Osmium Oxide Research Articles

Aminodesoxyzucker und glycosylamin-synthesen durch oxyaminierung von hex-2-enopyranosiden und hex-1-enitolen. Synthese des N-acetylmycosamins

The vicinal cis-oxyamination of ethyl 4,6-di- O-acetyl-2,3-dideoxy-α- D- erythro-hex-2-enopyranoside ( 1) and of methyl 4- O-acetyl-2,3,6-trideoxy-α- D- erythro-hex-2-enopyranoside ( 11) as well as of 3,4,6-tri- O-acetyl-1,5-anhydro-2-deoxy- D- arabino-( 17) and - D- lyxo-hex-1-enitol ( 23) with Chloramine T-osmium tetraoxide was investigated (Sharpless reaction). The hex-2-enopyranosides 1 and 11 yielded the corresponding 3-deoxy-3- p-toluenesulfonamido-and 2-deoxy-2- p-toluenesulfonamido-hexopyranosides with the manno configuration in the ratio 2:1. The glycals 17 and 23 reacted with formation of the corresponding α- D- gluco and α- D- galacto N-tosyl-glycosylamines and of the 2-deoxy-2- p-toluenesulfonamidoglycoses in the ratio 3:1. The stereospecifity and the regioselectivity of the reactions are discussed. Quantum chemical calculations on models for the hex-2-enopyranosides 1 and 11 suggest a [3+2] cycloaddition of the N-tosylimido osmium(VIII) oxide in preference to a [2+2] mechanism with participation of the metal species. The preparative importance of the oxyamination reaction is demonstrated by a simple synthesis of N-acetyl-mycosamine.

Solid state preparations and reactions of ternary alkaline-earth osmium oxides

The preparation of CaOsO 3, SrOsO 3, and BaOsO 3 was accomplished by solid state methods at autogenous- and high-pressure. Thermal studies of these derivatives were conducted under argon, and their reactions with air or oxygen at elevated temperature were investigated. The crystallographic properties of all the stoichiometric products were determined from powder diffraction studies and, in certain cases, single crystal investigations. The physical properties of several decomposition products were determined and are reported. Infrared data were obtained for most of the new derivatives.

The effect of digitonin-containing fixatives on the retention of free cholesterol and cholesterol esters.

The influence of several fixation and dehydration procedures on the retention of free cholesterol and cholesterol esters was studied in filter paper preparations. The retention of free cholesterol by the filter paper proved to be decreased by the addition of digitonin to the aldehyde fixative (aqueous phase) and was only slightly enhanced by partial dehydration (alcoholic phase, up to 70% ethanol). Furthermore, digitonin or the presumably formed cholesterol-digitonide complex bound hardly any osmium oxides in glass-fibre paper. Up to 26% of the cholesterol esters was mobilized during the aqueous phase when digitonin was added to the aldehyde fixative. When the glass-fibre papers containing the digitonin cholesterol-ester-osmate complexes were stored in distilled water after fixation, the fluid became turbid. Particulate material isolated from this turbid solution showed ultrastructurally a close resemblance to the 'whorls' observed by several authors in tissue fixed by a digitonin-containing aldehyde fixative. Digitonin also changed the ultrastructural appearance of liposomes, containing lecithin: cholesterol: phosphatidic acid; in a molar ratio 7:2:1. Our observations lead to the conclusion that the use of digitonin-containing fixatives should be abandoned, because they give results which cannot be interpreted. By the use of K4 [Fe(CN)6] containing OSO4 in the post-fixation step were able to demonstrate an increase in the visualization of membranous structures (liposomes).

A new procedure for the recovery of ruthenium and osmium after lead collection

A new scheme is proposed for the quantitative recovery of ruthenium and osmium collected in lead. The lead button is parted with perchloric acid in the presence of a little acetic acid, after heating at 160—180°C. Ruthenium remains totally undissolved;some osmium remains insoluble but some volatilizes and is collected in an alkaline solution. Platinum, palladium and rhodium are completely dissolved in the lead perchloric acid solution, and are removed by simple filtration. After fusion of the residue with sodium peroxide, the solution is combined with the alkaline osmium solution, and ruthenium and osmium oxides are distilled from a bromate—sulphuric acid medium, prior to their spectrophotometric determination. The method provides satisfactory recoveries, with relative standard deviations of 1.45% (Ru) and 6 3% (Os).

The chemical nature of osmium tetroxide fixation and staining of membranes by X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy was used to determine the oxidation states of osmium compounds present in erythrocyte ghost preparations and related systems treated with osmium tetroxide. Osmium tetroxide and cholesterol, codeposited at −100 ° C, began to react at −70 ° C, and Os(VI) was formed. Similarly, Os(VI) was detected for the known cholesterol-osmate ester prepared and purified chemically. However, osmium tetroxide applied in phosphate buffer (pH 7.2) gave rise to large proportions of Os(IV) and Os(III) species in addition to Os(VI) compounds. Egg phosphatidylcholine likewise produced a mixture of Os(VI), Os(IV), and Os(III), but dipalmitoyl phosphatidylcholine failed to give significant amounts of osmium containing products under identical conditions. Glutaraldehyde gave a mixture of compounds with the same osmium oxidation states when allowed to react with aqueous osmium tetroxide. Unfixed and glutaraldehyde-fixed erythrocyte ghosts also produced mixtures of Os(VI), Os(IV) and Os(III) under conditions identical to those of normal tissue processing. Additionally, the mixture of adducts initially formed by treatment with osmium tetroxide was further reduced by dehydration of the tissue with ethanol, resulting in a final mixture which was 50–60% Os(III). The results support a scheme for the reaction of osmium tetroxide with tissues in which the initial reaction site is the double bonds of unsaturated lipids to form Os(VI) derivatives. Subsequent hydrolysis and further reduction yield complexes of Os(IV) and Os(III). A mixture of these three states is present in membrane specimens during microscopic observation. Os(VI) and Os(IV) could be present as osmate esters and osmium dioxide, respectively; Os(III) could be present as an oxo- or amino complex(es). The photoelectron spectrum of intact erythrocyte ghosts can be synthesized from the spectra of phospholipid and cholesterol only, suggesting the predominance of the reaction with lipids in the fixation process.

Neutron activation analysis for osmium and ruthenium in platinum

A sensitive procedure for the simultaneous determination of trace levels of osmium and ruthenium in platinum, by thermal neutron activation analysis utilizing γ-ray spectrometry, was developed. The radiochemical separation method utilized perchloric acid for a selective oxidation of osmium and ruthenium to the volatile tetroxides. The distillation of the tetroxides greatly reduced the radiation hazard presented by the bulk of the activities in the matrix. Activities of 15-day191Os and 40-day104Ru were measured by accumulation of pulses from a 3″ diameter NaI(Tl) crystal detector. Analyses of γ-ray spectra were achieved using digital computer techniques. The procedure provided analyses for a high purity platinum stock of 0.032±0.007 ppm Os and 0.044±0.005 ppm Ru.

Synthesis, mass spectrometric identification, and crystallography of osmium oxide tetrafluoride

Osmium oxide tetrafluoride OsOF4 has been prepared in good yield by the reduction of OsOF5 on a hot tungsten filament and has been characterized by chemical analysis, molecular beam mass spectroscopy, and X-ray crystallography.

The infrared spectra of rhenium and osmium oxide tetrachlorides in the gas phase, condensed phase, and in solution

The infrared spectra of ReOCl4 and OsOCl4 have been measured in the gas phase, in the condensed phase, and in a variety of solvents. In the gas phase spectra the absorption band envelopes corresponding to the metal-oxygen stretching vibrations have been observed and the data are discussed in terms of possible square pyramidal or trigonal bipyramidal structures for the molecules. Evidence is presented showing that acetone and diethyl ether molecules will readily coordinate to these oxide tetrachlorides when dissolved in inert solvents. The effect of traces of water on the same solutions is also described and discussed. Both ReOCl4 and OsOCl4 react with the solvent if dissolved in acetone or diethyl ether and the possibility of the formation of the unknown oxide trichlorides is discussed.

Kinetics on Oxidation Reactions of Fulvenes with Osmium (VIII) Oxide

フルベン類の酸化オスミウム(VIII)による酸化反応の反応速度を,フルベン類の分子軌道法による局在化エネルギーを反応性の指標として用い,さらにEyringの絶対反応速度諭を適用して得た理論値と比較した。この場合,フルベン類と酸化オスミウム(VIII)との二分子反応における反応速度はビリジンを含むクロロホルムを溶媒として用い,25°Cで光学的方法により測定した。 HMOでS=Oを用いて計算した理諭的相対速度はほぼ実験相対速度と一致する。さらに, Suttonの方法による分子軌道計算を用いた結果は実験といっそうよく一致することが明らかとなった。

The preparation and some physical properties of osmium oxide pentafluoride, OsOF5

The emerald green solid, OsOF5, m. p. 59·2, b. p. 100·6°, is the major product of the fluorination of osmium dioxide. Vapour pressure–temperature relationships for the compound are: 32–59°(solid), log Pmm=–2266//T+ 9·064; 59–105°(liquid), log Pmm=–1911//T+ 7·994. The solid is dimorphic being orthorhombic below the transition point of 32·5° and body centred cubic, a= 6·14 A, above it. It is paramagnetic and the susceptibility obeys the Curie-Weiss law approximately, with θ=+6°, the temperature independent magnetic moment being, µ= 1·47 B.M. The infrared spectrum of OsOF5(gas) is similar to that of ReOF5(gas) and is consistent with C4v molecular symmetry.

The structure of the orthorhombic phase of osmium oxide pentafluoride, OsOF5

Crystals of osmium oxide pentafluoride, OsOF5, the first heptavalent osmium compound prepared, are orthorhombic below 32·5°, with four molecules in a unit cell of dimensions a= 9·540, b= 8·669, c= 5·019 A, space group Pnma. The structure was determined from the isostructural relationship with the actinide hexafluorides, and refined by three-dimensional Fourier and difference syntheses.The OsOF5 units of the molecular lattice are distorted from octahedral ligancy. The nature of the distortion is consistent with the greater effective size of the oxygen ligand compared with the fluorine ligands and is indicative of an ordered structure. The chemically significant interatomic distances are: Os–O 1·74 ± 0·03, the trans-Os–F 1·72 ± 0·03, two equatorial Os–F 1·76 ± 0·03, two equatorial Os–F 1·80 ± 0·03 A.

The trinuclear osmium complex, Os 3N 7O 9H 21

The initial product of the interaction of osmium (VIII) oxide and ammonia, OsO 4·NH 3, is shown to undergo dehydration to nitrido-osmic-(VIII) acid which in turn is converted to the trinuclear species Os 3N 7O 9H 21 or its partially dehydrated analogue, Os 3N 7O 7H 17. Infra-red spectral, thermogravimetric analysis, and other data are used to elucidate the structure of Os 3N 7O 9H 21, including its conversion to a related complex Os 3N 5O 5H 7 by dehydration and deammoniation.

THE USE OF THE PHOSPHOTUNGSTIC ACID (PTA) AS A STAIN FOR THE PLASMA MEMBRANE

Many investigations on the structure of cell membranes have been carried out on OsO4 or KMnO4 fixed material; however, these procedures fail to demonstrate any basic difference between the various membranes forming the outer coat of the cytoplasm, the endoplasmic reticulum, the nuclear envelope, and the mitochondria. Thus, Robertson (1959) introduced the concept of the unit membrane, 75 Å thick; however, Finean (1961) found that in some specialized cell surfaces the unit membrane is thicker (100–120 Å).The bleaching procedure with strong oxidants solubilizes and removes from the sections the lower osmium oxides (Merriam, 1958) and makes it possible to evaluate a specific stainability, which otherwise would be masked by the overall staining.Marinozzi and Gautier (1961) introduced the use of phosphotungstic acid (PTA) after the bleaching procedure, and noted that the plasma membrane and some pinocytotic vesicles could be preferentially stained. More recently Latta (1962) obtained similar results, staining with PTA sections of tissues embedded in Epon.The present paper deals with the properties and the nature of the PTA staining.

THE COMPARATIVE ROLES OF OXYGEN AND INHIBITORS IN THE PASSIVATION OF IRON. IV. OSMIUM(VIII) OXIDE

Cathodic polarization of iron electrodes after passivation in osmium(VIII) oxide was used as a means of determining the relative contributions of oxygen and the passivating inhibitor to the total cathodic process. It was found that the rate of reduction of osmium(VIII) oxide greatly exceeds that of oxygen. The reduction product, Os(OH)4, was shown to accelerate the reduction processes, as was found previously with reduction of the pertechnetate ion. A possible mechanism for this action is suggested. The results of the four papers in the series are summarized and discussed in their relation to theories of passivation.

The Passivation of Iron by Osmium(VIII) Oxide and the Origin of the Flade Potential

The Passivation of Iron by Osmium(VIII) Oxide and the Origin of the Flade Potential

The properties and effects of osmium tetroxide as a tissue fixative with special reference to its use for electron microscopy

Osmium tetroxide has been demonstrated to produce excellent fixation of the cytoplasm of cells, particularly for those to be examined in the electron microscope. The action of osmium tetroxide on various tissue constituents differs in its rate and nature. The reaction with lipids is probably by way of an affinity of osmium tetroxide for double bond configurations, thus forming unstable osmium esters which decompose to deposit osmium oxides or hydroxides at the site of activity. Little is known of the reaction of osmium tetroxide with proteins, but in preliminary studies it has been shown to produce quickly an initial gelation of protein solutions which, in the case of albumin, show no well-defined structure in the electron microscope. Coagulation images are, however, evident after other fixing agents. It is postulated that by virtue of its tetrahedral configuration, OsO 4 may form polymer-like structures with proteins establishing linkages at double bond containing groups. This initial gelation may then be followed by a further oxidation and the production of soluble end products, which after long fixation wash out of the cell.