Ruthenocene

Ruthenocene is an organoruthenium compound with the formula (C5H5)2Ru. This pale yellow, volatile solid is classified as a sandwich compound and more specifically, as a metallocene.

Ruthenocene
Names
IUPAC names
Ruthenocene
Bis(η5-cyclopentadienyl)ruthenium
Other names
ruthenium cyclopentadienyl, cp2Ru
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.013.696
EC Number
  • 215-065-2
3469
  • InChI=1S/2C5H5.Ru/c2*1-2-4-5-3-1;/h2*1-5H;/q-5;-1;
    Key: KRRYFXOQIMANBV-UHFFFAOYSA-N
  • [cH-]1cccc1.[cH-]1cccc1.[Ru+2]
Properties
C10H10Ru
Molar mass 231.26 g/mol
Appearance pale yellow powder
Density 1.86 g/cm3 (25 °C)
Melting point 195 to 200 °C (383 to 392 °F; 468 to 473 K)
Boiling point 278 °C (532 °F; 551 K)
Insoluble in water, soluble in most organic solvents
Hazards
GHS labelling:[1]
GHS07: Exclamation mark
Warning
H315, H319, H335
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
2
0
0
Related compounds
Related compounds
 cobaltocene, nickelocene, chromocene, ferrocene, osmocene, bis(benzene)chromium
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Structure and bonding

Ruthenocene consists of a ruthenium ion sandwiched in between two cyclopentadienyl rings. It features ruthenium centre bound symmetrically to the planes of two cyclopentadienyl rings. It is closely related to the isoelectronic ferrocene.

In contrast to ferrocene, wherein the cyclopentadienyl rings are in a staggered conformation, those of ruthenocene crystallise with an eclipsed conformation. This difference is due to the larger ionic radius of ruthenium, which increases the distance between the cyclopentadienyl rings, decreasing steric interactions and allowing an eclipsed conformation to prevail. In solution, these rings rotate with a very low barrier.

Preparation

Ruthenocene was first synthesized in 1952 by Geoffrey Wilkinson, a Nobel laureate who had collaborated in assigning the structure of ferrocene only a year earlier.[2] Originally, ruthenocene was prepared by the reaction of ruthenium trisacetylacetonate with excess of cyclopentadienylmagnesium bromide.[2]

Ru(acac)3 + C5H5MgBr → Ru(C5H5)2 + 3 "acacMgBr" + "C5H5"

Ruthenocene may also be prepared by the reaction of sodium cyclopentadienide with "ruthenium dichloride" prepared in situ by reduction of ruthenium trichloride.[3][4]

Chemical properties

Ruthenocene typically oxidises via two electron change, instead of one.[5] With weakly coordinating anions as electrolyte, the oxidation proceeds via a 1e step.[6]

Ruthenocene has been investigated as a photoinitiator for polymerization reactions.[7]

References
  1. "Summary of Classification and Labelling". ECHA. Retrieved 13 December 2021.
  2. Wilkinson, G. (1952). "The Preparation and Some Properties of Ruthenocene and Ruthenicinium Salts". J. Am. Chem. Soc. 74 (23): 6146–6147. doi:10.1021/ja01143a538.
  3. Bublitz, D. E; McEwen, W. E.; Kleinberg, J. (1961). "Ruthenocene". Organic Syntheses. 41: 96. doi:10.15227/orgsyn.041.0096.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. Harrypersad, Shane; Canal, John P. (2023). "The Synthesis of Ruthenocene─A Methodology Appropriate for the Inorganic Undergraduate Curriculum". Journal of Chemical Education. 100 (3): 1320–1325. Bibcode:2023JChEd.100.1320H. doi:10.1021/acs.jchemed.2c01258. S2CID 257322557.
  5. Smith, T. P; Taube, H.; Bino, A.; Cohen, S. (1984). "Reactivity of Haloruthenocene(IV) complexes". Inorg. Chem. 23 (13): 1943. doi:10.1021/ic00181a030.
  6. Geiger, W. E. and Barrière, F., "Organometallic Electrochemistry Based on Electrolytes Containing Weakly-Coordinating Fluoroarylborate Anions", Accounts of Chemical Research, 2010. doi:10.1021/ar1000023.
  7. Cynthia T. Sanderson, Bentley J. Palmer, Alan Morgan, Michael Murphy, Richard A. Dluhy, Todd Mize, I. Jonathan Amster, and Charles Kutal "Classical Metallocenes as Photoinitiators for the Anionic Polymerization of an Alkyl 2-Cyanoacrylate" Macromolecules 2002, volume 35, pp. 9648-9652.doi:10.1021/ma0212238
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