Biferrocene

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Biferrocene
Biferrocene.svg
Names
IUPAC name
1,1"-Biferrocene
Identifiers
3D model (JSmol)
ChemSpider
PubChem CID
  • InChI=1S/C10H8.2C5H5.2Fe/c1-2-6-9(5-1)10-7-3-4-8-10;2*1-2-4-5-3-1;;/h1-8H;2*1-5H;;/q-6;2*-1;;
    Key: CEMHVYUXQJEPPO-UHFFFAOYSA-N
  • C1=C[CH-]C=C1.[Fe+2].C2=C[C-](C=C2)[C-](C=C3)C=C3.[Fe+2].C1=C[CH-]C=C1
Properties
C20H18Fe2
Molar mass 370.054 g·mol−1
Appearancedark orange solid
Melting point 239–240 °C (462–464 °F; 512–513 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Biferrocene is the organometallic compound with the formula [(C5H5)Fe(C5H4)]2. It is the product of the formal dehydrocoupling of ferrocene, analogous the relationship between biphenyl and benzene. It is an orange, air-stable solid that is soluble in nonpolar organic solvents.

Contents

Biferrocene can be prepared by the Ullmann coupling of iodoferrocene. [1] Its one-electron oxidized derivative [(C5H5)Fe(C5H4)]2+ attracted attention as a prototypical mixed-valence compound. [2]

A related compound is biferrocenylene, [Fe(C5H4)2]2 wherein all cyclopentadienyl rings are coupled into two fulvalene ligands.

Reactions

Biferrocene can easily be converted into a mixed-valence complex, which is called biferrocenium. This [Fe(II)-Fe(III)] cation is a class II type (0.707 > α > 0) mixed-valence complex according to the Robin-Day classification. [2]

Derivatives

Aminophosphine ligands with biferroceno substituents have been prepared as catalysts for asymmetric allylic substitution [3] and asymmetric hydrogenation of alkenes. [4]

References

  1. ↑ M. D. Rausch (1961). "Ferrocene and Related Organometallic π-Complexes. IV. Some Ullmann Reactions of Haloferrocenes". J. Org. Chem. 26 (6): 1802–1805. doi:10.1021/jo01065a026.
  2. 1 2 Cowan, D. O.; LeVanda, C.; Park, J.; Kaufman, F. (1973). "Organic Solid State. VIII. Mixed-Valence Ferrocene Chemistry". Acc. Chem. Res. 6: 1–7. doi:10.1021/ar50061a001.
  3. ↑ Xiao, Li; Weissensteiner, Walter; Mereiter, Kurt; Widhalm, Michael (2002-03-08). "Novel Chiral Biferrocene Ligands for Palladium-Catalyzed Allylic Substitution Reactions" . The Journal of Organic Chemistry. 67 (7): 2206–2214. doi:10.1021/jo016249w. ISSN   0022-3263. PMID   11925230.
  4. ↑ Zirakzadeh, Afrooz; Groß, Manuela A.; Wang, Yaping; Mereiter, Kurt; Weissensteiner, Walter (2014-04-09). "Walphos versus Biferrocene-Based Walphos Analogues in the Asymmetric Hydrogenation of Alkenes and Ketones". Organometallics. 33 (8): 1945–1952. doi:10.1021/om401074a. ISSN   0276-7333. PMC   4006446 . PMID   24795493.
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