Osmium dioxide

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Osmium dioxide
Osmium (IV) Oxide
Identifiers
CAS number 12036-02-1 YesY
PubChem 187574
Properties
Molecular formula OsO2
Molar mass 222.229 g/mol
Appearance black or yellow brown
Density 11.4 g/cm3
Melting point 500 °C (decomposes)
Related compounds
Related osmium oxides Osmium tetroxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Osmium dioxide is an inorganic compound with the formula OsO2. It exists as brown to black crystalline powder, but single crystals are golden and exhibit metallic conductivity. The compound crystallizes in the rutile structural motif, i.e. the connectivity is very similar to that in the mineral rutile.

Preparation[edit]

OsO2 can be obtained by the reaction of osmium with a variety of oxidizing agents, including, sodium chlorate, osmium tetroxide, and nitric oxide at about 600 °C.[1][2] Using chemical transport, one can obtain large crystals of OsO2, sized up to 7x5x3 mm3. Single crystals show metallic resistivity of ~15 μΩ cm. Typical transport agent is O
2
via the reversibly formation of volatile OsO4:[3]

OsO2 + O2 is in equilibrium with OsO4

Reactions[edit]

OsO2 does not dissolve in water but is attacked by dilute hydrochloric acid.[4][5] The crystals have rutile structure.[6] Unlike osmium tetroxide, OsO2 is not toxic.[7]

References[edit]

  1. ^ A. F. Holleman and E. Wiberg (2001). Inorganic chemistry. Academic Press. p. 1465. ISBN 0-12-352651-5. 
  2. ^ Thiele G., Woditsch P. (1969). "Neutronenbeugungsuntersuchungen am Osmium(IV)-oxid". Journal of the Less Common Metals 17 (4): 459. doi:10.1016/0022-5088(69)90074-5. 
  3. ^ D. B. Rogers, S. R. Butler, R. D. Shannon “Single Crystals of Transition-Metal Dioxides” Inorganic Syntheses, 1972, volume XIV, p. 135-145 doi:10.1002/9780470132449.ch27
  4. ^ J. E. Greedan, D. B. Willson, T. E. Haas (1968). "Metallic nature of osmium dioxide". Inorg. Chem. 7 (11): 2461–2463. doi:10.1021/ic50069a059. 
  5. ^ Yen, P (2004). "Growth and characterization of OsO
    2
    single crystals". Journal of Crystal Growth 262 (1-4): 271. doi:10.1016/j.jcrysgro.2003.10.021.
     
  6. ^ Boman C.E.; Danielsen, Jacob; Haaland, Arne; Jerslev, Bodil; Schäffer, Claus Erik; Sunde, Erling; Sørensen, Nils Andreas (1970). "Precision Determination of the Crystal Structure of Osmium Dioxide". Acta Chemica Scandinavica 24: 123–128. doi:10.3891/acta.chem.scand.24-0123. 
  7. ^ Smith, I.C., B.L. Carson, and T.L. Ferguson (1974). "Osmium: An appraisal of environmental exposure.". Env Health Perspect (Brogan &#38) 8: 201–213. doi:10.2307/3428200. JSTOR 3428200. PMC 1474945. PMID 4470919.