Decamethylferrocene or bis(pentamethylcyclopentadienyl)iron(II) is a chemical compound with formula Fe(C5(CH3)5)2 or C20H30Fe. It is a sandwich compound, whose molecule has an iron(II) cation Fe2+ attached by coordination bonds between two pentamethylcyclopentadienyl anions (Cp*−, (CH3)5C−5). 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,[3] Me10Fc [4] or FeCp*2.[5]
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| Names | |
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| Preferred IUPAC name
Decamethylferrocene | |
Other names
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3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.116.086 |
PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| C20H30Fe | |
| Molar mass | 326.305 g·mol−1 |
| Appearance | Yellow crystalline solid[1] |
| Melting point | 291 to 295 °C (556 to 563 °F; 564 to 568 K)[1] |
| 413 K, 5.3 Pa[2] | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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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.[5]
Preparation
editDecamethylferrocene is prepared in the same manner as ferrocene from pentamethylcyclopentadiene. This method can be used to produce other decamethylcyclopentadienyl sandwich compounds.[1]
- 2 Li(C5Me5) + FeCl2 → Fe(C5Me5)2 + 2 LiCl
The product can be purified by sublimation. FeCp*2 has staggered Cp* rings. The average distance between iron and each carbon is approximately 2.050 Å. This structure has been confirmed by X-ray crystallography.[6]
Redox reactions
editLike ferrocene, decamethylferrocene forms a stable cation because Fe(II) is easily oxidized to Fe(III). Because of the electron donating methyl groups on the Cp* groups, decamethylferrocene is more reducing than is ferrocene. In a solution of acetonitrile the reduction potential for the [FeCp*2]+/0 couple is −0.59 V compared to a [FeCp2]0/+ reference (−0.48 V vs Fc/Fc+ in CH2Cl2).[2] Oxygen is reduced to hydrogen peroxide by decamethylferrocene in acidic solution.[7]
Using powerful oxidants (e.g. SbF5 or AsF5 in SO2, or XeF+/Sb2F−11 in HF/SbF5) decamethylferrocene is oxidized to a stable dication with an iron(IV) core. In the Sb2F−11 salt, the Cp* rings are parallel. In contrast, a tilt angle of 17° between the Cp* rings is observed in the crystal structure of the SbF−6 salt.[5]
References
edit- ^ a b c King, R. B.; Bisnette, M. B. (1967). "Organometallic Chemistry of the Transition Metals XXI. Some π-pentamethylcyclopentadienyl Derivatives of Various Transition Metals". J. Organomet. Chem. 8 (2): 287–297. doi:10.1016/S0022-328X(00)91042-8.
- ^ a b Connelly, N.; Geiger, W. E. (1996). "Chemical Redox Agents for Organometallic Chemistry". Chem. Rev. 96 (2): 877–910. doi:10.1021/cr940053x. PMID 11848774.
- ^ Torriero, Angel A. J. (2014). "Characterization of decamethylferrocene and ferrocene in ionic liquids: argon and vacuum effect on their electrochemical properties". Electrochimica Acta. 137: 235–244. doi:10.1016/j.electacta.2014.06.005.
- ^ Noviandri, Indra; Brown, Kylie N.; Fleming, Douglas S.; Gulyas, Peter T.; Lay, Peter A.; Masters, Anthony F.; Phillips, Leonidas (1 August 1999). "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. 103 (32): 6713–6722. doi:10.1021/jp991381+. ISSN 1520-6106.
- ^ a b c Malischewski, M.; Adelhardt, M.; Sutter, J.; Meyer, K.; Seppelt, K. (2016). "Isolation and structural and electronic characterization of salts of the decamethylferrocene dication". Science. 353 (6300): 678–682. Bibcode:2016Sci...353..678M. doi:10.1126/science.aaf6362. PMID 27516596. S2CID 43385610.
- ^ Freyberg, Derek P.; Robbins, John L.; Raymond, Kenneth N.; Smart, James C. (1979). "Crystal and molecular structures of decamethylmanganocene and decamethylferrocene. Static Jahn-Teller distortion in a metallocene". J. Am. Chem. Soc. 101 (4): 892–897. doi:10.1021/ja00498a017.
- ^ Su, Bin; Hatay, Imren; Ge, Pei Yu; Mendez, Manuel; Corminboeuf, Clemence; 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. doi:10.1039/B926963K. PMID 20386822.