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 therap ...

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 haptic, covalent bonds to two arene (ring) ligands. The arenes have the formula , substituted derivatives (for example ) and heterocyclic deriv ...

and more specifically, as a

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

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 Sir Geoffrey Wilkinson FRS (14 July 1921 – 26 September 1996) was a Nobel laureate English chemist who pioneered inorganic chemistry and homogeneous transition metal catalysis. Education and early life Wilkinson was born at Springside, Todm ...

, a Nobel laureate 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 + 3 C₅H₅MgBr → Ru(C₅H₅)₂ + 3 "acacMgBr" + "C₅H₅" Ruthenocene may also be prepared by the reaction of sodium cyclopentadienide with "ruthenium dichloride" (prepared from ruthenium metal and

ruthenium trichloride Ruthenium(III) chloride is the chemical compound with the formula RuCl3. "Ruthenium(III) chloride" more commonly refers to the hydrate RuCl3·''x''H2O. Both the anhydrous and hydrated species are dark brown or black solids. The hydrate, with a va ...

''in situ'').

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

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