Osmium (VIII) oxide

Crystal structure
	__ Os 8+ __ O 2−
Crystal system	monoclinic
Space group	C 2 / c (No. 15)
Lattice parameters	a = 938 pm, b = 452 pm, c = 863 pm, β = 116.58 °
General
Surname	Osmium (VIII) oxide
other names	Osmium tetroxide; Osmic acid;
Ratio formula	OsO 4
Brief description	colorless, monoclinic needles with a pungent odor
External identifiers / databases
EC number	244-058-7
ECHA InfoCard	100.040.038
PubChem	30318
Wikidata	Q422021
properties
Molar mass	254.23 g mol −1
Physical state	firmly
density	4.91 g cm −3
Melting point	40 ° C
boiling point	130 ° C
Vapor pressure	10 h Pa (20 ° C)
solubility	moderate in water (65 g l −1 ); good in many organic solvents, e.g. B. carbon tetrachloride , ethanol , diethyl ether and benzene ;
safety instructions
H and P phrases	H: 300 + 310 + 330-314
	P: 280-301 + 330 + 331-302 + 352-304 + 340-305 + 351 + 338-308 + 310
MAK	Switzerland: 0.2 μl m −3 or 2 μg m −3 (calculated as osmium)
Toxicological data	15 mg kg −1 ( LD 50 , rat , oral )
Thermodynamic properties
ΔH f 0	−386 kJ mol −1
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Osmium (VIII) oxide (also: osmic acid) is the oxide of the element osmium in its highest oxidation state (+8).

Presentation and extraction

Osmium (VIII) oxide is produced from osmium metal by oxidizing osmium solutions with nitric acid or sodium peroxodisulfate in sulfuric acid. Because of its volatility and toxicity, it is sold melted in ampoules .

1 g osmium tetroxide in an ampoule

properties

Physical Properties

Osmium (VIII) oxide forms pale yellow crystals with a very low melting point of 40 ° C and a boiling point of 130 ° C. This compound has a penetrating ozone-like odor ( ancient Greek ὀσμή osmē “smell, stench”), which explains the name given to the metal osmium. Osmium (VIII) oxide has a monoclinic crystal structure with the space group C 2 / c (space group no. 15) . The lattice parameters are a = 938 pm, b = 452 pm, c = 863 pm and β = 116.58 °. It dissolves only moderately in water, but very well in carbon tetrachloride CCl ₄ . Template: room group / 15

Chemical properties

Osmium (VIII) oxide is a strong oxidizing agent and reacts with reducing and combustible substances. It is easily reduced to black osmium (IV) oxide by organic compounds .

use

In organic synthesis it can be used to oxidize alkenes to diols ( dihydroxylation ). This stereoselectively produces a diol with cis OH groups. Since the reagent is very expensive and toxic, the reaction conditions have now been improved so that osmium (VIII) oxide in small quantities as a catalyst is required, while hydrogen peroxide or N -Methylmorpholin- N oxide as oxidant effect.

For transmission electron microscopy (TEM), typically 1% osmium tetroxide solution is used to fix and contrast samples made from biological material. Lipids, in particular, are colored black.

Others

On April 6, 2004 the American news agency ABC News reported that the British secret service believed they had thwarted a bomb attack using this substance. Other sources doubt this representation, as osmium (VIII) oxide is too expensive for use as a poison gas, despite its high damage potential .

On May 27, 2011, an accident occurred at the Magdeburg University Hospital: A bottle with 20–50 ml of 2% osmium tetroxide solution broke. This did not harm people, but house 1 had to be partially evacuated. The fire brigade cleaned the scene of the accident.

Individual evidence

↑ ^a ^b entry on osmium tetroxide. In: Römpp Online . Georg Thieme Verlag, accessed on July 18, 2011.
↑ ^a ^b ^c ^d Entry on osmium (VIII) oxide in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
↑ ^a ^b ^c ^d ^e ^f data sheet osmium (VIII) oxide (PDF) from Merck , accessed on January 19, 2011.
↑ Entry on Osmium tetraoxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 20816-12-0 or osmium (VIII) oxide ), accessed on November 2, 2015.
^ AF Holleman , N. Wiberg : Inorganische Chemie . 103rd edition. Volume 2: Subgroup elements, lanthanoids, actinides, transactinides. Walter de Gruyter, Berlin / Boston 2016, ISBN 978-3-11-049590-4 , p. 1975 (reading sample: Part C - Subgroup elements. Google book search ).
^ B. Krebs, K. Hasse: Refinements of the crystal structures of KTcO ₄ , KReO ₄ and OsO ₄ . Bond lengths in tetrahedral oxo-anions and oxides of d0 transition metals. In: Acta Crystallographica Section B . tape 32 , 1976, pp. 1334-1337 , doi : 10.1107 / S056774087600530X .
↑ V. VanRheenen, DY Cha, WM Hartley: Catalytic oxidation of osmium Tetroxide olefin: cis-1,2-Cyclohexanediol In: Organic Synthesis . 58, 1978, p. 43, doi : 10.15227 / orgsyn.058.0043 ; Coll. Vol. 6, 1988, p. 342 ( PDF ).
^ Eva-Maria Rottmayr: Light and electron microscopic examinations of the tunic of Cystodytes dellechiajei DELLA VALLE dissertation, Munich 2001, p. 28.
^ Uni Magdeburg (ed.): UMMD - intern . Faculty Council Info. No. 5 , 2011 ( uni-magdeburg.de [PDF; 763 kB ; accessed on May 21, 2016]).

[roempp-1] try on osmium tetroxide. In: Römpp Online . Georg Thieme Verlag, accessed on July 18, 2011.

[GESTIS-2] Entry on osmium (VIII) oxide in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

[Merck-SDB-3] ↑ ^a ^b ^c ^d ^e ^f data sheet osmium (VIII) oxide (PDF) from Merck , accessed on January 19, 2011.

[CLP_100.040.038-4] Entry on Osmium tetraoxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[5] Swiss Accident Insurance Fund (Suva): Limits - Current MAK and BAT values (search for 20816-12-0 or osmium (VIII) oxide ), accessed on November 2, 2015.

[6] AF Holleman , N. Wiberg : Inorganische Chemie . 103rd edition. Volume 2: Subgroup elements, lanthanoids, actinides, transactinides. Walter de Gruyter, Berlin / Boston 2016, ISBN 978-3-11-049590-4 , p. 1975 (reading sample: Part C - Subgroup elements. Google book search ).

[7] B. Krebs, K. Hasse: Refinements of the crystal structures of KTcO ₄ , KReO ₄ and OsO ₄ . Bond lengths in tetrahedral oxo-anions and oxides of d0 transition metals. In: Acta Crystallographica Section B . tape 32 , 1976, pp. 1334-1337 , doi : 10.1107 / S056774087600530X .

[8] V. VanRheenen, DY Cha, WM Hartley: Catalytic oxidation of osmium Tetroxide olefin: cis-1,2-Cyclohexanediol In: Organic Synthesis . 58, 1978, p. 43, doi : 10.15227 / orgsyn.058.0043 ; Coll. Vol. 6, 1988, p. 342 ( PDF ).

[9] Eva-Maria Rottmayr: Light and electron microscopic examinations of the tunic of Cystodytes dellechiajei DELLA VALLE dissertation, Munich 2001, p. 28.

[ummd_intern_2011_05-p-12880.pdf-10] Uni Magdeburg (ed.): UMMD - intern . Faculty Council Info. No. 5 , 2011 ( uni-magdeburg.de [PDF; 763 kB ; accessed on May 21, 2016]).