Osmium tetroxide: Difference between revisions

Osmium tetroxide
Stick model osmium tetroxide	Ball and stick model of osmium tetroxide
Names
	Preferred IUPAC name Osmium tetraoxide
	Systematic IUPAC name Tetraoxoosmium
	Other names Osmium(VIII) oxide
Identifiers
CAS Number	20816-12-0 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:88215 ;
ChemSpider	28158 ;
ECHA InfoCard	100.040.038
EC Number	244-058-7;
MeSH	Osmium+tetroxide
PubChem CID	30318;
RTECS number	RN1140000;
UNII	P40W033BGM ;
UN number	UN 2471
CompTox Dashboard (EPA)	DTXSID5042245 ;
	InChI InChI=1S/4O.Os Key: VUVGYHUDAICLFK-UHFFFAOYSA-N ; InChI=1S/4O.Os Key: VUVGYHUDAICLFK-UHFFFAOYSA-N; InChI=1/4O.Os/rO4Os/c1-5(2,3)4 Key: VUVGYHUDAICLFK-TYHKRQCIAE;
	SMILES O=[Os](=O)(=O)=O;
Properties
Chemical formula	OsO4
Molar mass	254.23 g/mol
Appearance	White volatile solid
Odor	Acrid, chlorine-like
Density	4.9 g/cm3
Melting point	40.25 °C (104.45 °F; 313.40 K)
Boiling point	129.7 °C (265.5 °F; 402.8 K)
Solubility in water	5.70 g/100 mL (10 °C) ; 6.23 g/100 mL (25 °C)
Solubility	Soluble in most organic solvents, ammonium hydroxide, phosphorus oxychloride
Solubility in CCl4	375 g/100 mL
Vapor pressure	7 mmHg (20 °C)
Structure
Crystal structure	Monoclinic, mS20
Space group	C2/c
Lattice constant	a = 9.379 Å, b = 4.515 Å, c = 8.630 Å α = 90°, β = 116.58°, γ = 90°
Lattice volume (V)	326.8 Å3
Formula units (Z)	4
Molecular shape	tetrahedral
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H300, H310, H314, H330
Precautionary statements	P260, P262, P264, P270, P271, P280, P284, P301+P310, P301+P330+P331, P302+P350, P303+P361+P353, P304+P340, P305+P351+P338, P310, P320, P321, P322, P330, P361, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)	3 0 1 OX
	Lethal dose or concentration (LD, LC):
LCLo (lowest published)	1316 mg/m3 (rabbit, 30 min); 423 mg/m3 (rat, 4 hr); 423 mg/m3 (mouse, 4 hr)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 0.002 mg/m3
REL (Recommended)	TWA 0.002 mg/m3 (0.0002 ppm) ST 0.006 mg/m3 (0.0006 ppm)
IDLH (Immediate danger)	1 mg/m3
Safety data sheet (SDS)	ICSC 0528
Related compounds
Other cations	Ruthenium tetroxide; Hassium tetroxide
Related osmium oxides	Osmium(IV) oxide
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

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Osmium tetroxide (also osmium(VIII) oxide) is the chemical compound with the formula OsO₄. The compound is noteworthy for its many uses, despite its toxicity and the rarity of osmium. It also has a number of unusual properties, one being that the solid is volatile. The compound is colourless, but most samples appear yellow.^[6] This is most likely due to the presence of the impurity OsO₂, which is yellow-brown in colour.^[7] In biology, its property of binding to lipids has made it a widely-used stain in electron microscopy.

Physical properties

Osmium(VIII) oxide forms monoclinic crystals.^[4]^[8] It has a characteristic acrid chlorine-like odor. The element name osmium is derived from osme, Greek for odor. OsO₄ is volatile: it sublimes at room temperature. It is soluble in a wide range of organic solvents. It is moderately soluble in water, with which it reacts reversibly to form osmic acid (see below).^[9] Pure osmium(VIII) oxide is probably colourless;^[10] it has been suggested that its yellow hue is attributable due to osmium dioxide (OsO₂) impurities.^[11] The osmium tetroxide molecule is tetrahedral and therefore nonpolar. This nonpolarity helps OsO₄ penetrate charged cell membranes.

Structure and electron configuration

The osmium of OsO₄ has an oxidation number of VIII; however, the metal does not possess a corresponding 8+ charge as the bonding in the compound is largely covalent in character (the ionization energy required to produce a formal 8+ charge also far exceeds the energies available in normal chemical reactions). The osmium atom exhibits double bonds to the four oxide ligands, resulting in a 16 electron complex. OsO₄ is isoelectronic with permanganate and chromate ions.

Synthesis

OsO₄ is formed slowly when osmium powder reacts with O₂ at ambient temperature. Reaction of bulk solid requires heating to 400 °C.^[12]

{\ce {Os + 2O2 ->[\Delta T] OsO4}}

Reactions

Oxidation of alkenes

Alkenes add to OsO₄ to give diolate species that hydrolyze to cis-diols. The net process is called dihydroxylation. This proceeds via a [3 + 2] cycloaddition reaction between the OsO₄ and alkene to form an intermediate osmate ester that rapidly hydrolyses to yield the vicinal diol. As the oxygen atoms are added in a concerted step, the resulting stereochemistry is cis.

OsO₄ is expensive and highly toxic, making it an unappealing reagent to use in stoichiometric amounts. However, its reactions are made catalytic by adding reoxidants to reoxidise the Os(VI) by-product back to Os(VIII). Typical reagents include H₂O₂ (Milas hydroxylation), N-methylmorpholine N-oxide (Upjohn dihydroxylation) and K₃Fe(CN)₆/water. These reoxidants do not react with the alkenes on their own. Other osmium compounds can be used as catalysts, including osmate(VI) salts ([OsO₂(OH)₄)]²⁻, and osmium trichloride hydrate (OsCl₃·xH₂O). These species oxidise to osmium(VIII) in the presence of such oxidants.^[13]

Lewis bases such as tertiary amines and pyridines increase the rate of dihydroxylation. This "ligand-acceleration" arises via the formation of adduct OsO₄L, which adds more rapidly to the alkene. If the amine is chiral, then the dihydroxylation can proceed with enantioselectivity (see Sharpless asymmetric dihydroxylation).^[14] OsO₄ does not react with most carbohydrates.^[15]

The process can be extended to give two aldehydes in the Lemieux–Johnson oxidation, which uses periodate to achieve diol cleavage and to regenerate the catalytic loading of OsO₄. This process is equivalent to that of ozonolysis.

Coordination chemistry

OsO₄ is a Lewis acid and a mild oxidant. It reacts with alkaline aqueous solution to give the perosmate anion OsO
₄(OH)²⁻
₂.^[17] This species is easily reduced to osmate anion, OsO
₂(OH)²⁻
₄.

When the Lewis base is an amine, adducts are also formed. Thus OsO₄ can be stored in the form of osmeth, in which OsO₄ is complexed with hexamine. Osmeth can be dissolved in tetrahydrofuran (THF) and diluted in an aqueous buffer solution to make a dilute (0.25%) working solution of OsO₄.^[18]

With tert-BuNH₂, the imido derivative is produced:

OsO₄ + Me₃CNH₂ → OsO₃(NCMe₃) + H₂O

Similarly, with NH₃ one obtains the nitrido complex:

OsO₄ + NH₃ + KOH → K[Os(N)O₃] + 2 H₂O

The [Os(N)O₃]⁻ anion is isoelectronic and isostructural with OsO₄.

OsO₄ is very soluble in tert-butyl alcohol. In solution, it is readily reduced by hydrogen to osmium metal. The suspended osmium metal can be used to catalytically hydrogenate a wide variety of organic chemicals containing double or triple bonds.

OsO₄ + 4 H₂ → Os + 4 H₂O

OsO₄ undergoes "reductive carbonylation" with carbon monoxide in methanol at 400 K and 200 sbar to produce the triangular cluster Os₃(CO)₁₂:

3 OsO₄ + 24 CO → Os₃(CO)₁₂ + 12 CO₂^[12]

Oxofluorides

Osmium forms several oxofluorides, all of which are very sensitive to moisture. Purple cis-OsO₂F₄ forms at 77 K in an anhydrous HF solution:^[19]

OsO₄ + 2 KrF₂ → cis-OsO₂F₄ + 2 Kr + O₂

OsO₄ also reacts with F₂ to form yellow OsO₃F₂:^[20]

2 OsO₄ + 2 F₂ → 2 OsO₃F₂ + O₂

OsO₄ reacts with one equivalent of [Me₄N]F at 298 K and 2 equivalents at 253 K:^[12]

OsO₄ + [Me₄N]F → [Me₄N][OsO₄F]

OsO₄ + 2 [Me₄N]F → [Me₄N]₂[cis-OsO₄F₂]

Uses

Organic synthesis

In organic synthesis OsO₄ is widely used to oxidize alkenes to the vicinal diols, adding two hydroxyl groups at the same side (syn addition). See reaction and mechanism above. This reaction has been made both catalytic (Upjohn dihydroxylation) and asymmetric (Sharpless asymmetric dihydroxylation).

Osmium(VIII) oxide is also used in catalytic amounts in the Sharpless oxyamination to give vicinal amino-alcohols.

In combination with sodium periodate, OsO₄ is used for the oxidative cleavage of alkenes (Lemieux-Johnson oxidation) when the periodate serves both to cleave the diol formed by dihydroxylation, and to reoxidize the OsO₃ back to OsO₄. The net transformation is identical to that produced by ozonolysis. Below an example from the total synthesis of Isosteviol.^[21]

Biological staining

OsO₄ is a widely used staining agent used in transmission electron microscopy (TEM) to provide contrast to the image.^[22] This staining method may also be known in the literature as the OTO^[23]^[24] (osmium-thiocarbohydrazide-osmium) method, or osmium impregnation^[25] technique or simply as osmium staining. As a lipid stain, it is also useful in scanning electron microscopy (SEM) as an alternative to sputter coating. It embeds a heavy metal directly into cell membranes, creating a high electron scattering rate without the need for coating the membrane with a layer of metal, which can obscure details of the cell membrane. In the staining of the plasma membrane, osmium(VIII) oxide binds phospholipid head regions, thus creating contrast with the neighbouring protoplasm (cytoplasm). Additionally, osmium(VIII) oxide is also used for fixing biological samples in conjunction with HgCl₂. Its rapid killing abilities are used to quickly kill live specimens such as protozoa. OsO₄ stabilizes many proteins by transforming them into gels without destroying structural features. Tissue proteins that are stabilized by OsO₄ are not coagulated by alcohols during dehydration.^[15] Osmium(VIII) oxide is also used as a stain for lipids in optical microscopy.^[26] OsO₄ also stains the human cornea (see safety considerations).

Polymer staining

It is also used to stain copolymers preferentially, the best known example being block copolymers where one phase can be stained so as to show the microstructure of the material. For example, styrene-butadiene block copolymers have a central polybutadiene chain with polystyrene end caps. When treated with OsO₄, the butadiene matrix reacts preferentially and so absorbs the oxide. The presence of a heavy metal is sufficient to block the electron beam, so the polystyrene domains are seen clearly in thin films in TEM.

Osmium ore refining

OsO₄ is an intermediate in the extraction of osmium from its ores. Osmium-containing residues are treated with sodium peroxide (Na₂O₂) forming Na₂[OsO₄(OH)₂], which is soluble. When exposed to chlorine, this salt gives OsO₄. In the final stages of refining, crude OsO₄ is dissolved in alcoholic NaOH forming Na₂[OsO₂(OH)₄], which, when treated with NH₄Cl, to give (NH₄)₄[OsO₂Cl₂]. This salt is reduced under hydrogen to give osmium.^[9]

Buckminsterfullerene adduct

OsO₄ allowed for the confirmation of the soccer ball model of buckminsterfullerene, a 60-atom carbon allotrope. The adduct, formed from a derivative of OsO₄, was C₆₀(OsO₄)(4-tert-butyl pyridine)₂. The adduct broke the fullerene's symmetry, allowing for crystallization and confirmation of the structure of C₆₀ by X-ray crystallography.^[27]

Medicine

The only known clinical use of osmium tetroxide is for the treatment of arthritis.^[28] The lack of reports of long-term side effects from the local administration of osmium tetroxide (OsO₄) suggest that osmium itself can be biocompatible, though this depends on the osmium compound administered.

Safety considerations

OsO₄ will irreversibly stain the human cornea, which can lead to blindness. The permissible exposure limit for osmium(VIII) oxide (8 hour time-weighted average) is 2 μg/m³.^[8] Osmium(VIII) oxide can penetrate plastics and food packaging, and therefore must be stored in glass under refrigeration.^[15]

References

^ "Osmium tetroxide ICSC: 0528". InChem.
^ Koda, Yoshio (1986). "Boiling Points and Ideal Solutions of Ruthenium and Osmium Tetraoxides". Journal of the Chemical Society, Chemical Communications. 1986 (17): 1347–1348. doi:10.1039/C39860001347.
^ ^a ^b ^c ^d NIOSH Pocket Guide to Chemical Hazards. "#0473". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b ^c Krebs, B.; Hasse, K. D. (1976). "Refinements of the Crystal Structures of KTcO₄, KReO₄ and OsO₄. The Bond Lengths in Tetrahedral Oxo-Anions and Oxides of d⁰ Transition Metals". Acta Crystallographica B. 32 (5): 1334–1337. Bibcode:1976AcCrB..32.1334K. doi:10.1107/S056774087600530X.
^ "Osmium tetroxide (as Os)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ Girolami, Gregory (2012). "Osmium weighs". Nature Chemistry. 4 (11): 954. Bibcode:2012NatCh...4..954G. doi:10.1038/nchem.1479. PMID 23089872.
^ Cotton and Wilkinson, Advanced Inorganic Chemistry, p.1002
^ ^a ^b "Osmium tetroxide (as Os)". Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHs). Centers for Disease Control. 2 November 2018.
^ ^a ^b Thompson, M. "Osmium tetroxide (OsO₄)". Bristol University. Retrieved 2012-04-07.
^ Butler, I. S.; Harrod, J. F. (1989). Inorganic Chemistry: Principles and Applications. Benjamin / Cummings. p. 343. ISBN 978-0-8053-0247-9. Retrieved 2012-04-07.
^ Cotton, F. A. (2007). Advanced Inorganic Chemistry (6th ed.). New Delhi, India: J. Wiley. p. 1002. ISBN 978-81-265-1338-3.
^ ^a ^b ^c Housecroft, C. E.; Sharpe, A. G. (2004). Inorganic Chemistry (2nd ed.). Prentice Hall. pp. 671–673, 710. ISBN 978-0-13-039913-7.
^ Ogino, Y.; Chen, H.; Kwong, H.-L.; Sharpless, K. B. (1991). "On the timing of hydrolysis / reoxidation in the osmium-catalyzed asymmetric dihydroxylation of olefins using potassium ferricyanide as the reoxidant". Tetrahedron Letters. 32 (32): 3965–3968. doi:10.1016/0040-4039(91)80601-2.
^ Berrisford, D. J.; Bolm, C.; Sharpless, K. B. (1995). "Ligand-Accelerated Catalysis". Angewandte Chemie International Edition. 34 (10): 1059–1070. doi:10.1002/anie.199510591.
^ ^a ^b ^c Hayat, M. A. (2000). Principles and Techniques of Electron Microscopy: Biological Applications. Cambridge University Press. pp. 45–61. ISBN 0-521-63287-0.
^ Brian S. McGilligan; John Arnold; Geoffrey Wilkinson; Bilquis Hussain-Bates; Michael B. Hursthouse (1990). "Reactions of Dimesityldioxo-Osmium(VI) with Donor Ligands; Reactions of MO₂(2,4,6-Me₃C₆H₂)₂, M = Os or Re, with Nitrogen Oxides. X-Ray Crystal Structures of [2,4,6-Me₃C₆H₂N₂]⁺[OsO₂(ONO₂)₂(2,4,6-Me₃C₆H₂)]^–, OsO(NBu^t)(2,4,6-Me₃C₆H₂)₂, OsO₃(NBu^t), and ReO₃[N(2,4,6-Me₃C₆H₂)₂]". J. Chem. Soc., Dalton Trans. (8): 2465–2475. doi:10.1039/DT9900002465.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
^ Kiernan, J. A. "Re: "Disposal" of Osmium Tetroxide "Waste"". Department of Anatomy & Cell Biology, The University of Western Ontario.
^ Christe, K. O.; Dixon, D. A.; Mack, H. G.; Oberhammer, H.; Pagelot, A.; Sanders, J. C. P.; Schrobilgen, G. J. (1993). "Osmium tetrafluoride dioxide, cis-OsO₂F₄". Journal of the American Chemical Society. 115 (24): 11279–11284. doi:10.1021/ja00077a029.
^ Cotton, S. A. (1997). Chemistry of Precious Metals. London: Chapman and Hall. ISBN 0-7514-0413-6.
^ Snider, B. B.; Kiselgof, J. Y.; Foxman, B. M. (1998). "Total Syntheses of (±)-Isosteviol and (±)-Beyer-15-ene-3β,19-diol by Manganese(III)-Based Oxidative Quadruple Free-Radical Cyclization". Journal of Organic Chemistry. 63 (22): 7945–7952. doi:10.1021/jo981238x.
^ Bozzola, J. J.; Russell, L. D. (1999). "Specimen Preparation for Transmission Electron Microscopy". Electron Microscopy: Principles and Techniques for Biologists. Sudbury, MA: Jones and Bartlett. pp. 21–31. ISBN 978-0-7637-0192-5.
^ Seligman, Arnold M.; Wasserkrug, Hannah L.; Hanker, Jacob S. (1966-08-01). "A new staining method (OTO) for enhancing contrast of lipid--containing membranes and droplets in osmium tetroxide--fixed tissue with osmiophilic thiocarbohydrazide(TCH)". The Journal of Cell Biology. 30 (2): 424–432. doi:10.1083/jcb.30.2.424. ISSN 0021-9525. PMC 2106998. PMID 4165523.
^ Unger, Ann-Katrin; Neujahr, Ralph; Hawes, Chris; Hummel, Eric (2020), Wacker, Irene; Hummel, Eric; Burgold, Steffen; Schröder, Rasmus (eds.), "Improving Serial Block Face SEM by Focal Charge Compensation", Volume Microscopy : Multiscale Imaging with Photons, Electrons, and Ions, Neuromethods, vol. 155, New York, NY: Springer US, pp. 165–178, doi:10.1007/978-1-0716-0691-9_9, ISBN 978-1-0716-0691-9, S2CID 226563386
^ Tapia, Juan C.; Kasthuri, Narayanan; Hayworth, Kenneth; Schalek, Richard; Lichtman, Jeff W.; Smith, Stephen J; Buchanan, JoAnn (2012-01-12). "High contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy". Nature Protocols. 7 (2): 193–206. doi:10.1038/nprot.2011.439. ISSN 1754-2189. PMC 3701260. PMID 22240582.
^ Di Scipio, F.; Raimondo, S.; Tos, P.; Geuna, S. (2008). "A simple protocol for paraffin-embedded myelin sheath staining with osmium(VIII) oxide for light microscope observation". Microscopy Research and Technique. 71 (7): 497–502. doi:10.1002/jemt.20577. PMID 18320578. S2CID 9404999.
^ Hawkins, J. M.; Meyer, A.; Lewis, T. A.; Loren, S.; Hollander, F. J. (1991). "Crystal Structure of Osmylated C₆₀: Confirmation of the Soccer Ball Framework". Science. 252 (5003): 312–313. Bibcode:1991Sci...252..312H. doi:10.1126/science.252.5003.312. PMID 17769278. S2CID 36255748.
^ Sheppeard, H.; D. J. Ward (1980). "Intra-articular osmic acid in rheumatoid arthritis: five years' experience". Rheumatology. 19 (1): 25–29. doi:10.1093/rheumatology/19.1.25. PMID 7361025.

External links

[1] "Osmium tetroxide ICSC: 0528". InChem.

[2] Koda, Yoshio (1986). "Boiling Points and Ideal Solutions of Ruthenium and Osmium Tetraoxides". Journal of the Chemical Society, Chemical Communications. 1986 (17): 1347–1348. doi:10.1039/C39860001347.

[PGCH-3] NIOSH Pocket Guide to Chemical Hazards. "#0473". National Institute for Occupational Safety and Health (NIOSH).

[s1-4] Krebs, B.; Hasse, K. D. (1976). "Refinements of the Crystal Structures of KTcO₄, KReO₄ and OsO₄. The Bond Lengths in Tetrahedral Oxo-Anions and Oxides of d⁰ Transition Metals". Acta Crystallographica B. 32 (5): 1334–1337. Bibcode:1976AcCrB..32.1334K. doi:10.1107/S056774087600530X.

[5] "Osmium tetroxide (as Os)". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).

[6] Girolami, Gregory (2012). "Osmium weighs". Nature Chemistry. 4 (11): 954. Bibcode:2012NatCh...4..954G. doi:10.1038/nchem.1479. PMID 23089872.

[7] Cotton and Wilkinson, Advanced Inorganic Chemistry, p.1002

[niosh-8] "Osmium tetroxide (as Os)". Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHs). Centers for Disease Control. 2 November 2018.

[thompson-9] Thompson, M. "Osmium tetroxide (OsO₄)". Bristol University. Retrieved 2012-04-07.

[10] Butler, I. S.; Harrod, J. F. (1989). Inorganic Chemistry: Principles and Applications. Benjamin / Cummings. p. 343. ISBN 978-0-8053-0247-9. Retrieved 2012-04-07.

[11] Cotton, F. A. (2007). Advanced Inorganic Chemistry (6th ed.). New Delhi, India: J. Wiley. p. 1002. ISBN 978-81-265-1338-3.

[h&s-12] Housecroft, C. E.; Sharpe, A. G. (2004). Inorganic Chemistry (2nd ed.). Prentice Hall. pp. 671–673, 710. ISBN 978-0-13-039913-7.

[13] Ogino, Y.; Chen, H.; Kwong, H.-L.; Sharpless, K. B. (1991). "On the timing of hydrolysis / reoxidation in the osmium-catalyzed asymmetric dihydroxylation of olefins using potassium ferricyanide as the reoxidant". Tetrahedron Letters. 32 (32): 3965–3968. doi:10.1016/0040-4039(91)80601-2.

[catalysis-14] Berrisford, D. J.; Bolm, C.; Sharpless, K. B. (1995). "Ligand-Accelerated Catalysis". Angewandte Chemie International Edition. 34 (10): 1059–1070. doi:10.1002/anie.199510591.

[stain-15] Hayat, M. A. (2000). Principles and Techniques of Electron Microscopy: Biological Applications. Cambridge University Press. pp. 45–61. ISBN 0-521-63287-0.

[16] Brian S. McGilligan; John Arnold; Geoffrey Wilkinson; Bilquis Hussain-Bates; Michael B. Hursthouse (1990). "Reactions of Dimesityldioxo-Osmium(VI) with Donor Ligands; Reactions of MO₂(2,4,6-Me₃C₆H₂)₂, M = Os or Re, with Nitrogen Oxides. X-Ray Crystal Structures of [2,4,6-Me₃C₆H₂N₂]⁺[OsO₂(ONO₂)₂(2,4,6-Me₃C₆H₂)]^–, OsO(NBu^t)(2,4,6-Me₃C₆H₂)₂, OsO₃(NBu^t), and ReO₃[N(2,4,6-Me₃C₆H₂)₂]". J. Chem. Soc., Dalton Trans. (8): 2465–2475. doi:10.1039/DT9900002465.

[17] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.

[18] Kiernan, J. A. "Re: "Disposal" of Osmium Tetroxide "Waste"". Department of Anatomy & Cell Biology, The University of Western Ontario.

[19] Christe, K. O.; Dixon, D. A.; Mack, H. G.; Oberhammer, H.; Pagelot, A.; Sanders, J. C. P.; Schrobilgen, G. J. (1993). "Osmium tetrafluoride dioxide, cis-OsO₂F₄". Journal of the American Chemical Society. 115 (24): 11279–11284. doi:10.1021/ja00077a029.

[chem-20] Cotton, S. A. (1997). Chemistry of Precious Metals. London: Chapman and Hall. ISBN 0-7514-0413-6.

[21] Snider, B. B.; Kiselgof, J. Y.; Foxman, B. M. (1998). "Total Syntheses of (±)-Isosteviol and (±)-Beyer-15-ene-3β,19-diol by Manganese(III)-Based Oxidative Quadruple Free-Radical Cyclization". Journal of Organic Chemistry. 63 (22): 7945–7952. doi:10.1021/jo981238x.

[Bozzola-22] Bozzola, J. J.; Russell, L. D. (1999). "Specimen Preparation for Transmission Electron Microscopy". Electron Microscopy: Principles and Techniques for Biologists. Sudbury, MA: Jones and Bartlett. pp. 21–31. ISBN 978-0-7637-0192-5.

[23] Seligman, Arnold M.; Wasserkrug, Hannah L.; Hanker, Jacob S. (1966-08-01). "A new staining method (OTO) for enhancing contrast of lipid--containing membranes and droplets in osmium tetroxide--fixed tissue with osmiophilic thiocarbohydrazide(TCH)". The Journal of Cell Biology. 30 (2): 424–432. doi:10.1083/jcb.30.2.424. ISSN 0021-9525. PMC 2106998. PMID 4165523.

[24] Unger, Ann-Katrin; Neujahr, Ralph; Hawes, Chris; Hummel, Eric (2020), Wacker, Irene; Hummel, Eric; Burgold, Steffen; Schröder, Rasmus (eds.), "Improving Serial Block Face SEM by Focal Charge Compensation", Volume Microscopy : Multiscale Imaging with Photons, Electrons, and Ions, Neuromethods, vol. 155, New York, NY: Springer US, pp. 165–178, doi:10.1007/978-1-0716-0691-9_9, ISBN 978-1-0716-0691-9, S2CID 226563386

[25] Tapia, Juan C.; Kasthuri, Narayanan; Hayworth, Kenneth; Schalek, Richard; Lichtman, Jeff W.; Smith, Stephen J; Buchanan, JoAnn (2012-01-12). "High contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy". Nature Protocols. 7 (2): 193–206. doi:10.1038/nprot.2011.439. ISSN 1754-2189. PMC 3701260. PMID 22240582.

[26] Di Scipio, F.; Raimondo, S.; Tos, P.; Geuna, S. (2008). "A simple protocol for paraffin-embedded myelin sheath staining with osmium(VIII) oxide for light microscope observation". Microscopy Research and Technique. 71 (7): 497–502. doi:10.1002/jemt.20577. PMID 18320578. S2CID 9404999.

[27] Hawkins, J. M.; Meyer, A.; Lewis, T. A.; Loren, S.; Hollander, F. J. (1991). "Crystal Structure of Osmylated C₆₀: Confirmation of the Soccer Ball Framework". Science. 252 (5003): 312–313. Bibcode:1991Sci...252..312H. doi:10.1126/science.252.5003.312. PMID 17769278. S2CID 36255748.

[28] Sheppeard, H.; D. J. Ward (1980). "Intra-articular osmic acid in rheumatoid arthritis: five years' experience". Rheumatology. 19 (1): 25–29. doi:10.1093/rheumatology/19.1.25. PMID 7361025.

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@@ Line 8: / Line 8: @@
 | ImageFileR1 = Osmium-tetroxide-ED-3D-balls-A.png
 | ImageNameR1 = Ball and stick model of osmium tetroxide
-| ImageFile2 = Osmium tetroxide 0.1 gram in ampoule.jpg
+| ImageFile2 = Osmium tetroxide.jpg
 | ImageSize2 = 270px
 | PIN = Osmium tetraoxide
@@ Line 21: / Line 21: @@
 | UNII = P40W033BGM
 | PubChem = 30318
-| PubChem1 = 56370778
-| PubChem1_Comment = (monopotassiate)
-| PubChem2 = 75811001
-| PubChem2_Comment = (monoquinuclidiniate)
-| PubChem3 = 53113021
-| PubChem3_Comment = (monotemediate)
 | ChemSpiderID = 28158
 | ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
-| ChEBI_Ref = {{ebicite|changed|EBI}}
+| ChEBI_Ref = {{ebicite|correct|EBI}}
 | ChEBI = 88215
 | EINECS = 244-058-7
@@ Line 49: / Line 43: @@
 | Density = 4.9{{nbsp}}g/cm<sup>3</sup><ref>{{ cite web | url = http://www.inchem.org/documents/icsc/icsc/eics0528.htm | publisher = InChem | title = Osmium tetroxide ICSC: 0528 }}</ref>
 | MeltingPtC = 40.25
+| BoilingPtC = 129.7<ref>{{cite journal |last1=Koda |first1=Yoshio |date=1986 |title=Boiling Points and Ideal Solutions of Ruthenium and Osmium Tetraoxides |url= |journal=Journal of the Chemical Society, Chemical Communications |volume=1986 |issue=17 |pages=1347–1348 |doi=10.1039/C39860001347 |access-date=}}</ref>
-| BoilingPtC = 129.7
-| Solubility = 5.70{{nbsp}}g/100{{nnbsp}}mL (10&nbsp;°C) <br> 6.23{{nbsp}}g/100{{nnbsp}}mL (25&nbsp;°C)
+| Solubility = 5.70{{nbsp}}g/100{{nbsp}}mL (10&nbsp;°C) <br />6.23{{nbsp}}g/100{{nbsp}}mL (25&nbsp;°C)
 | Solvent1 = carbon tetrachloride{{!}}CCl<sub>4</sub>
-| Solubility1 = 375{{nbsp}}g/100{{nnbsp}}mL
+| Solubility1 = 375{{nbsp}}g/100{{nbsp}}mL
 | SolubleOther = Soluble in most organic solvents, [[ammonium hydroxide]], [[phosphorus oxychloride]]
 | pKa =
@@ Line 58: / Line 52: @@
 }}
 |Section3={{Chembox Structure
+| Structure_ref = <ref name=s1>{{ cite journal |author1=Krebs, B. |author2=Hasse, K. D. | title = Refinements of the Crystal Structures of KTcO<sub>4</sub>, KReO<sub>4</sub> and OsO<sub>4</sub>. The Bond Lengths in Tetrahedral Oxo-Anions and Oxides of d<sup>0</sup> Transition Metals | journal = Acta Crystallographica B | year = 1976 | volume = 32 | issue = 5 | pages = 1334–1337 | doi = 10.1107/S056774087600530X |bibcode=1976AcCrB..32.1334K }}</ref>
 | CrystalStruct = Monoclinic, [[Pearson symbol|mS20]]
+| SpaceGroup = C2/c
-| SpaceGroup = C2/c; {{nowrap|a {{=}} 0.4515 nm}}, {{nowrap|b {{=}} 0.52046 nm}}, {{nowrap|c {{=}} 0.80838 nm}}, {{nowrap|α {{=}} 77.677°}}, {{nowrap|β {{=}} 73.784°}}, {{nowrap|γ {{=}} 64.294°}}<ref name=s1>{{ cite journal |author1=Krebs, B. |author2=Hasse, K. D. | title = Refinements of the Crystal Structures of KTcO<sub>4</sub>, KReO<sub>4</sub> and OsO<sub>4</sub>. The Bond Lengths in Tetrahedral Oxo-Anions and Oxides of d<sup>0</sup> Transition Metals | journal = Acta Crystallographica B | year = 1976 | volume = 32 | issue = 5 | pages = 1334–1337 | doi = 10.1107/S056774087600530X }}</ref>
+| LattConst_a = 9.379&nbsp;[[Angstrom|Å]]
+| LattConst_b = 4.515&nbsp;[[Angstrom|Å]]
+| LattConst_c = 8.630&nbsp;[[Angstrom|Å]]
+| LattConst_beta = 116.58
+| UnitCellVolume = 326.8&nbsp;Å<sup>3</sup>
+| UnitCellFormulas = 4
+| MolShape = tetrahedral
  }}
 |Section7={{Chembox Hazards
 | ExternalSDS = [http://www.inchem.org/documents/icsc/icsc/eics0528.htm ICSC 0528]
+| GHSPictograms = {{GHS05}}{{GHS06}}
-| EUClass = {{Hazchem T+}} ('''T+''')<br/>{{Hazchem C}} ('''C''')
+| GHSSignalWord = Danger
-| RPhrases = {{R26/27/28}}, {{R34}}
+| HPhrases = {{H-phrases|300|310|314|330}}
-| SPhrases = {{S1/2}}, {{S7/9}}, {{S26}}, {{S45}}
+| PPhrases = {{P-phrases|260|262|264|270|271|280|284|301+310|301+330+331|302+350|303+361+353|304+340|305+351+338|310|320|321|322|330|361|363|403+233|405|501}}
 | NFPA-H = 3
 | NFPA-F = 0
@@ Line 77: / Line 80: @@
 |Section8={{Chembox Related
 | OtherAnions =
-| OtherCations = [[Ruthenium tetroxide]]
+| OtherCations = [[Ruthenium tetroxide]]<br />[[Hassium tetroxide]]
 | OtherFunction = [[Osmium(IV) oxide]]
 | OtherFunction_label = [[osmium]] [[oxide]]s
@@ Line 84: / Line 87: @@
 }}
-'''Osmium tetroxide''' (also '''osmium(VIII) oxide''') is the [[chemical compound]] with the [[Chemical formula|formula]] OsO<sub>4</sub>. The compound is noteworthy for its many uses, despite its toxicity and the rarity of [[osmium]]. It also has a number of unusual properties, one being that the solid is [[Volatility (chemistry)|volatile]].  The compound is colourless, but most samples appear yellow.<ref>{{cite journal | last1 = Girolami | first1 = Gregory | year = 2012 | title = Osmium weighs | journal = Nature Chemistry | volume = 4 | issue = 11| page = 954 | doi = 10.1038/nchem.1479 | pmid = 23089872 }}</ref> This is most likely due to the presence of the impurity [[Osmium dioxide|OsO<sub>2</sub>]], which is yellow-brown in colour.<ref>Cotton and Wilkinson, Advanced Inorganic Chemistry, p.1002</ref>
+'''Osmium tetroxide''' (also '''osmium(VIII) oxide''') is the [[chemical compound]] with the [[Chemical formula|formula]] OsO<sub>4</sub>. The compound is noteworthy for its many uses, despite its toxicity and the rarity of [[osmium]]. It also has a number of unusual properties, one being that the solid is [[Volatility (chemistry)|volatile]].  The compound is colourless, but most samples appear yellow.<ref>{{cite journal | last1 = Girolami | first1 = Gregory | year = 2012 | title = Osmium weighs | journal = Nature Chemistry | volume = 4 | issue = 11| page = 954 | doi = 10.1038/nchem.1479 | pmid = 23089872 | bibcode = 2012NatCh...4..954G | doi-access = free }}</ref> This is most likely due to the presence of the impurity [[Osmium dioxide|OsO<sub>2</sub>]], which is yellow-brown in colour.<ref>Cotton and Wilkinson, Advanced Inorganic Chemistry, p.1002</ref> In biology, its property of binding to lipids has made it a widely-used stain in electron microscopy.
 ==Physical properties==
 [[File:OsO4structure.png|thumb|left|Crystal structure of OsO<sub>4</sub><ref name=s1/>]]
-Osmium(VIII) oxide forms [[monoclinic]] crystals.<ref name=s1/><ref name=niosh/> It has a characteristic acrid [[chlorine]]-like odor.  The [[chemical element|element]] name osmium is derived from ''osme'', [[Greek language|Greek]] for ''odor''. OsO<sub>4</sub> is volatile: it [[sublimation (chemistry)|sublimes]] at [[room temperature]]. It is soluble in a wide range of organic solvents.  It is also moderately soluble in water, with which it reacts reversibly to form osmic acid (see below).<ref name=thompson>{{ cite web | author = Thompson, M. | publisher = [[Bristol University]] | title = Osmium tetroxide (OsO<sub>4</sub>) | url = http://www.chm.bris.ac.uk/motm/oso4/oso4h.htm | access-date = 2012-04-07 }}</ref> ''Pure'' osmium(VIII) oxide is probably colourless<ref>{{ cite book |author1=Butler, I. S. |author2=Harrod, J. F. | title = Inorganic Chemistry: Principles and Applications | year = 1989 | publisher = Benjamin / Cummings | isbn = 978-0-8053-0247-9 | page = 343 | url = https://books.google.com/books?id=Nd3vAAAAMAAJ | access-date= 2012-04-07 }}</ref> and it has been suggested that its yellow hue is due to [[osmium dioxide]] (OsO<sub>2</sub>) impurities.<ref>{{ cite book | author = Cotton, F. A. | title = Advanced Inorganic Chemistry | edition = 6th | url = https://books.google.com/books?id=U3MWRONWAmMC | year = 2007 | publisher = J. Wiley | location = New Delhi, India | isbn = 978-81-265-1338-3 | page = 1002 }}</ref> The osmium tetroxide molecule is tetrahedral and therefore non-polar. This nonpolarity helps OsO<sub>4</sub> penetrate charged cell membranes. OsO<sub>4</sub> is 518 times more soluble in [[carbon tetrachloride]] than in water.
+Osmium(VIII) oxide forms [[monoclinic]] crystals.<ref name=s1/><ref name=niosh/> It has a characteristic acrid [[chlorine]]-like odor.  The [[chemical element|element]] name osmium is derived from ''osme'', [[Greek language|Greek]] for ''odor''. OsO<sub>4</sub> is volatile: it [[sublimation (chemistry)|sublimes]] at [[room temperature]]. It is soluble in a wide range of organic solvents. It is moderately soluble in water, with which it reacts reversibly to form osmic acid (see below).<ref name=thompson>{{ cite web | author = Thompson, M. | publisher = [[Bristol University]] | title = Osmium tetroxide (OsO<sub>4</sub>) | url = http://www.chm.bris.ac.uk/motm/oso4/oso4h.htm | access-date = 2012-04-07 }}</ref> ''Pure'' osmium(VIII) oxide is probably colourless;<ref>{{ cite book |author1=Butler, I. S. |author2=Harrod, J. F. | title = Inorganic Chemistry: Principles and Applications | year = 1989 | publisher = Benjamin / Cummings | isbn = 978-0-8053-0247-9 | page = 343 | url = https://books.google.com/books?id=Nd3vAAAAMAAJ | access-date= 2012-04-07 }}</ref> it has been suggested that its yellow hue is attributable due to [[osmium dioxide]] (OsO<sub>2</sub>) impurities.<ref>{{ cite book | author = Cotton, F. A. | title = Advanced Inorganic Chemistry | edition = 6th | url = https://books.google.com/books?id=U3MWRONWAmMC | year = 2007 | publisher = J. Wiley | location = New Delhi, India | isbn = 978-81-265-1338-3 | page = 1002 }}</ref> The osmium tetroxide molecule is tetrahedral and therefore nonpolar. This nonpolarity helps OsO<sub>4</sub> penetrate charged cell membranes.
 ==Structure and electron configuration==
-The [[osmium]] of OsO<sub>4</sub> has an [[oxidation number]] of VIII; however, the metal does not possess a corresponding 8+ charge as the bonding in the compound is largely [[covalent]] in character (the [[ionization energy]] required to produce a formal 8+ charge also far exceeds the energies available in normal chemical reactions). The osmium atom has eight [[valence shell|valence]] electrons (6s<sup>2</sup>, 5d<sup>6</sup>) with double bonds to the four [[oxide]] [[ligands]] resulting in a [[16-Electron Complexes#16e complexes|16 electron complex]]. This is isoelectronic with [[permanganate]] and [[Chromate ion|chromate]] ions.
+The [[osmium]] of OsO<sub>4</sub> has an [[oxidation number]] of VIII; however, the metal does not possess a corresponding 8+ charge as the bonding in the compound is largely [[covalent]] in character (the [[ionization energy]] required to produce a formal 8+ charge also far exceeds the energies available in normal chemical reactions). The osmium atom exhibits double bonds to the four [[oxide]] [[ligands]], resulting in a [[16-Electron Complexes#16e complexes|16 electron complex]]. OsO<sub>4</sub> is isoelectronic with [[permanganate]] and [[Chromate ion|chromate]] ions.
 ==Synthesis==
@@ Line 102: / Line 105: @@
 ===Oxidation of alkenes===
-Alkenes add to OsO<sub>4</sub> to give [[alkoxide|diolate]] species that hydrolyze to ''cis''-diols.  The net process is called dihydroxylation. This proceeds via a [3 + 2] [[cycloaddition]] reaction between the OsO<sub>4</sub> and alkene to form an intermediate osmate ester which rapidly hydrolyses to yield the [[Diol#Vicinal diols|vicinal diol]]. As the oxygen atoms are added in a concerted step, the resulting stereochemistry is ''[[Cis-trans isomerism|cis]]''.
+Alkenes add to OsO<sub>4</sub> to give [[alkoxide|diolate]] species that hydrolyze to ''cis''-diols. The net process is called dihydroxylation. This proceeds via a [3 + 2] [[cycloaddition]] reaction between the OsO<sub>4</sub> and alkene to form an intermediate osmate ester that rapidly hydrolyses to yield the [[Diol#Vicinal diols|vicinal diol]]. As the oxygen atoms are added in a concerted step, the resulting stereochemistry is ''[[Cis-trans isomerism|cis]]''.
 :[[File:Dihydroxylation with OsO4.png|thumb|center|600px|Idealized depiction of the cis-dihydroxylation of alkenes.]]
-OsO<sub>4</sub> is expensive and highly toxic, making it an unappealing reagent to use in [[stoichiometric]] amounts. However its reactions are made  [[Catalysis|catalytic]] by adding [[reoxidant]]s to reoxidise the Os(VI) by-product back to Os(VIII).  Typical reagents include [[hydrogen peroxide|H<sub>2</sub>O<sub>2</sub>]] ([[Milas hydroxylation]]), [[N-Methylmorpholine N-oxide|N-methylmorpholine N-oxide]] ([[Upjohn dihydroxylation]]) and [[potassium ferricyanide|K<sub>3</sub>Fe(CN)<sub>6</sub>]]/water.  These reoxidants do not react with the alkenes on their own. Other osmium compounds can be used as catalysts, including osmate(VI) salts ([OsO<sub>2</sub>(OH)<sub>4</sub>)]<sup>2−</sup>, and osmium trichloride hydrate (OsCl<sub>3</sub>·''x''H<sub>2</sub>O). These species oxidise to osmium(VIII) in the presence of such oxidants.<ref>{{ cite journal | title = On the timing of hydrolysis / reoxidation in the osmium-catalyzed asymmetric dihydroxylation of olefins using potassium ferricyanide as the reoxidant |author1=Ogino, Y. |author2=Chen, H. |author3=Kwong, H.-L. |author4=Sharpless, K. B. | journal = [[Tetrahedron Letters]] | year = 1991 | volume = 32 | issue = 32 | pages = 3965–3968 | doi = 10.1016/0040-4039(91)80601-2 }}</ref>
+OsO<sub>4</sub> is expensive and highly toxic, making it an unappealing reagent to use in [[stoichiometric]] amounts. However, its reactions are made  [[Catalysis|catalytic]] by adding [[reoxidant]]s to reoxidise the Os(VI) by-product back to Os(VIII). Typical reagents include [[hydrogen peroxide|H<sub>2</sub>O<sub>2</sub>]] ([[Milas hydroxylation]]), [[N-Methylmorpholine N-oxide|N-methylmorpholine N-oxide]] ([[Upjohn dihydroxylation]]) and [[potassium ferricyanide|K<sub>3</sub>Fe(CN)<sub>6</sub>]]/water. These reoxidants do not react with the alkenes on their own. Other osmium compounds can be used as catalysts, including osmate(VI) salts ([OsO<sub>2</sub>(OH)<sub>4</sub>)]<sup>2−</sup>, and osmium trichloride hydrate (OsCl<sub>3</sub>·''x''H<sub>2</sub>O). These species oxidise to osmium(VIII) in the presence of such oxidants.<ref>{{ cite journal | title = On the timing of hydrolysis / reoxidation in the osmium-catalyzed asymmetric dihydroxylation of olefins using potassium ferricyanide as the reoxidant |author1=Ogino, Y. |author2=Chen, H. |author3=Kwong, H.-L. |author4=Sharpless, K. B. | journal = [[Tetrahedron Letters]] | year = 1991 | volume = 32 | issue = 32 | pages = 3965–3968 | doi = 10.1016/0040-4039(91)80601-2 }}</ref>
 Lewis bases such as tertiary [[amine]]s and [[pyridine]]s increase the rate of dihydroxylation. This "ligand-acceleration" arises via the formation of [[adduct]] OsO<sub>4</sub>L, which adds more rapidly to the alkene. If the amine is chiral, then the dihydroxylation can proceed with enantioselectivity (see [[Sharpless asymmetric dihydroxylation]]).<ref name=catalysis>{{ cite journal |author1=Berrisford, D. J. |author2=Bolm, C. |author3=Sharpless, K. B. | title = Ligand-Accelerated Catalysis | year = 1995 | journal = [[Angewandte Chemie International Edition]] | volume = 34 | issue = 10 | pages = 1059–1070 | doi = 10.1002/anie.199510591 }}</ref> OsO<sub>4</sub> does not react with most carbohydrates.<ref name=stain/>
@@ Line 115: / Line 118: @@
 ===Coordination chemistry===
-[[File:CSD CIF KEWMEE.png|thumb|144px|left|Structure of OsO<sub>3</sub>(N-t-Bu) (multiple bonds are not drawn explicitly), illustrating the type of osmium(VIII)-oxo-imide that adds alkenes en route to the amino alcohol.<ref>{{cite journal|title=Reactions of Dimesityldioxo-Osmium(VI) with Donor Ligands; Reactions of MO<sub>2</sub>(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub>, M = Os or Re, with Nitrogen Oxides. X-Ray Crystal Structures of [2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>N<sub>2</sub>]<sup>+</sup>[OsO<sub>2</sub>(ONO<sub>2</sub>)<sub>2</sub>(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)]<sup>–</sup>, OsO(NBu<sup>t</sup>)(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub>, OsO<sub>3</sub>(NBu<sup>t</sup>), and ReO<sub>3</sub>[N(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub>]|authors=Brian S. McGilligan, John Arnold, Geoffrey Wilkinson, Bilquis Hussain-Bates, Michael B. Hursthouse|journal=J. Chem. Soc., Dalton Trans.|year=1990|issue=8|pages=2465–2475 |doi=10.1039/DT9900002465}}</ref>]]OsO<sub>4</sub> is a [[Lewis acid]] and a mild oxidant. It reacts with alkaline [[aqueous solution]] to give the perosmate anion {{chem|OsO|4|(OH)|2|2−}}.<ref>{{Greenwood&Earnshaw2nd}}</ref> This species is easily reduced to [[potassium osmate|osmate]] anion, {{chem|OsO|2|(OH)|4|2-}}.
+[[File:CSD CIF KEWMEE.png|thumb|144px|left|Structure of OsO<sub>3</sub>(N-t-Bu) (multiple bonds are not drawn explicitly), illustrating the type of osmium(VIII)-oxo-imide that adds alkenes en route to the amino alcohol.<ref>{{cite journal|title=Reactions of Dimesityldioxo-Osmium(VI) with Donor Ligands; Reactions of MO<sub>2</sub>(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub>, M = Os or Re, with Nitrogen Oxides. X-Ray Crystal Structures of [2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>N<sub>2</sub>]<sup>+</sup>[OsO<sub>2</sub>(ONO<sub>2</sub>)<sub>2</sub>(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)]<sup>–</sup>, OsO(NBu<sup>t</sup>)(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub>, OsO<sub>3</sub>(NBu<sup>t</sup>), and ReO<sub>3</sub>[N(2,4,6-Me<sub>3</sub>C<sub>6</sub>H<sub>2</sub>)<sub>2</sub>]|author=Brian S. McGilligan |author2=John Arnold |author3=Geoffrey Wilkinson |author4=Bilquis Hussain-Bates |author5=Michael B. Hursthouse |journal=J. Chem. Soc., Dalton Trans.|year=1990|issue=8|pages=2465–2475 |doi=10.1039/DT9900002465}}</ref>]]OsO<sub>4</sub> is a [[Lewis acid]] and a mild oxidant. It reacts with alkaline [[aqueous solution]] to give the perosmate anion {{chem|OsO|4|(OH)|2|2−}}.<ref>{{Greenwood&Earnshaw2nd}}</ref> This species is easily reduced to [[potassium osmate|osmate]] anion, {{chem|OsO|2|(OH)|4|2-}}.
 When the [[Lewis base]] is an [[amine]], adducts are also formed.  Thus OsO<sub>4</sub> can be stored in the form of '''osmeth''', in which OsO<sub>4</sub> is [[complexation|complexed]] with [[hexamine]]. Osmeth can be dissolved in [[tetrahydrofuran]] (THF) and diluted in an aqueous [[buffer solution]] to make a dilute (0.25%) working [[Solution (chemistry)|solution]] of OsO<sub>4</sub>.<ref>{{ cite web | author = Kiernan, J. A. | publisher = Department of Anatomy & Cell Biology, The University of Western Ontario | url = http://www.histosearch.com/histonet/Nov00A/Re.quotDisposalquotofOsmi.html | title = Re: "Disposal" of Osmium Tetroxide "Waste" }}</ref>
@@ Line 125: / Line 128: @@
 The [Os(N)O<sub>3</sub>]<sup>−</sup> anion is isoelectronic and isostructural with OsO<sub>4</sub>.
-OsO<sub>4</sub> is very soluble in [[tert-butyl alcohol]]. In solution, it is readily reduced by hydrogen to osmium metal. The suspended osmium metal can be used to [[catalysis|catalyze]] [[hydrogenation]] of a wide variety of organic chemicals containing double or triple bonds.
+OsO<sub>4</sub> is very soluble in [[tert-butyl alcohol]]. In solution, it is readily reduced by hydrogen to osmium metal. The suspended osmium metal can be used to [[catalysis|catalytically]] [[hydrogenation|hydrogenate]] a wide variety of organic chemicals containing double or triple bonds.
 :OsO<sub>4</sub> + 4 H<sub>2</sub> → Os  + 4 H<sub>2</sub>O
@@ Line 159: / Line 162: @@
-OsO<sub>4</sub> is a widely used [[staining]] agent used in [[transmission electron microscopy]] (TEM) to provide contrast to the image.<ref name="Bozzola">{{ cite book |author1=Bozzola, J. J. |author2=Russell, L. D. | chapter = Specimen Preparation for Transmission Electron Microscopy | title = Electron Microscopy : Principles and Techniques for Biologists | year = 1999 | publisher = Jones and Bartlett | location = Sudbury, MA | pages = 21–31 | isbn = 978-0-7637-0192-5 | chapter-url = https://books.google.com/books?id=RqSMzR-IXk0C&pg=PA21 }}</ref> As a [[lipid]] stain, it is also useful in [[scanning electron microscopy]] (SEM) as an alternative to [[sputter coating]]. It embeds a heavy metal directly into cell membranes, creating a high electron scattering rate without the need for coating the membrane with a layer of metal, which can obscure details of the cell membrane. In the staining of the [[plasma membrane]], osmium(VIII) oxide binds [[phospholipid]] head regions, thus creating contrast with the neighbouring [[protoplasm]] (cytoplasm). Additionally, osmium(VIII) oxide is also used for fixing biological samples in conjunction with HgCl<sub>2</sub>. Its rapid killing abilities are used to quickly kill live specimens such as protozoa. OsO<sub>4</sub> stabilizes many proteins by transforming them into gels without destroying structural features. Tissue proteins that are stabilized by OsO<sub>4</sub> are not coagulated by alcohols during dehydration.<ref name=stain>{{ cite book | author = Hayat, M. A. | title = Principles and Techniques of Electron Microscopy: Biological Applications | publisher = Cambridge University Press | year = 2000 | pages = 45–61 | isbn = 0-521-63287-0 | url = https://books.google.com/books?id=nfsVMH8it1kC }}</ref> Osmium(VIII) oxide is also used as a stain for lipids in optical microscopy.<ref>{{ cite journal | title = A simple protocol for paraffin-embedded myelin sheath staining with osmium(VIII) oxide for light microscope observation |author1=Di Scipio, F. |author2=Raimondo, S. |author3=Tos, P. |author4=Geuna, S. | journal = Microscopy Research and Technique | year = 2008 | volume = 71 | issue = 7 | pages = 497–502 | doi = 10.1002/jemt.20577 | pmid = 18320578 |s2cid=9404999 }}</ref> OsO<sub>4</sub> also stains the human cornea (see [[Osmium tetroxide#Safety considerations|safety considerations]]).
+OsO<sub>4</sub> is a widely used [[staining]] agent used in [[transmission electron microscopy]] (TEM) to provide contrast to the image.<ref name="Bozzola">{{ cite book |author1=Bozzola, J. J. |author2=Russell, L. D. | chapter = Specimen Preparation for Transmission Electron Microscopy | title = Electron Microscopy: Principles and Techniques for Biologists | year = 1999 | publisher = Jones and Bartlett | location = Sudbury, MA | pages = 21–31 | isbn = 978-0-7637-0192-5 | chapter-url = https://books.google.com/books?id=RqSMzR-IXk0C&pg=PA21 }}</ref> This staining method may also be known in the literature as the OTO<ref>{{Cite journal|last1=Seligman|first1=Arnold M.|last2=Wasserkrug|first2=Hannah L.|last3=Hanker|first3=Jacob S.|title=A new staining method (OTO) for enhancing contrast of lipid--containing membranes and droplets in osmium tetroxide--fixed tissue with osmiophilic thiocarbohydrazide(TCH)|date=1966-08-01|journal=The Journal of Cell Biology|volume=30|issue=2|pages=424–432|doi=10.1083/jcb.30.2.424|issn=0021-9525|pmc=2106998|pmid=4165523}}</ref><ref>{{Citation |last1=Unger |first1=Ann-Katrin |date=2020 |work=Volume Microscopy : Multiscale Imaging with Photons, Electrons, and Ions |pages=165–178 |editor-last=Wacker |editor-first=Irene |place=New York, NY |publisher=Springer US |language=en |doi=10.1007/978-1-0716-0691-9_9 |isbn=978-1-0716-0691-9 |last2=Neujahr |first2=Ralph |last3=Hawes |first3=Chris |last4=Hummel |first4=Eric |title=Improving Serial Block Face SEM by Focal Charge Compensation |series=Neuromethods |volume=155 |s2cid=226563386 |editor2-last=Hummel |editor2-first=Eric |editor3-last=Burgold |editor3-first=Steffen |editor4-last=Schröder |editor4-first=Rasmus}}</ref> (osmium-thiocarbohydrazide-osmium) method, or osmium impregnation<ref>{{Cite journal|last1=Tapia|first1=Juan C.|last2=Kasthuri|first2=Narayanan|last3=Hayworth|first3=Kenneth|last4=Schalek|first4=Richard|last5=Lichtman|first5=Jeff W.|last6=Smith|first6=Stephen J|last7=Buchanan|first7=JoAnn|date=2012-01-12|title=High contrast en bloc staining of neuronal tissue for field emission scanning electron microscopy|journal=Nature Protocols|volume=7|issue=2|pages=193–206|doi=10.1038/nprot.2011.439|issn=1754-2189|pmc=3701260|pmid=22240582}}</ref> technique or simply as osmium staining. As a [[lipid]] stain, it is also useful in [[scanning electron microscopy]] (SEM) as an alternative to [[sputter coating]]. It embeds a heavy metal directly into cell membranes, creating a high electron scattering rate without the need for coating the membrane with a layer of metal, which can obscure details of the cell membrane. In the staining of the [[plasma membrane]], osmium(VIII) oxide binds [[phospholipid]] head regions, thus creating contrast with the neighbouring [[protoplasm]] (cytoplasm). Additionally, osmium(VIII) oxide is also used for fixing biological samples in conjunction with HgCl<sub>2</sub>. Its rapid killing abilities are used to quickly kill live specimens such as protozoa. OsO<sub>4</sub> stabilizes many proteins by transforming them into gels without destroying structural features. Tissue proteins that are stabilized by OsO<sub>4</sub> are not coagulated by alcohols during dehydration.<ref name=stain>{{ cite book | author = Hayat, M. A. | title = Principles and Techniques of Electron Microscopy: Biological Applications | publisher = Cambridge University Press | year = 2000 | pages = 45–61 | isbn = 0-521-63287-0 | url = https://books.google.com/books?id=nfsVMH8it1kC }}</ref> Osmium(VIII) oxide is also used as a stain for lipids in optical microscopy.<ref>{{ cite journal | title = A simple protocol for paraffin-embedded myelin sheath staining with osmium(VIII) oxide for light microscope observation |author1=Di Scipio, F. |author2=Raimondo, S. |author3=Tos, P. |author4=Geuna, S. | journal = Microscopy Research and Technique | year = 2008 | volume = 71 | issue = 7 | pages = 497–502 | doi = 10.1002/jemt.20577 | pmid = 18320578 |s2cid=9404999 }}</ref> OsO<sub>4</sub> also stains the human cornea (see [[Osmium tetroxide#Safety considerations|safety considerations]]).
 [[File:Resin-Embedded Transmission Electron Microscope Sample.jpg|thumb|left|A sample of cells fixed/stained with osmium tetroxide (black) embedded in epoxy resin (amber). The cells are black as a result of the effects of osmium tetroxide.]]
@@ Line 170: / Line 173: @@
 ===Buckminsterfullerene adduct===
-OsO<sub>4</sub> allowed for the confirmation of the soccer ball model of [[buckminsterfullerene]], a 60-atom [[carbon]] [[allotrope]]. The [[adduct]], formed from a derivative of OsO<sub>4</sub>, was C<sub>60</sub>(OsO<sub>4</sub>)(4-''tert''-[[butyl]][[pyridine]])<sub>2</sub>. The adduct broke the fullerene's symmetry, allowing for crystallization and confirmation of the structure of C<sub>60</sub> by [[X-ray crystallography]].<ref>{{ cite journal |author1=Hawkins, J. M. |author2=Meyer, A. |author3=Lewis, T. A. |author4=Loren, S. |author5=Hollander, F. J. | title = Crystal Structure of Osmylated C<sub>60</sub>: Confirmation of the Soccer Ball Framework | year = 1991 | journal = [[Science (journal)|Science]] | volume = 252 | issue = 5003 | pages = 312–313 | doi = 10.1126/science.252.5003.312 | pmid = 17769278 |s2cid=36255748 }}</ref>
+OsO<sub>4</sub> allowed for the confirmation of the soccer ball model of [[buckminsterfullerene]], a 60-atom [[carbon]] [[allotrope]]. The [[adduct]], formed from a derivative of OsO<sub>4</sub>, was C<sub>60</sub>(OsO<sub>4</sub>)(4-''tert''-[[butyl]][[pyridine]])<sub>2</sub>. The adduct broke the fullerene's symmetry, allowing for crystallization and confirmation of the structure of C<sub>60</sub> by [[X-ray crystallography]].<ref>{{ cite journal |author1=Hawkins, J. M. |author2=Meyer, A. |author3=Lewis, T. A. |author4=Loren, S. |author5=Hollander, F. J. | title = Crystal Structure of Osmylated C<sub>60</sub>: Confirmation of the Soccer Ball Framework | year = 1991 | journal = [[Science (journal)|Science]] | volume = 252 | issue = 5003 | pages = 312–313 | doi = 10.1126/science.252.5003.312 | pmid = 17769278 |bibcode=1991Sci...252..312H |s2cid=36255748 }}</ref>
+===Medicine===
-==Safety considerations==
+The only known clinical use of osmium tetroxide is for the treatment of arthritis.<ref>{{cite journal|last=Sheppeard|first=H.|author2=D. J. Ward|journal=Rheumatology|date=1980|volume=19|pages=25–29|doi=10.1093/rheumatology/19.1.25|pmid=7361025|title=Intra-articular osmic acid in rheumatoid arthritis: five years' experience|issue=1}}</ref> The lack of reports of long-term side effects from the local administration of osmium tetroxide (OsO<sub>4</sub>) suggest that osmium itself can be [[biocompatible]], though this depends on the osmium compound administered.
-[[File:Label for ampoules of OsO4.jpg|thumb|right|300px|Label with poison warning]]OsO<sub>4</sub> is highly poisonous. In particular, inhalation at concentrations well below those at which a smell can be perceived can lead to [[pulmonary edema]] and subsequent death. Noticeable symptoms can take hours to appear after exposure.{{cn|date=September 2019}}
-OsO<sub>4</sub> will irreversibly stain the human [[cornea]], which can lead to blindness. The permissible exposure limit for osmium(VIII) oxide (8 hour time-weighted average) is 2&nbsp;µg/m<sup>3</sup>.<ref name=niosh>{{ cite web | url = https://www.cdc.gov/niosh/idlh/20816120.html | title = Osmium tetroxide (as Os) | work = Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHs)| publisher = Centers for Disease Control }}</ref> Osmium(VIII) oxide can penetrate plastics and food packaging, and therefore must be stored in glass under refrigeration.<ref name=stain/>
+==Safety considerations==
-On April 6, 2004 British intelligence sources believed they had foiled a plot by [[al-Qaeda]] sympathisers to detonate a bomb involving OsO<sub>4</sub>.<ref>{{cite news | title = Chemical 'bomb plot' in UK foiled | url = http://news.bbc.co.uk/1/hi/uk/3603961.stm | work = [[BBC News]] | date = 2004-04-06 }}</ref> Experts interviewed by ''[[New Scientist]]'' affirmed osmium(VIII) oxide's toxicity, although some highlighted the difficulties of using it in a weapon: osmium(VIII) oxide is very expensive, it may be destroyed by the blast, and remaining toxic fumes may also be dispersed by the blast.<ref>{{cite magazine | url = https://www.newscientist.com/article/dn4863-experts-divided-over-poison-bomb-claim.html | magazine = [[New Scientist]] | title = Experts divided over poison bomb claim | author = Bhattacharya, S. | date = 2004-04-07 }}</ref>
+[[File:Label for ampoules of OsO4.jpg|thumb|right|300px|Label with poison warning]]
+OsO<sub>4</sub> will irreversibly stain the human [[cornea]], which can lead to blindness. The permissible exposure limit for osmium(VIII) oxide (8 hour time-weighted average) is 2&nbsp;μg/m<sup>3</sup>.<ref name=niosh>{{ cite web | url = https://www.cdc.gov/niosh/idlh/20816120.html | title = Osmium tetroxide (as Os) | work = Documentation for Immediately Dangerous to Life or Health Concentrations (IDLHs)| date = 2 November 2018 | publisher = Centers for Disease Control }}</ref> Osmium(VIII) oxide can penetrate plastics and food packaging, and therefore must be stored in glass under refrigeration.<ref name=stain/>
 ==References==

v t e Oxides
Mixed oxidation states	Antimony tetroxide (Sb₂O₄) Boron suboxide (B₁₂O₂) Carbon suboxide (C₃O₂) Chlorine perchlorate (Cl₂O₄) Chloryl perchlorate (Cl₂O₆) Cobalt(II,III) oxide (Co₃O₄) Dichlorine pentoxide (Cl₂O₅) Iron(II,III) oxide (Fe₃O₄) Lead(II,IV) oxide (Pb₃O₄) Manganese(II,III) oxide (Mn₃O₄) Mellitic anhydride (C₁₂O₉) Praseodymium(III,IV) oxide (Pr₆O₁₁) Silver(I,III) oxide (Ag₂O₂) Terbium(III,IV) oxide (Tb₄O₇) Tribromine octoxide (Br₃O₈) Triuranium octoxide (U₃O₈)
+1 oxidation state	Aluminium(I) oxide (Al₂O) Copper(I) oxide (Cu₂O) Caesium monoxide (Cs₂O) Dibromine monoxide (Br₂O) Dicarbon monoxide (C₂O) Dichlorine monoxide (Cl₂O) Gallium(I) oxide (Ga₂O) Iodine(I) oxide (I₂O) Lithium oxide (Li₂O) Mercury(I) oxide (Hg₂O) Nitrous oxide (N₂O) Potassium oxide (K₂O) Rubidium oxide (Rb₂O) Silver oxide (Ag₂O) Thallium(I) oxide (Tl₂O) Sodium oxide (Na₂O) Water (hydrogen oxide) (H₂O)
+2 oxidation state	Aluminium(II) oxide (AlO) Barium oxide (BaO) Berkelium monoxide (BkO) Beryllium oxide (BeO) Boron monoxide (BO) Bromine monoxide (BrO) Cadmium oxide (CdO) Calcium oxide (CaO) Carbon monoxide (CO) Chlorine monoxide (ClO) Chromium(II) oxide (CrO) Cobalt(II) oxide (CoO) Copper(II) oxide (CuO) Dinitrogen dioxide (N₂O₂) Europium(II) oxide (EuO) Germanium monoxide (GeO) Iron(II) oxide (FeO) Iodine monoxide (IO) Lead(II) oxide (PbO) Magnesium oxide (MgO) Manganese(II) oxide (MnO) Mercury(II) oxide (HgO) Nickel(II) oxide (NiO) Nitric oxide (NO) Niobium monoxide (NbO) Palladium(II) oxide (PdO) Phosphorus monoxide (PO) Polonium monoxide (PoO) Protactinium monoxide (PaO) Radium oxide (RaO) Silicon monoxide (SiO) Strontium oxide (SrO) Sulfur monoxide (SO) Disulfur dioxide (S₂O₂) Thorium monoxide (ThO) Tin(II) oxide (SnO) Titanium(II) oxide (TiO) Vanadium(II) oxide (VO) Yttrium(II) oxide (YO) Zirconium monoxide (ZrO) Zinc oxide (ZnO)
+3 oxidation state	Actinium(III) oxide (Ac₂O₃) Aluminium oxide (Al₂O₃) Americium(III) oxide (Am₂O₃) Antimony trioxide (Sb₂O₃) Arsenic trioxide (As₂O₃) Berkelium(III) oxide (Bk₂O₃) Bismuth(III) oxide (Bi₂O₃) Boron trioxide (B₂O₃) Caesium sesquioxide (Cs₂O₃) Californium(III) oxide (Cf₂O₃) Cerium(III) oxide (Ce₂O₃) Chromium(III) oxide (Cr₂O₃) Cobalt(III) oxide (Co₂O₃) Dinitrogen trioxide (N₂O₃) Dysprosium(III) oxide (Dy₂O₃) Einsteinium(III) oxide (Es₂O₃) Erbium(III) oxide (Er₂O₃) Europium(III) oxide (Eu₂O₃) Gadolinium(III) oxide (Gd₂O₃) Gallium(III) oxide (Ga₂O₃) Gold(III) oxide (Au₂O₃) Holmium(III) oxide (Ho₂O₃) Indium(III) oxide (In₂O₃) Iron(III) oxide (Fe₂O₃) Lanthanum oxide (La₂O₃) Lutetium(III) oxide (Lu₂O₃) Manganese(III) oxide (Mn₂O₃) Neodymium(III) oxide (Nd₂O₃) Nickel(III) oxide (Ni₂O₃) Phosphorus trioxide (P₄O₆) Praseodymium(III) oxide (Pr₂O₃) Promethium(III) oxide (Pm₂O₃) Rhodium(III) oxide (Rh₂O₃) Samarium(III) oxide (Sm₂O₃) Scandium oxide (Sc₂O₃) Terbium(III) oxide (Tb₂O₃) Thallium(III) oxide (Tl₂O₃) Thulium(III) oxide (Tm₂O₃) Titanium(III) oxide (Ti₂O₃) Tungsten(III) oxide (W₂O₃) Vanadium(III) oxide (V₂O₃) Ytterbium(III) oxide (Yb₂O₃) Yttrium(III) oxide (Y₂O₃)
+4 oxidation state	Americium dioxide (AmO₂) Berkelium(IV) oxide (BkO₂) Bromine dioxide (BrO₂) Californium dioxide (CfO₂) Carbon dioxide (CO₂) Carbon trioxide (CO₃) Cerium(IV) oxide (CeO₂) Chlorine dioxide (ClO₂) Chromium(IV) oxide (CrO₂) Curium(IV) oxide (CmO₂) Dinitrogen tetroxide (N₂O₄) Germanium dioxide (GeO₂) Iodine dioxide (IO₂) Iridium dioxide (IrO₂) Hafnium(IV) oxide (HfO₂) Lead dioxide (PbO₂) Manganese dioxide (MnO₂) Molybdenum dioxide (MoO₂) Neptunium(IV) oxide (NpO₂) Nitrogen dioxide (NO₂) Niobium dioxide (NbO₂) Osmium dioxide (OsO₂) Platinum dioxide (PtO₂) Plutonium(IV) oxide (PuO₂) Polonium dioxide (PoO₂) Praseodymium(IV) oxide (PrO₂) Protactinium(IV) oxide (PaO₂) Rhenium(IV) oxide (ReO₂) Rhodium(IV) oxide (RhO₂) Ruthenium(IV) oxide (RuO₂) Selenium dioxide (SeO₂) Silicon dioxide (SiO₂) Sulfur dioxide (SO₂) Technetium(IV) oxide (TcO₂) Tellurium dioxide (TeO₂) Terbium(IV) oxide (TbO₂) Thorium dioxide (ThO₂) Tin dioxide (SnO₂) Titanium dioxide (TiO₂) Tungsten(IV) oxide (WO₂) Uranium dioxide (UO₂) Vanadium(IV) oxide (VO₂) Zirconium dioxide (ZrO₂)
+5 oxidation state	Antimony pentoxide (Sb₂O₅) Arsenic pentoxide (As₂O₅) Bismuth pentoxide (Bi₂O₅) Dinitrogen pentoxide (N₂O₅) Niobium pentoxide (Nb₂O₅) Phosphorus pentoxide (P₂O₅) Protactinium(V) oxide (Pa₂O₅) Tantalum pentoxide (Ta₂O₅) Tungsten pentoxide (W₂O₅) Vanadium(V) oxide (V₂O₅)
+6 oxidation state	Chromium trioxide (CrO₃) Molybdenum trioxide (MoO₃) Polonium trioxide (PoO₃) Rhenium trioxide (ReO₃) Selenium trioxide (SeO₃) Sulfur trioxide (SO₃) Tellurium trioxide (TeO₃) Tungsten trioxide (WO₃) Uranium trioxide (UO₃) Xenon trioxide (XeO₃)
+7 oxidation state	Dichlorine heptoxide (Cl₂O₇) Manganese heptoxide (Mn₂O₇) Rhenium(VII) oxide (Re₂O₇) Technetium(VII) oxide (Tc₂O₇)
+8 oxidation state	Iridium tetroxide (IrO₄) Osmium tetroxide (OsO₄) Ruthenium tetroxide (RuO₄) Xenon tetroxide (XeO₄) Hassium tetroxide (HsO₄)
Related	Oxocarbon Suboxide Oxyanion Ozonide Peroxide Superoxide Oxypnictide
Oxides are sorted by oxidation state. Category:Oxides