Ruthenocene is an

organoruthenium compound Organoruthenium chemistry is the chemistry of organometallic compounds containing a carbon to ruthenium chemical bond. Several organoruthenium catalysts are of commercial interest and organoruthenium compounds have been considered for cancer therapy ...

with the formula (C₅H₅)₂Ru. This pale yellow, volatile solid is classified as a

sandwich compound In organometallic chemistry, a sandwich compound is a chemical compound featuring a metal bound by hapticity, haptic, covalent bonds to two arene compound, arene (ring) ligands. The arenes have the formula , substituted derivatives (for example ...

and more specifically, as a

metallocene A metallocene is a compound typically consisting of two cyclopentadienyl anions (, abbreviated Cp) bound to a metallic element, metal center (M) in the oxidation state II, with the resulting general formula Closely related to the metallocenes are ...

Structure and bonding

Ruthenocene consists of a ruthenium ion sandwiched in between two

cyclopentadienyl Cyclopentadienyl can refer to * Cyclopentadienyl anion, or cyclopentadienide, ** Cyclopentadienyl ligand * Cyclopentadienyl radical, • * Cyclopentadienyl cation, See also * Pentadienyl {{Chemistry index ...

rings. It features ruthenium centre bound symmetrically to the planes of two cyclopentadienyl rings. It is closely related to the isoelectronic

ferrocene Ferrocene is an organometallic chemistry, organometallic compound with the formula . The molecule is a Cyclopentadienyl complex, complex consisting of two Cyclopentadienyl anion, cyclopentadienyl rings sandwiching a central iron atom. It is an o ...

. 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 The Nobel Prizes (, ) are awarded annually by the Royal Swedish Academy of Sciences, the Swedish Academy, the Karolinska Institutet, and the Norwegian Nobel Committee to individuals and organizations who make outstanding contributions in th ...

who had collaborated in assigning the structure of ferrocene only a year earlier. Originally, ruthenocene was prepared by the reaction of ruthenium trisacetylacetonate with excess of cyclopentadienylmagnesium bromide. :Ru(acac)₃ + C₅H₅MgBr → Ru(C₅H₅)₂ + 3 "acacMgBr" + "C₅H₅" Ruthenocene may also be prepared by the reaction of

sodium cyclopentadienide Sodium cyclopentadienide is an organosodium compound with the formula C5H5Na. The compound is often abbreviated as NaCp, where Cp− is the cyclopentadienide anion. Sodium cyclopentadienide is a colorless solid, although samples often are pin ...

with "ruthenium dichloride" prepared in situ by reduction of ruthenium trichloride.

Chemical properties

Ruthenocene typically oxidises via two electron change, instead of one. With

weakly coordinating anion Anions that interact weakly with cations are termed non-coordinating anions, although a more accurate term is weakly coordinating anion. Non-coordinating anions are useful in studying the reactivity of electrophilic cations. They are commonly found ...

s as electrolyte, the oxidation proceeds via a 1e step. Ruthenocene has been investigated as a photoinitiator for polymerization reactions.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.

References

{{Cyclopentadienide complexes Metallocenes Organoruthenium compounds Ruthenium(II) compounds