Technetium(VI) fluoride

Technetium(VI) fluoride
Identifiers
CAS number 13842-93-8
Properties
Molecular formula TcF6
Molar mass 212 g/mol (98Tc)
Appearance yellow crystals[1]
Density 3,58 g/cm³ (−140 °C), solid[2]
Melting point

37.4 °C[1]
Boiling point

55.3 °C[1]
Structure
Crystal structure cubic
Hazards
EU classification not listed
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Technetium(VI) fluoride (TcF6) is a yellow inorganic compound with a low melting point. It was first identified in 1961.[3] In this compound, technetium has an oxidation state of +6, the highest oxidation state found in the technetium halides. The other such compound is technetium(VI) chloride, TcCl6. In this respect, technetium differs from rhenium which forms a heptafluoride, ReF7.[4]

Preparation

Technetium hexafluoride is prepared by heating the metal in excess of F2 at 400 °C.[3]

Tc + 3 F2 → TcF6

Properties

TcF6 is octahedral, as shown by infrared and Raman spectra.[5][6] Its low-temperature orthorhombic form converts to the higher symmetry body-centred cubic form at room temperature, like other metal hexafluorides such as RhF6 and OsF6.[7] Preliminary measurements of magnetic moment yield a value of 0.45 µB, which is lower than expected for a d1 octahedral compound.[8]

TcF6 reacts with alkaline chlorides in iodine pentafluoride (IF5) solution to form hexafluorotechnetates.[9][10]

TcF6 disproportionates on hydrolysis with aqueous NaOH to form a black precipitate of TcO2.[3]

In hydrogen fluoride solution, TcF6 reacts with hydrazinium fluoride to yield N2H6TcF6 or N2H6(TcF6)2.[11]

References

  1. ^ a b c CRC Handbook of Chemistry and Physics, 90. Ed., CRC Press, Boca Raton, Florida, 2009, ISBN 978-1-4200-9084-0, Section 4, Physical Constants of Inorganic Compounds, p. 4-93.
  2. ^ T. Drews, J. Supeł, A. Hagenbach, K. Seppelt: "Solid State Molecular Structures of Transition Metal Hexafluorides", Inorganic Chemistry, 2006, 45 (9), S. 3782–3788; doi:10.1021/ic052029f; PMID 16634614.
  3. ^ a b c Selig, H.; Chernick, C.L.; Malm, J.G. (1961). "The Preparation and Properties of TcF6". J. Inorg. & Nuclear Chem. 19 (3–4): 377–381. 
  4. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Oxford: Butterworth-Heinemann. ISBN 0080379419. 
  5. ^ Howard H. Claassen, Henry Selig, and John G. Malm (1962). "Vibrational Spectra of MoF6 and TcF6". J. Chem. Phys. 36 (11): 2888–2890. doi:10.1063/1.1732396. 
  6. ^ Howard H. Claassen, Gordon L. Goodman, John H. Holloway, and Henry Selig (1970). "Raman Spectra of MoF6, TcF6, ReF6, UF6, SF6, SeF6, and TeF6 in the Vapor State". J. Chem. Phys. 53 (1): 341–348. doi:10.1063/1.1673786. 
  7. ^ Siegel S and Northrop D A (1966). "X-Ray Diffraction Studies of Some Transition Metal Hexafluorides". Inorg. Chem. 5 (12): 2187–2188. doi:10.1021/ic50046a025. 
  8. ^ Selig, H; Cafasso, F A.; Gruen, D M.; Malm, J G. (1962). "Magnetic Susceptibility of ReF6". Journal of Chemical Physics 36 (12): 3440–3444. doi:10.1063/1.1732477. 
  9. ^ Edwards, A. J.; Hugill, D.; Peacock, R. D. (1963). "New Fluorine Compounds of Technetium". A. J. Edwards, D. Hugill & R. D. Peacock 200 (4907): 672. doi:10.1038/200672a0. 
  10. ^ D. Hugill and R. D. Peacock (1966). "Some quinquevalent fluorotechnetates". J. Chem. Soc. A: 1339–1341. doi:10.1039/J19660001339. 
  11. ^ Frlec B, Selig H, and Hyman H.H (1967). "Hydrazinium(+2) Hexafluorometalates(IV) and -(V) in the 4d and 5d Transition Series". Inorg Chem 6 (10): 1775–1783. doi:10.1021/ic50056a004.