Decamethylferrocene Explained

Decamethylferrocene or bis(pentamethylcyclopentadienyl)iron(II) is a chemical compound with formula or . It is a sandwich compound, whose molecule has an iron(II) cation attached by coordination bonds between two pentamethylcyclopentadienyl anions . It can also be viewed as a derivative of ferrocene, with a methyl group replacing each hydrogen atom of its cyclopentadienyl rings. The name and formula are often abbreviated to DmFc,^{[1] [2]} or .^[3]

This compound is a yellow crystalline solid that is used in chemical laboratories as a weak reductant. The iron(II) core is easily oxidized to iron(III), yielding the monovalent cation decamethylferrocenium, and even to higher oxidation states.^[3]

Preparation

Decamethylferrocene is prepared in the same manner as ferrocene from pentamethylcyclopentadiene. This method can be used to produce other decamethylcyclopentadienyl sandwich compounds.^[4]

2 Li(C₅Me₅) + FeCl₂ → Fe(C₅Me₅)₂ + 2 LiCl

The product can be purified by sublimation. has staggered rings. The average distance between iron and each carbon is approximately 2.050 Å. This structure has been confirmed by X-ray crystallography.^[5]

Redox reactions

Like ferrocene, decamethylferrocene forms a stable cation because Fe(II) is easily oxidized to Fe(III). Because of the electron donating methyl groups on the groups, decamethylferrocene is more reducing than is ferrocene. In a solution of acetonitrile the reduction potential for the couple is −0.59 V compared to a reference (−0.48 V vs Fc/ in).^[6] Oxygen is reduced to hydrogen peroxide by decamethylferrocene in acidic solution.^[7]

Using powerful oxidants (e.g. or in, or in) decamethylferrocene is oxidized to a stable dication with an iron(IV) core. In the salt, the rings are parallel. In contrast, a tilt angle of 17° between the rings is observed in the crystal structure of the salt.^[3]

References

1. 2014 . Characterization of decamethylferrocene and ferrocene in ionic liquids: argon and vacuum effect on their electrochemical properties . Electrochimica Acta . 137 . 235–244 . 10.1016/j.electacta.2014.06.005 . Torriero . Angel A. J..
2. Noviandri . Indra . Brown . Kylie N. . Fleming . Douglas S. . Gulyas . Peter T. . Lay . Peter A. . Masters . Anthony F. . Phillips . Leonidas . The Decamethylferrocenium/Decamethylferrocene Redox Couple: A Superior Redox Standard to the Ferrocenium/Ferrocene Redox Couple for Studying Solvent Effects on the Thermodynamics of Electron Transfer . The Journal of Physical Chemistry B . 1 August 1999 . 103 . 32 . 6713–6722 . 10.1021/jp991381+ . 1520-6106.
3. 2016 . Isolation and structural and electronic characterization of salts of the decamethylferrocene dication . Science . 353 . 6300. 678–682 . 10.1126/science.aaf6362 . 27516596 . Malischewski . M. . Adelhardt . M. . Sutter . J. . Meyer . K. . Seppelt . K. . 2016Sci...353..678M . 43385610 .
4. King . R. B. . Bisnette . M. B. . . 10.1016/S0022-328X(00)91042-8 . Organometallic Chemistry of the Transition Metals XXI. Some π-pentamethylcyclopentadienyl Derivatives of Various Transition Metals . 1967 . 8 . 2 . 287–297.
5. . 10.1021/ja00498a017 . 1979 . 101 . 4 . 892–897. Crystal and molecular structures of decamethylmanganocene and decamethylferrocene. Static Jahn-Teller distortion in a metallocene . Freyberg . Derek P. . Robbins . John L. . Raymond . Kenneth N. . Smart . James C. .
6. Connelly . N. . Geiger . W. E. . Chemical Redox Agents for Organometallic Chemistry . . 96 . 1996 . 2 . 877–910 . 10.1021/cr940053x . 11848774.
7. Su. Bin. Hatay. Imren. Ge. Pei Yu. Mendez. Manuel. Corminboeuf. Clemence. Clémence Corminboeuf. Samec. Zdenek. Ersoz. Mustafa. Girault. Hubert H.. 2010. Oxygen and proton reduction by decamethylferrocene in non-aqueous acidic media. Chem. Commun.. 46. 17. 2918–2919. 10.1039/B926963K. 20386822.