentration range 0.05–3.6 ppm for osmium(VIII) and 0.15–6.4 ppm for osmium(VI). Sandell's sensitivity of the reaction is 2.89 nm cm^?2 for osmium(VIII) and 4.24 ng cm^?2 for osmium(VI). The effects of time, temperature, acidity, order of addition of reagents, reagent concentration, and diverse ions are investigated. The application of the proposed method in the determination of osmium content in synthetic ores has been explored.