The determination of traces of osmium in ruthenium sponge by neutron activation analysis

Tracer techniques confirmed that a quantitative separation of osmium and ruthenium is possible by distillation from a hydrogen peroxide-sulphuric acid solution. Osmium distils quantitatively as OsO₄ at a temperature of 105 ± 5° in about 30 min. The ruthenium contamination is approximately 0.01 %.In the present work a neutron activation analysis is described for the determination of traces of osmium in ruthenium sponge. When quantities of osmium below 30 p.p.m. are determined, the ruthenium contamination of the distillate must be taken into account, when the measurement is made with a 3” x 3” NaI(Tl) crystal. This can easily be achieved by measurement in two energy regions with a γ-spectrometer or with a multichannel pulse-height analyzer. With a NaI(T1) wafer as detector, the correction for ruthenium can be omitted for osmium concentrations above 10 p.p.m.With the addition method of analysis, 10–2000 p.p.m. in 10-mg samples of ruthenium sponge can be determined by neutron activation analysis. Chemical separation is necessary but no carriers are required. The lowest limit of determination is about 3 p.p.m. for a 3” x 3” crystal; for the wafer, about 1 p.p.m. can be determined.     

The simultaneous determination of osmium,ruthenium, iridium and gold in platinum by neutron activation analysis

Osmium, ruthenium, iridiuim and gold can be determined simultaneously in 100-mg platinum samples after irradiation for 11 days at a thermal neutron flux of 4'1011 n.cm^-2.sec^-1. An addition method of analysis is used; samples are dissolved in small sealed silica tubes before activation. After irradiation, Os and Ru are distilled from sulfuric acid-sodium bromate, Ru being determined by counting the 498-keV peak of ¹⁰³Ru; Os is determined after a second distillation. Gold is extracted with ethyl acetate from the residue of the first distillation; the ratio ¹⁹⁸Au/¹⁹⁹Au is a direct measure for the gold content, with appropriate correction for the second-order reaction ¹⁹⁶Pt(n,γ)¹⁹⁷Pt→¹⁹⁷Au(n,γ)¹⁹⁸Au. Ir is determined in the residual aqueous phase using the 317-keV peak of ¹⁹²Ir; a correction for the platinum activity (¹⁹¹Pt) is made. The lower limit of determination is ca. 0.5 p.p.m. for ruthenium, ca. 0.2 p.p.m. for osmium, ca. O.1 p.p.m. for gold and ca. O.1 p.p.m. for iridium. After a separation of Pt from Ir, the sensitivity for Ir can easily be improved to < 10 p.p.b.     

Photometric determination of osmium with thiourea after extraction of the tetroxide

A general method for the determination of 5–1000 γ of osmium involves extraction of osmium tetroxide with chloroform or carbon tetrachloride, followed by shaking the organic solvent with a sulfuric acid solution, of thiourea to form red Os(NH₂CSNH₂)₆⁺³, whose color intensity is measured photometrically. A sharp separation of osmium from ruthenium can be obtained by reducing Os(VIII) and Ru(VIII) with ferrous sulfate and then oxidizing Os(IV) to Os(VIII) with nitric acid; ruthenium remains reduced and is not extracted by chloroform or carbon tetrachloride.     

Loss of iridium,osmium and ruthenium from aqueous solutions during storage

Aqueous solutions of iridium are stable (within 3 %) over a four-month storage period in a variety of container types and over a range of acid concentrations. Standard solutions of water-soluble iridium compounds at pH 7 can be employed reliably. Rapid loss of osmium and ruthenium from aqueous solutions at pH 7 means that standard solutions must be used within 1 day of preparation. Nitric acid solutions of osmium and ruthenium should also be avoided. The six plastics studied are unacceptable containers for 0.1 M hydrochloric acid solutions of osmium; 1 M hydrochloric acid is an adequate preservative for osmium solutions for up to two months and for ruthenium solutions for up to four months in glass, quartz or polyethylene containers.     

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.     

Tiron as a spectrophotometric reagent for the estimation of osmium

A method for the spectrophotometric determination of osmium with tiron as a reagent has been described. The reagent forms a soluble and stable coloured complex on heating with osmium in the presence of sodium acetate. The regions of maximum and minimum absorptions are at 470 mμ and 410 mμ, respectively, and the system obeys Beer's law from 2 to 32 p.p.m. of osmium. But the optimum range, with the relative analysis error of 2.878% per 1% absolute photometric error, is from 8 to 24 p.p.m. of osmium. The sensitivity of the reaction is 0.033 μg/cm² (SANDELL) and the molar extinction coefficient is 5706. In solution, the complex is formed when the osmium and the reagent are in a ratio of l : 1 ; it has an instability constant equal to approximately 5.57? 10^-5.     

Spectrophotometric determination of iridium(III) and osmium(VIII) with phenanthrenequinone monoxime after extraction into molten Naphthalene

Summary Conditions have been established for the extraction of iridium (III) and osmium(VIII) as their phenanthrenequinone monoximates into molten naphthalene. The naphthalene is allowed to solidify, separated by filtration, dried with filter paper and dissolved in chloroform. The absorbance is measured at 470 nm for iridium and 475 nm for osmium. Beer's law is obeyed in the concentration ranges 3.2–38.6g of iridium and 1.0–10.9g of osmium in 10 ml of chloroform. The molar absorptivities are 2.3×10⁴ and 8.8×10⁴l. mole^–1.cm^–1 for iridium and osmium respectively. The optimum pH range for the extraction is 4.6–7.4 for iridium and 6.8–10.5 tor osmium. Interferences have been studied in detail and the method successfully applied to various synthetic mixtures. The two metals can be determined sequentially (in the absence of interfering ions), osmium first.

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Spektrophotometrische Bestimmung von Ir(III) und O's(VIII) mit Phenanthrenchinonmonoxim nach Extraktion mit geschmolzenem Naphthalin

Zusammenfassung Die Extraktionsbedingungen für Ir(III) und Os(VIII) als Phenanthrenchinonmonoximate mit geschmolzenem Naphthalin wurden ermittelt. Man läßt das Naphthalin erstarren, filtriert es, trocknet es mit Filterpapier und löst es in Chloroform. Die Absorbanz wird bei 470 nm gemessen für Ir und bei 475 nm für Os. Das Beersche Gesetz gilt für Ir im Konzentrationsbereich 3,2–38,6g und für Os zwischen 1,0 und 10,9g/10 ml Chloroform. Die molare Absorption beträgt 2,3×10⁴ bzw. 8,8×10⁴l·mol^–1·cm^–1 für Ir bzw. Os. Das optimale pH-Gebiet für die Extraktion von Ir liegt bei 4,6–7,4, für Os bei 6,8–10,5. Störungen wurden im Detail untersucht und das Verfahren mit Erfolg für verschiedene Gemische angewendet. In Abwesenheit störender Ionen können Osmium und Iridium hintereinander bestimmt werden.

     

Novel co-catalytic activity of zinc metal with classical initiators for the ring opening polymerisation of norbornene

Zinc metal was shown to considerably increase the activity of the metal(III) chloride salts of ruthenium, iridium and osmium as metathesis initiators for the ROMP of norbornene. The stereochemistry of the polymers formed was determined by ¹H and ¹³C NMR. Formation of the initial carbene species is not via the normally accepted vinyl hydride mechanism. An alternative mechanism involving a metallacyclopentane intermediate is postulated.     

Microwave Irradiation for the Facile Synthesis of Transition‐Metal Nanoparticles (NPs) in Ionic Liquids (ILs) from Metal–Carbonyl Precursors and Ru‐, Rh‐, and Ir‐NP/IL Dispersions as Biphasic Liquid–Liquid Hydrogenation Nanocatalysts for Cyclohexene

Stable chromium, molybdenum, tungsten, manganese, rhenium, ruthenium, osmium, cobalt, rhodium, and iridium metal nanoparticles (M‐NPs) have been reproducibly obtained by facile, rapid (3 min), and energy‐saving 10 W microwave irradiation (MWI) under an argon atmosphere from their metal–carbonyl precursors [M_x(CO)_y] in the ionic liquid (IL) 1‐butyl‐3‐methylimidazolium tetrafluoroborate ([BMIm][BF₄]). This MWI synthesis is compared to UV‐photolytic (1000 W, 15 min) or conventional thermal decomposition (180–250 °C, 6–12 h) of [M_x(CO)_y] in ILs. The MWI‐obtained nanoparticles have a very small (<5 nm) and uniform size and are prepared without any additional stabilizers or capping molecules as long‐term stable M‐NP/IL dispersions (characterization by transmission electron microscopy (TEM), transmission electron diffraction (TED), and dynamic light scattering (DLS)). The ruthenium, rhodium, or iridium nanoparticle/IL dispersions are highly active and easily recyclable catalysts for the biphasic liquid–liquid hydrogenation of cyclohexene to cyclohexane with activities of up to 522 (mol product) (mol Ru)^?1 h^?1 and 884 (mol product) (mol Rh)^?1 h^?1 and give almost quantitative conversion within 2 h at 10 bar H₂ and 90 °C. Catalyst poisoning experiments with CS₂ (0.05 equiv per Ru) suggest a heterogeneous surface catalysis of Ru‐NPs.     

Flotation-spectrophotometric determination of ruthenium in the Ru(IV)-chloride-rhodamine 6G-toluene system

Summary Flotation-Spectrophotometric Determination of Ruthenium in the Ru(lV)-Chloride-Rhodamine 6G-Toluene System The reduction of RuO₄ in hydrochloric acid has been examined. A sensitive flotation-spectrophotometric method of the determination of ruthenium based on the ion associate formed by the anionic chloride complex of ruthenium RuCl₆ ^2– with the basic dye Rhodamine 6G (R6G) has been developed. The solution of the ion associate obeys Beer's law up to the concentration of 0.25g Ru/ml. The ion associate precipitates when the aqueous solution is shaken with toluene. The separated compound is dissolved in acetone. The molar absorptivity () at 530 nm is 5.1×10⁵ 1·mole^–1-cm^–1. The relative standard deviation is 3–7%. The mole ratio of RuR6G in the complex is 15. Osmium reacts similarly. The determination of ruthenium can be selective after the preliminary separation of osmium as OsO₄. The method was applied to the determination of microgram amounts of ruthenium in crucible platinum.     

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.     

Ruthenium and Osmium Podate Cyclodextrins with Dual-function Recognition Sites for Luminescent Sensing

A multifunctionalised podand cyclodextrin ligand, β-CD-(urebpy)⁷, with urea--bipyridine binding sites leads to ruthenium and osmium, {Ru[β-CD-(urebpy)⁷]}[PF⁶]² {Os[β-CD-(urebpy)⁷]}[PF⁶]², cyclodextrins. The bipyridine ligands are preorganised by the cyclodextrin cavity encapsulating the ruthenium and osmium core to give photoactive metallocyclodextrins. The podate cyclodextrin complexes show characteristic ruthenium and osmium tri-bipyridine luminescence. It is demonstrated that the ruthenium cyclodextrins participate in sensing schemes through both the cyclodextrin cavity and the urea cage at the bottom of the cyclodextrin rim. Luminescence quenching of the ruthenium emission is observed by addition of anthraquinone guests in the cyclodextrin cavity or addition of dihydrogen phosphate anion.     

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.     

Dicarba-closo-dodecarborane-containing half-sandwich complexes of ruthenium, osmium, rhodium and iridium: biological relevance and synthetic strategies

This review describes how the incorporation of dicarba-closo-dodecarboranes into half-sandwich complexes of ruthenium, osmium, rhodium and iridium might lead to the development of a new class of compounds with applications in medicine. Such a combination not only has unexplored potential in traditional areas such as Boron Neutron Capture Therapy agents, but also as pharmacophores for the targeting of biologically important proteins and the development of targeted drugs. The synthetic pathways used for the syntheses of dicarba-closo-dodecarboranes-containing half-sandwich complexes of ruthenium, osmium, rhodium and iridium are also reviewed. Complexes with a wide variety of geometries and characteristics can be prepared. Examples of addition reactions on the metal centre, B-H activation, transmetalation reactions and/or direct formation of metal-metal bonds are discussed (103 references).     

Synthesis and cytotoxicity of methyl-substituted 8-quinolineselenolates of ruthenium,rhodium, osmium,and iridium

A series of 2-methyl, 4-methyl, and 2,4-dimethyl-8-quinolineselenolates of ruthenium, rhodium, osmium, and iridium has been synthesized and their cytotoxicity towards HT-1080 (human fibrosarcoma) and MG-22A (mouse hepatoma) tumor cells studied. It was found that all of the osmium complexes had a high cytotoxicity towards both cell lines. Their toxicity towards the normal mouse embryonic fibroblasts NIH-3T3 depends on the position and number of methyl groups in the quinoline ring and decreases in the order 2-Me > 4-Me > 2,4-Me₂. The greatest selectivity in cytoxic activity is noted for iridium 4-methyl-8-quinolineselenolate and ruthenium 2-methyl-8-quinolineselenolate. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 2, pp. 230–236, February, 2009.     

Complexes of Ruthenium and Osmium with 4-Amino-2-Mercapto-5-Nitroso-6-Pyrimidinol

Ruthenium(III) and osmium(VIII) form coloured complexes with 4–amino ?2-mercapto-5-nitroso-6-pyrimidinol (ammonium salt). The complexes have been spectrophotometrically studied and made use of in determination of the two metals; the reaction with ruthenium is particularly sensitive (0.006 μg of ruthenium/cm²for 0.001 absorbance). Many ions do not interfere in the determination.     

Spectrophotometric determination of osmium: Sulphanilic acid as a reagent

Sulphanilic acid has been found to be a very effective reagent for the spectrophotometric determination (if hexavalent and octavalent osmium in the pH range between 1.8 – 3.5. In these two valence states, the element forms a dark-violet complex with the reagent, the absorption maximum of the complex being at 490 mμ. As most of the other ions interfere in the determination, the element must be separated as osmic acid by nitric acid distillation. Beer's law is obeyed in the case of 0.5 to 9 p.p.m. of osmium (VIII) and l to 18 p.p.m. of osmium (VI); tin-optimum concentration ranges are from 2 to 8 p.p.m. for osmium(VIII) and from 4 to 16 p.p.m. for osmium(Vl). In these ranges, the % relative errors per 1% absolute photometric error are 3.02 for osmium (VIII) and 3.1 for osmium(VI). Application of the method of continuous variations and the molar ratio method indicates that in solution hexavalent osmium and the reagent form a 1:2. complex, with an average dissociation constant of 1.2 ? 10^-7.     

Extraction of osmium thiocyanate and its separation from ruthenium by polyurethane foam

A detailed investigation of the conditions for formation and extraction of the thiocyanate complex of osmium by polyether-type polyurethane foam is reported. The complex which formed in solution was extracted through the “cation-chelation” mechanism and distribution coefficients of more than 10⁴ were obtained. By using conditions which inhibit the formation of the osmium-thiocyanate complex, it was possible to leave 95% of osmium in the aqueous phase while extracting more than 95% of ruthenium into polyurethane foam.     

Spectrophotometric determination of osmium : O-Aminophenol-p-sulphonic acid as a reagent

o-Aminophenol-p-sulphonic acid is suggested as a very sensitive reagent for spectrophotometric determination of osmium (VI) and (VIII) at pH 2 5–4. The absorption maximum is at 440 mμ and the optimum concentration range is from 2 to 8 p p m of osmium Moderate amounts of Pd⁺², lr⁺⁴, WO₄^-2, Cr⁺³, Zn⁺², Zr⁺⁴, Mg⁺², Ba⁺² and Sr⁺² do not interfere     

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.