Decamethylferrocene

Decamethylferrocene
IUPAC name Bis(η5 pentamethylcyclopentadienyl)iron(II)
Other names Decamethyl-ferrocene; 1,1',2,2',3,3',4,4',5,5'-Decamethyl-ferrocene; Bis(pentamethylcyclopentadienyl)iron(II); Permethylferrocene
Identifiers
CAS number	12126-50-0
Properties
Molecular formula	C20H30Fe
Molar mass	326.3 g mol−1
Appearance	Yellow crystalline solid[1]
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Decamethylferrocene is a sandwich compound. In terms of structure and bonding it resembles ferrocene, but with a methyl group on each of the carbons of the Cp rings. It is a yellow crystalline solid that is a weak reductant.

Preparation

Decamethylferrocene 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. FeCp₂* 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.^[2]

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 Cp* groups, decamethylferrocene is more reducing than is ferrocene. In a solution of CH₂Cl₂, the reduction potential for the [FeCp₂*]^+/0 couple is -0.59 V compared to a [FeCp₂]^0/+ reference.^[3] Oxygen is reduced to hydrogen peroxide by decamethylferrocene in acidic solution.^[4]

References

1. ^ ^{a b} King, R. B., and M. B. Bisnette (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. 
2. ^ Freyberg, D. J, L. Robbins, K.N. Raymond and J.C. Smart (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. 
3. ^ Connelly, N., and W.E. Geiger (1996). "Chemical Redox Agents for Organometallic Chemistry". Chem. Rev. 96: 877–910. doi:10.1021/cr940053x. PMID 11848774. 
4. ^ Su, B.; Hatay, I.; Ge, P. Y.; Mendez, M.; Corminboeuf, C.; Samec, Z.; Ersoz, M. and Girault, H. H., "Oxygen and proton reduction by decamethylferrocene in non-aqueous acidic media", Chem. Commun., 2010, volume 46, 2918-2919. doi:10.1039/B926963K