Abstract

Cyclic oligomers comprising strongly interacting redox-active monomer units represent an unknown, yet highly desirable class of nanoscale materials. Here we describe the synthesis and properties of the first family of molecules belonging to this compound category—differently sized rings comprising only 1,1′-disubstituted ferrocene units (cyclo[n], n = 5–7, 9). Due to the close proximity and connectivity of centres (covalent Cp–Cp linkages; Cp = cyclopentadienyl) solution voltammograms exhibit well-resolved, separated 1e waves. Theoretical interrogations into correlations based on ring size and charge state are facilitated using values of the equilibrium potentials of these transitions, as well as their relative spacing. As the interaction free energies between the redox centres scale linearly with overall ring charge and in conjunction with fast intramolecular electron transfer (107 s−1), these molecules can be considered as uniformly charged nanorings (diameter 1–2 nm).

  • Compound

    biferrocene

  • Compound

    ferrocenyl thiophene-2-carboxylate

  • Compound

    1,1'-biferrocenylene

  • Compound

    cyclo(1,1'-quinqueferrocene)

  • Compound

    cyclo(1,1'-sexiferrocene)

  • Compound

    cyclo(1,1'-septiferrocene)

  • Compound

    cyclo(1,1'-noviferrocene)

  • Compound

    1,1'-diiodoferrocene

  • Compound

    1,1'''-diiodobiferrocene

  • Compound

    1,1'''''-diiodoterferrocene

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

References

  1. 1.

    Molecule with a ring to it. Nature Chem. 7, 6–7 (2015).

  2. 2.

    & Supramolecular Chemistry 2nd edn (Wiley-Blackwell, 2009).

  3. 3.

    et al. Seven doubly bridged ferrocene units in a cycle. Angew. Chem. Int. Ed. Engl. 36, 387–389 (1997).

  4. 4.

    et al. Redox-active metallomacrocycles and cyclic metallopolymers: photocontrolled ring-opening oligomerization and polymerization of silicon-bridged [1]ferrocenophanes using substitutionally-labile Lewis bases as initiators. J. Am. Chem. Soc. 131, 14958–14968 (2009).

  5. 5.

    , , & Construction of multiferrocenyl metallacycles and metallacages via coordination-driven self-assembly: from structure to functions. Chem. Soc. Rev. 44, 2148–2167 (2015).

  6. 6.

    et al. Solvent- and light-controlled unidirectional transit of a nonsymmetric molecular axle through a nonsymmetric molecular wheel. Chem. Eur. J. 18, 16203–16213 (2012).

  7. 7.

    , & Nanoparticle characterization based on STM and STS. Chem. Soc. Rev. 44, 970–987 (2015).

  8. 8.

    , , & Industrial applications of nanoparticles. Chem. Soc. Rev. 44, 5793–5805 (2015).

  9. 9.

    Electrochemical tunnelling sensors and their potential applications. Nature Commun. 3, 829 (2012).

  10. 10.

    , & Intrinsic multistate switching of gold clusters through electrochemical gating. J. Am. Chem. Soc. 129, 9162–9167 (2007).

  11. 11.

    & A new type of organo-iron compound. Nature 168, 1039–1040 (1951).

  12. 12.

    , & Dicyclopentadienyliron. J. Chem. Soc. 632–635 (1952).

  13. 13.

    , & The aromatic reactivity of ferrocene, ruthenocene and osmocene. J. Am. Chem. Soc. 82, 76–82 (1960).

  14. 14.

    Metallocenes: Introduction to Sandwich Complexes (Wiley-Blackwell, 1997).

  15. 15.

    The [1,1]ferrocenophane system. J. Am. Chem. Soc. 88, 855–856 (1966).

  16. 16.

    , & [1n]ferrocenophanes. J. Am. Chem. Soc. 91, 2804–2805 (1969).

  17. 17.

    & A synthesis of the cyclic ferrocene tetramer [1]4ferrocenophane. Chem. Lett. 23, 67–68 (1994).

  18. 18.

    & Preparation of biferrocenyl by the Ullmann reaction. Dokl. Akad. Nauk 130, 1093–1094 (1960).

  19. 19.

    , & Formation of ferrocene oligomers from mixed Ullmann reactions of halogenoferrocenes. J. Chem. Soc. D 502–503 (1970).

  20. 20.

    & Formation of 1,1′-oligomeric ferrocenes from mixed Ullmann reactions of haloferrocenes. J. Org. Chem. 37, 729–732 (1972).

  21. 21.

    & Synthesis of ferrocenylruthenocene. Transition Metal Chem. 6, 260–263 (1981).

  22. 22.

    & Facile purification of iodoferrocene. Organometallics 30, 3908–3910 (2011).

  23. 23.

    & Formation of 1,2-oligomeric ferrocenes from Ullmann reactions of iodoferrocenes. J. Org. Chem. 141, 195–204 (1977).

  24. 24.

    & The formation of 1,1′-oligomeric ferrocenes from chloromercuriferrocene and bis(chloromercuri)ferrocene. Bull. Chem. Soc. Jpn 48, 1955–1956 (1975).

  25. 25.

    , , & Structures of lithium ferrocenylenecuprates and their oxidative coupling reactions. Organometallics 28, 4632–4635 (2009).

  26. 26.

    , , & Redox properties of hepta(1,1′-dihexylferrocenylene). Synth. Met. 84, 935–936 (1997).

  27. 27.

    & Oligonuclear ruthenocene complexes. J. Am. Chem. Soc. 45, 2032–2033 (1980).

  28. 28.

    , & Synthesis and characterization of hetero-oligometallocenes containing ruthenocene and osmocene. Z. Naturforsch. B 45, 781–784 (1990).

  29. 29.

    et al. Synthesis and preparative HPLC-separation of heteronuclear oligometallocenes. Isolation of cations of rhodocenylferrocene, 1,1′-dirhodocenylferrocene, and 1-cobaltocenyl-,1′-rhodocenylferrocene. Chromatographia 30, 543–545 (1990).

  30. 30.

    , , & Ferrocene-substituted nickelocenes via ferrocenylcyclopentadienides. Synlett 905–907 (1991).

  31. 31.

    & 1,1′-Biferrocenylenes—the more redox stable ferrocenes! New derivatives, corrected NMR assignments, redox behavior, and spectroelectrochemistry. Organometallics 31, 1870–1878 (2012).

  32. 32.

    et al. Bis(fulvalene)diiron, its mono- and dications. Intramolecular exchange interactions in a rigid system. J. Am. Chem. Soc. 98, 3181–3187 (1976).

  33. 33.

    et al. Synthesis and structure of ferrocenylphosphinic acids. J. Org. Chem. 766, 40–48 (2014).

  34. 34.

    , , , & Crystal structure of cyclic tris(ferrocene-1,1′-diyl). Acta Crystallogr. E 70, m318–m319 (2014).

  35. 35.

    et al. Synthesis of the prototypical cyclic metallocene triad: mixed-valence properties of [(FeCp)3(trindenyl)] isomers. Angew. Chem. Int. Ed. 47, 5331–5334 (2008).

  36. 36.

    & The trindene trianion. J. Am. Chem. Soc. 102, 1058–1063 (1980).

  37. 37.

    , & Ambient temperature, Ullmann-like reductive coupling of aryl, heteroaryl, and alkenyl halides. J. Org. Chem. 62, 2312–2313 (1997).

  38. 38.

    , , & A versatile copper-induced synthesis of fluorinated oligo(para-phenylenes). Tetrahedron 54, 14609–14616 (1998).

  39. 39.

    et al. New bi(tetrathiafulvalenyl) derivatives and their radical cations: synthetic and X-ray structural studies. J. Mater. Chem. 10, 1273–1279 (2000).

  40. 40.

    , & The pyrrole approach toward the synthesis of fully functionalized cup-shaped molecules. Org. Lett. 7, 1003–1006 (2005).

  41. 41.

    , , & Benzocyclotrimers: from the Mills−Nixon effect to gas hosting. Acc. Chem. Res. 44, 416–423 (2011).

  42. 42.

    , , & Oxidative purification of halogenated ferrocenes. Dalton Trans. 42, 2813–2816 (2013).

  43. 43.

    & Use of weakly coordinating anions to develop an integrated approach to the tuning of ΔE1/2 values by medium effects. J. Am. Chem. Soc. 128, 3980–3989 (2006).

  44. 44.

    , & Improved electrochemistry of multi-ferrocenyl compounds: investigation of biferrocene, terferrocene, bis(fulvalene)diiron and diferrocenylethane in dichloromethane using [NBu4][B(C6F5)4] as supporting electrolyte. J. Org. Chem. 637–639, 823–826 (2001).

  45. 45.

    & Electrochemical Methods 2nd edn (Wiley, 2004).

  46. 46.

    & Mixed-valence molecules: electronic delocalization and stabilization. Coord. Chem. Rev. 60, 107–129 (1984).

  47. 47.

    , , & Reversible voltammetric response for a molecule containing four non-equivalent redox sites with application to cytochrome c3 of Desulfovibrio vulgaris, strain Miyazaki. J. Electroanal. Chem. Interfacial Electrochem. 108, 107–115 (1980).

  48. 48.

    & Solvent effect on intramolecular electron transfer rates of mixed-valence biferrocene monocation derivatives. J. Phys. Chem. A 110, 7019–7027 (2006).

  49. 49.

    et al. Oxidation-state and electron-transfer properties of mixed-valence 1,1′-polyferrocene ions. Inorg. Chem. 14, 506–511 (1975).

  50. 50.

    & Physics for Engineers and Scientists 3rd edn (W.W. Norton & Company, 2007).

Download references

Acknowledgements

M.S.I., T.A. and N.J.L. acknowledge the Leverhulme Trust (RPG 2012-754) for funding. The authors are grateful to the referees for useful comments and suggestions concerning the extent of charge delocalization in these materials.

Author information

Affiliations

  1. Department of Chemistry, Imperial College London, London SW7 2AZ, UK

    • Michael S. Inkpen
    • , Andrew J. P. White
    • , Tim Albrecht
    •  & Nicholas J. Long
  2. Fachbereich Chemie, Universität Konstanz, Universitätsstraße 10, D-78457 Konstanz, Germany

    • Stefan Scheerer
    • , Michael Linseis
    •  & Rainer F. Winter

Authors

  1. Search for Michael S. Inkpen in:

  2. Search for Stefan Scheerer in:

  3. Search for Michael Linseis in:

  4. Search for Andrew J. P. White in:

  5. Search for Rainer F. Winter in:

  6. Search for Tim Albrecht in:

  7. Search for Nicholas J. Long in:

Contributions

M.S.I., T.A. and N.J.L. conceived the work and designed the experiments. M.S.I. synthesized the materials and performed the solution electrochemical measurements. A.J.P.W. performed the X-ray crystallographic experiments. S.S., M.L. and R.F.W. performed the UV/vis/NIR spectroscopy experiments. All authors contributed to writing the paper.

Competing interests

The authors declare no competing financial interests.

Corresponding authors

Correspondence to Tim Albrecht or Nicholas J. Long.

Supplementary information

PDF files

  1. 1.

    Supplementary information

    Supplementary information

Crystallographic information files

  1. 1.

    Supplementary information

    Crystallographic data for compound cyclo[6]-benzene

  2. 2.

    Supplementary information

    Crystallographic data for compound cyclo[6]-toluene

About this article

Publication history

Received

Accepted

Published

DOI

https://doi.org/10.1038/nchem.2553

Further reading