Osmium physical properties

Selected physical properties of rhenium are summarized ia Table 1. The metal is silvery-white and has a metallic luster. It has a high density (21.02 g/cm ). Only platinum, iridium, and osmium have higher densities. The melting poiat of rhenium is higher than that of all other elements except tungsten (mp 3410°C) and carbon (mp 3550°C). 

Ruthenium is a rare, hard, silvery-white metallic element located in group 8, just above osmium and below iron, with which it shares some chemical and physical properties. Both ruthenium and osmium are heavier and harder than pure iron, making them more brittle and difficult to refine. Both ruthenium and osmium are less tractable and malleable... 

Elemental composition Os 74.82%, 0 25.18%. The compound can be identified by its physical properties, such as, odor, color, density, melting-, and boiling points. Its acrid odor is perceptible at concentrations of 0.02 mg/hter in air. The oxide also produces an orange color when a small amount of the compound or its aqueous solution is mixed with an aqueous solution of ammonia in KOH (see Reactions). Aqueous solution of the tetroxide may be analyzed for osmium by AA or ICP spectrometry (see Osmium). Vapors of the tetroxide may be purged from an aqueous solution by helium, adsorbed over a trap, and desorbed thermally by helium onto a GC. Alternatively, a benzene or carbon tetrachloride solution may be injected onto the GC and the compound peak identified by mass spectrometry. The characteristic mass ions for its identification should be 190 and 254. 

Chloroxytrifluoromethane, 26 137-139 reactions, 26 140-143 addition to alkenes, 26 145-146 oxidative addition, 26 141-145 vibrational spectra, 26 139 Chloryl cation, 18 356-359 internal force constants of, 18 359 molecular structure of, 18 358, 359 properties of, 18 357, 358 synthesis of, 18 357, 358 vibrational spectra of, 18 358, 359 Chloryl compounds, reactions of, 5 61 Chloryl fluoride, 18 347-356 chemical properties of, 18 353-356 fluoride complexes of, 5 59 molecular structure of, 18 349-352 physical properties of, 18 352, 353 preparation, 5 55-57 and reactions, 27 176 properties of, 5 48 reactions, 5 58-61, 18 356 synthesis of, 18 347-349 thermal decomposition of, 18 354, 355 vapor pressures, 5 57, 18 353 vibrational spectra of, 18 349-352 Chloryl ion, 9 277 Cholegobin, 46 529 Cholesterol, astatination, 31 7 Cholorofluorphosphine, 13 378-380 h CHjPRj complexes, osmium, 37 274 Chromatium, HiPIP sequence, 38 249 Chromatium vinosum HiPIP, 38 108, 133 Fe4S4 + core, 33 60 Chromato complexes, osmium, 37 287... 

Physical Properties.—Osmium crystallises in cubes or obtuse rhom-bohedra of density ranging from 21-3 to 24.6 It is thus the most dense substance known. It is also very hard (hardness 7-5) and brittle, readily scratching glass, and in the massive form can be heated to the melting-point of zinc (419° C.) without volatilisation.3 At higher temperatures combustion takes place. 

The physical properties, preparation and reactions of ruthenium tetroxide have been reviewed by Lee and van den Engh, Rylander," Haines and Hetuy and Lange. A more vigorous oxidant than osmium tetroxide, its reaction with double bonds produces only cleavage products. " Under neutral conditions aldehydes are formed from unsaturated secondary carbons while carboxylic acids are obtained under alkaline or acidic conditions. For example, Shalon and Elliott" found that ruthenium tetroxide reacted with compound (11) to give the corresponding aldehyde under neutral conditions, but that a carboxylic acid was formed in acidic or alkaline solvents (equation 23). 

The Preparation and Some Physical Properties of Osmium Oxide Pentafluoride, OsOF ... 

The 1 1 chlorine trifluoride-platinum pentafluoride adduct, m. p. I7l , and the 1 1 iodine pentafluoride adduct, m. p. 140° resemble, in their physical properties, the selenium tetrafluoride adducts of osmium pentafluoride (SeF4,OsFg, m. p. 158°) and iridium pentafluoride (SeF. IrFg, m. p. 133°). They are probably bifluorine-bridged monomers ... 

Although a number of complex fluorides of quinquevalent iridium, (e.g. KIrF,) are known, previous attempts to establish the simple fluoride have failed. The absence of a pentafluoride of iridium has become increasingly anomalous as the pentafluorides of the neighbouring elements, rhenium, osmium, and platinum have been prepared. Previous work - indicated that reactions which might have yielded the pentafluoride gave the tetrafluoride instead. The physical properties of this tetrafluoride. (m.p. 106—107 b.p. > 300 ), however, resembled those of a pentafluoride or oxide tetrafluoride. This indicated that iridium tetrafluoride differed structurally from its neighbouring tetrafluorides. 

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Physical properties at 298.15 K (unless otherwise specified) Ruthenium Rhodium Palladium Osmium Iridium Platinum... 

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