ruthenium cyclopentadienyl, cp2Ru
|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|
|S-phrases||S26, S28, S37/39, S45|
|cobaltocene, nickelocene, chromocene, ferrocene, osmocene, bis(benzene)chromium|
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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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.
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. 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 has been investigated as a photoinitiator for polymerization reactions.
- Wilkinson, G. (1952). "The Preparation and Some Properties of Ruthenocene and Ruthenicinium Salts". J. Am. Chem. Soc. 74 (23): 6146. doi:10.1021/ja01143a538..
- Bublitz, D. E; McEwen, W. E.; Kleinberg, J. (1973). "Ruthenocene". Org. Synth.; Coll. Vol. 5, p. 1001
- Smith, T. P; Taube, H.; Bino, A.; Cohen, S. (1984). "Reactivity of Haloruthenocene(IV) complexes". Inorg. Chem. 23 (13): 1943. doi:10.1021/ic00181a030.
- 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.
- 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