| Names | |
|---|---|
| Other names
Osmium oxypentafluoride
| |
| Identifiers | |
3D model (JSmol)
|
|
| |
| |
| Properties[1] | |
| OsOF5 | |
| Molar mass | 301.22 g·mol−1 |
| Appearance | emerald green solid |
| Melting point | 59.2 °C (138.6 °F; 332.3 K) |
| Boiling point | 100.6 °C (213.1 °F; 373.8 K) |
| Vapor pressure | 41.1 mmHg (304.8 K) |
| 917×10−6 cm3/mol (293.8 K) | |
| Structure[2] | |
| Orthorhombic | |
| Pnma | |
a = 9.540 Å, b = 8.669 Å, c = 5.019 Å
| |
Lattice volume (V)
|
415.1 Å3 |
Formula units (Z)
|
4 units per cell |
| Thermochemistry[1] | |
Enthalpy of fusion (ΔfH⦵fus)
|
1.62 kcal/mol |
Enthalpy of vaporization (ΔfHvap)
|
8.75 kcal/mol |
Enthalpy of sublimation (ΔfHsublim)
|
10.37 kcal/mol |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |
Osmium oxide pentafluoride is an inorganic compound with the chemical formula OsOF5. It is a paramagnetic[3] emerald green solid, notable for being a heptavalent osmium compound stable in molecular form under normal temperature and pressure.[1]
Structure
[edit]It is dimorphic, forming orthorhombic crystals and transitioning to a cubic disordered phase at 32.5 °C.[2] OsOF5, in its high temperature form, is indistinguishable crystallographically from OsF6.[2]
Preparation
[edit]Osmium oxide pentafluoride can be prepared in several ways.
From elements
[edit]It can be prepared by heating osmium metal in a stream of oxygen and fluorine (1:2 v/v). The reaction is self-sustaining after initiation by heat. The resulting product mixture is captured in a cold trap and the osmium hexafluoride byproduct is separated by difference in volatility. The yield is reported to be 50%.[1]
Fluorination of osmium dioxide
[edit]Anhydrous osmium dioxide is reacted with a slight excess of fluorine in a closed monel can. The product is separated from the osmium hexafluoride byproduct using the aforementioned technique with a yield of over 90%.[1]
OsO2 + 2.5 F2 → OsOF5 + 0.5 O2Other fluorinating agents
[edit]OsO2 is fluorinated to OsOF5 by ClF3 with quantitative yields at ambient temperature.[4]
OsO4 is fluorinated into a mixture of OsO3F2 and OsOF5 by ClF3 at ambient temperature.[4] The formation of OsOF5 corresponds to a reduction of osmium from +8 to +7.[4]
Related compounds
[edit]Other oxide fluorides of osmium are known including: OsO3F2, OsO2F3, and OsOF4.[5] There is some evidence for the existence of OsO2F2.[5]
References
[edit]- ^ a b c d e Bartlett, Neil; Jha, N. K. (1968-01-01). "The preparation and some physical properties of osmium oxide pentafluoride, OsOF5". Journal of the Chemical Society A: Inorganic, Physical, Theoretical: 536–543. doi:10.1039/J19680000536. ISSN 0022-4944.
- ^ a b c Bartlett, Neil; Trotter, James (1968-01-01). "The structure of the orthorhombic phase of osmium oxide pentafluoride, OsOF5". Journal of the Chemical Society A: Inorganic, Physical, Theoretical: 543–547. doi:10.1039/J19680000543. ISSN 0022-4944.
- ^ Holloway, John H.; Hope, Eric G.; Raynor, J. Barrie; Townson, Paul T. (1992-01-01). "Magnetic resonance studies on osmium pentafluoride oxide". Journal of the Chemical Society, Dalton Transactions (7): 1131–1134. doi:10.1039/DT9920001131. ISSN 1364-5447.
- ^ a b c Bougon, R.; Cicha, W. V.; Isabey, J. (1994-06-01). "Low-temperature fluorination of ruthenium and osmium di- and tetra-oxides". Journal of Fluorine Chemistry. 67 (3): 271–276. Bibcode:1994JFluC..67..271B. doi:10.1016/0022-1139(93)02972-H. ISSN 0022-1139.
- ^ a b Hope, Eric G.; Levason, William; Ogden, J. Steven (1988-01-01). "Spectroscopic studies on matrix isolated osmium pentafluoride oxide, osmium tetrafluoride oxide, and osmium difluoride trioxide". Journal of the Chemical Society, Dalton Transactions (1): 61–65. doi:10.1039/DT9880000061. ISSN 1364-5447.