Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Equilibrium between a cyclotrisilene and an isolable base adduct of a disilenyl silylene


In organic chemistry, compounds with adjacent alkene and carbene functionalities (vinyl carbenes) are studied widely as fleeting intermediates and in the coordination sphere of transition metals. Stable derivatives of vinyl carbenes remain elusive, including the corresponding heavier group 14 homologues. Here we report the isolation and full characterization of a base-stabilized silicon version of a vinyl carbene that features a silicon–silicon double bond as well as a silylene functionality, coordinated by an N-heterocyclic carbene (NHC). In solution, the intensely green disilenyl silylene adduct exists in equilibrium with the corresponding silicon analogue of a cyclopropene and free NHC, which was quantified by nuclear magnetic resonance spectroscopy and ultraviolet–visible spectroscopy. The reversibility of this process raises exciting possibilities for the preparation of extended conjugated π systems of silicon.

This is a preview of subscription content, access via your institution

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: Selected examples of low-valent silicon species stabilized by N-heterocyclic carbenes as reported in the literature.
Figure 2: Equilibrium of cyclotrisilene 1 and N-heterocyclic carbene 2 with NHC-coordinated disilenyl silylene 3 and proposed cyclic intermediate 4.
Figure 3: Molecular structure of 3·C6H12 in the solid state. Hydrogen atoms and co-crystallized cyclohexane are omitted for clarity (thermal ellipsoids at 50%).
Figure 4: UV-vis spectra of 1 (red line) in hexane with increasing concentrations of NHC 2 (other lines).
Figure 5: Frontier molecular orbitals of NHC-coordinated disilenyl silylene 3 at 0.04 atomic units.


  1. Trinquier, G. & Malrieu, J. Nonclassical distortions at multiple bonds. J. Am. Chem. Soc. 109, 5303–5315 (1987).

    CAS  Article  Google Scholar 

  2. Filtvedt, W. O., Holt, A., Ramachandran, P. A. & Melaaen, M. C. Chemical vapor deposition of silicon from silane: review of growth mechanisms and modeling/scaleup of fluidized bed reactors. Sol. Energ. Mat. Sol. Cells 107, 188–200 (2012).

    CAS  Article  Google Scholar 

  3. Kira, M. & Iwamoto, T. Progress in the chemistry of stable disilenes. Adv. Organomet. Chem. 54, 73–148 (2006).

    CAS  Article  Google Scholar 

  4. Mizuhata, Y., Sasamori, T. & Tokitoh, N. Stable heavier carbene analogues. Chem. Rev. 109, 3479–3511 (2009).

    CAS  Article  Google Scholar 

  5. West, R. Inorganic chemistry: two-armed silicon. Nature 485 49–50 (2012).

    CAS  Article  Google Scholar 

  6. Lavallo, V., Canac, Y., Donnadieu, B., Schoeller, W. W. & Bertrand, G. Cyclopropenylidenes: from interstellar space to an isolated derivative in the laboratory. Science 312, 722–724 (2006).

    CAS  Article  Google Scholar 

  7. Hutton, R., Manion, M. & Roth, H. Geometric isomers of vinylmethylene. J. Am. Chem. Soc. 96, 4680–4682 (1974).

    CAS  Article  Google Scholar 

  8. Weber, W. & de Meijere, A. Tetrachlorovinylcarbene from tetrachlorocyclopropene; facile synthesis of vinylcyclopropanes. Angew. Chem. Int. Ed. Engl. 19, 138–140 (1980).

    Article  Google Scholar 

  9. Diver, S. T. Ruthenium vinyl carbene intermediates in enyne metathesis. Coord. Chem. Rev. 251, 671–701 (2007).

    CAS  Article  Google Scholar 

  10. Moss, R. A. et al. Kinetic studies of the cyclization of singlet vinylchlorocarbenes. Org. Lett. 7, 4645–4648 (2005).

    CAS  Article  Google Scholar 

  11. Kosa, M., Karni, M. & Apeloig, Y. Trisilaallene and the relative stability of Si3H4 isomers. J. Chem. Theory. Comput. 2, 956–964 (2006).

    CAS  Article  Google Scholar 

  12. Asay, M., Jones, C. & Driess, M. N-Heterocyclic carbene analogues with low-valent group 13 and group 14 elements: syntheses, structures, and reactivities of a new generation of multitalented ligands. Chem. Rev. 111, 354–96 (2011).

    CAS  Article  Google Scholar 

  13. Yao, S., Xiong, Y. & Driess, M. Zwitterionic and donor-stabilized N-heterocyclic silylenes (NHSis) for metal-free activation of small molecules. Organometallics 30, 1748–1767 (2011).

    CAS  Article  Google Scholar 

  14. Wang, Y. et al. A stable silicon(0) compound with a Si=Si double bond. Science 321, 1069–1071 (2008).

    CAS  Article  Google Scholar 

  15. Ghadwal, R. S., Roesky, H. W., Merkel, S., Henn, J. & Stalke, D. Lewis base stabilized dichlorosilylene. Angew. Chem. Int. Ed. 48, 5683–5686 (2009).

    CAS  Article  Google Scholar 

  16. Filippou, A. C., Chernov, O. & Schnakenburg, G. SiBr2(Idipp): a stable N-heterocyclic carbene adduct of dibromosilylene. Angew. Chem. Int. Ed. 48, 5687–5690 (2009).

    CAS  Article  Google Scholar 

  17. Filippou, A. C., Chernov, O., Blom, B., Stumpf, K. W. & Schnakenburg, G. Stable N-heterocyclic carbene adducts of arylchlorosilylenes and their germanium homologues. Chem. Eur. J. 16, 2866–2872 (2010).

    CAS  Article  Google Scholar 

  18. Baird, M. S. Thermally induced cyclopropene–carbene rearrangements: an overview. Chem. Rev. 103, 1271–1294 (2003).

    CAS  Article  Google Scholar 

  19. Baird, M. S., Al Dulayymi, J. R., Rzepa, H. S. & Thoss, V. An unusual example of stereoelectronic control in the ring opening of 3,3-disubstituted 1,2-dichlorocyclopropenes. Chem. Commun. 1323–1325 (1992).

  20. Shimoda, T. et al. Solution-processed silicon films and transistors. Nature 440, 783–786 (2006).

    CAS  Article  Google Scholar 

  21. Bejan, I. & Scheschkewitz, D. Two Si–Si double bonds connected by a phenylene bridge. Angew. Chem. Int. Ed. 46, 5783–5786 (2007).

    CAS  Article  Google Scholar 

  22. Abersfelder, K. & Scheschkewitz, D. Syntheses of trisila analogues of allyl chlorides and their transformations to chlorocyclotrisilanes, cyclotrisilanides, and a trisilaindane. J. Am. Chem. Soc. 130, 4114–4121 (2008).

    CAS  Article  Google Scholar 

  23. Yamaguchi, T., Sekiguchi, A. & Driess, M. An N-heterocyclic carbene–disilyne complex and its reactivity toward ZnCl2 . J. Am. Chem. Soc. 132, 14061–14063 (2010).

    CAS  Article  Google Scholar 

  24. Leszczyńska, K. et al. Reversible base coordination to a disilene. Angew. Chem. Int. Ed. 51, 6785–6788 (2012).

    Article  Google Scholar 

  25. Power, P. P. Main-group elements as transition metals. Nature 463, 171–177 (2010).

    CAS  Article  Google Scholar 

  26. Fokin, A. et al. Stable alkanes containing very long carbon–carbon bonds. J. Am. Chem. Soc. 134, 13641–13650 (2012).

    CAS  Article  Google Scholar 

  27. Kuhn, N. & Kratz, T. Synthesis of imidazol-2-ylidenes by reduction of imidazole-2 (3H)-thiones. Synthesis 561–561 (1993).

Download references


We thank the Engineering and Physical Sciences Research Council (EP/H048804/1), the Alfried Krupp Foundation, the European Commission for a Marie-Curie Fellowship (M.J.C.) and P. Jutzi and K. Leszczyńska (Bielefeld) for discussions and suggestions.

Author information

Authors and Affiliations



M.J.C. conceived and performed experiments, and co-wrote the manuscript. V.H. determined the solid-state structure of 3. H.S.R. performed the theoretical calculations, co-wrote the manuscript and designed the theoretical part of the study. D.S. designed and coordinated the study and co-wrote the manuscript.

Corresponding authors

Correspondence to Henry S. Rzepa or David Scheschkewitz.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary information

Supplementary information (PDF 1116 kb)

Supplementary information

Crystallographic data for compound 3 (CIF 49 kb)

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Cowley, M., Huch, V., Rzepa, H. et al. Equilibrium between a cyclotrisilene and an isolable base adduct of a disilenyl silylene. Nature Chem 5, 876–879 (2013).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

Further reading


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing