Osmocene

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Osmocene
Names
Preferred IUPAC name
Osmocene[1]
Other names
  • Di(cyclopentadienyl)osmium
  • Bis(η5-cyclopentadienyl)osmium
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
 100.013.687 Edit this at Wikidata
  • InChI=1S/2C5H5.Os/c2*1-2-4-5-3-1;/h2*1-5H;/q2*-1;+2 ☒N
    Key: RMYKEUKAFJLONI-UHFFFAOYSA-N ☒N
  • InChI=1/2C5H5.Os/c2*1-2-4-5-3-1;/h2*1-5H;/q2*-1;+2
    Key: RMYKEUKAFJLONI-UHFFFAOYAC
  • [cH-]1cccc1.[cH-]1cccc1.[Os+2]
Properties
C10H10Os
Molar mass 320.42 g·mol−1
Appearance white solid
Melting point 234 °C
Boiling point 298 °C
Structure[2]
orthorhombic
Pnma, No. 62
D5h
Related compounds
Related compounds
 ferrocene, ruthenocene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Osmocene is an

organoosmium compound found as a white solid. It is a metallocene
with the formula Os(C5H5)2.

Synthesis

Osmocene is commercially available. It may be prepared by the reaction of osmium tetroxide with hydrobromic acid followed by zinc and cyclopentadiene.[2]

It was first synthesized by Ernst Otto Fischer and Heinrich Grumbert via the reaction of osmium(IV) chloride with excess sodium cyclopentadienide in dimethoxyethane, where osmium(II) chloride is presumed to be an intermediate formed in situ. Alternatively, cyclopentadienyl magnesium bromide could be reacted with osmium(IV) chloride, though this has worse yields.[3]

Properties

Osmocene is a white solid. The molecular structure features an osmium ion sandwiched between two cyclopentadienyl rings. It is isomorphous to the lighter homologue ruthenocene, both crystallizing in an eclipsed conformation. This is in contrast to ferrocene, which crystallizes with its rings staggered.[2]

Compared to ferrocene and ruthenocene, osmocene is less reactive towards electrophilic aromatic substitution but has the greatest tendency towards

Lewis acids.[4]

The osmocenium cation [Os(C5H5)2]+ dimerizes, forming a binuclear complex with an Os-Os bond.[5] In contrast, the decamethylosmocenium cation [Os(C5(CH3)5)2]+ is stable as the monomer.[6]

Uses

In 2009, Horst Kunkely and Arnd Vogler reported the possibility of photocatalytic water splitting with osmocene as a catalyst.[7]

References

  1. ISBN 978-0-85404-182-4
    .
  2. ^
    S2CID 96874978
    .
  3. doi:10.1002/cber.19590920948
    .
  4. doi:10.1021/ic00105a067
    .
  5. doi:10.1021/ic00255a023
    .
  6. ISBN 978-3-540-46128-9
    .
  7. PMID 19173275
    .
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