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An isolable germylyne radical with a one-coordinate germanium atom



Carbynes (R–\({{{\dot{\mathrm C:}}}}\)), species that bear a monovalent carbon atom with three non-bonding valence electrons, are important intermediates and potentially useful in organic synthetic chemistry. However, free species of the type R–\({{{\dot{\mathrm E:}}}}\) of any group 14 element (E) have eluded isolation in the condensed phase due to their high reactivity. Here we report the isolation, characterization and reactivity of a crystalline germylyne radical by using a sterically hindered hydrindacene ligand. The germylyne radical bears an essentially one-coordinate germanium atom as shown by single-crystal X-ray diffraction analysis. Electron paramagnetic resonance spectroscopic studies and theoretical calculations show that the germylyne radical features a doublet ground state, and the three non-bonding valence electrons at the germanium atom contribute to the lone pair of electrons as the highest occupied molecular orbital-3 and one unpaired electron as the singly occupied molecular orbital.

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Fig. 1: Carbynes and their heavier analogues.
Fig. 2: Synthesis of the germylyne radical 4.
Fig. 3: Characterization of 4.
Fig. 4: Theoretical calculations of 4 at the BP86+(D3BJ)/def2-TZVPP// BP86+(D3BJ)/def2-SVP level.
Fig. 5: Reactivity studies of the germylyne radical 4.

Data availability

Crystallographic data for the structures reported in this article have been deposited at the Cambridge Crystallographic Data Centre, under deposition numbers CCDC 2125007 (1), 2125008 (3), 2125009 (4), 2125010 (5), 2166315 (6) and 2125011 (7). Copies of the data can be obtained free of charge via All other relevant data generated and analysed during this study, which include experimental, spectroscopic, crystallographic and computational data, are included in this article and its supplementary information. Source data are provided with this paper.


  1. Moss, R. A., Platz, M. S. & Jones, M. Jr Reactive Intermediate Chemistry (Wiley, 2004).

  2. Swings, P. & Rosenfeld, L. Considerations regarding interstellar molecules. Astrophys. J. 86, 483–486 (1937).

    Article  CAS  Google Scholar 

  3. Thap Do, M., Gunning, H. E. & Strausz, O. P. Formation and reactions of monovalent carbon intermediates. I. Photolysis of diethyl mercuribisdiazoacetate. J. Am. Chem. Soc. 89, 6785–6787 (1967).

    Article  Google Scholar 

  4. Strausz, O. P., Thap, D. M. & Font, J. Formation and reactions of monovalent carbon intermediates. II. Further studies on the decomposition of diethyl mercurybisdiazoacetate. J. Am. Chem. Soc. 90, 1930–1931 (1968).

    Article  CAS  Google Scholar 

  5. Patrick, T. B. & Kovitch, G. H. Photolysis of diethyl mercurybisdiazoacetate and ethyl diazoacetate in chloroalkanes. J. Org. Chem. 40, 1527–1528 (1975).

    Article  CAS  Google Scholar 

  6. Patrick, T. B. & Wu, T.-T. Photodecomposition of diethyl mercurybis(diazoacetate) in several heterocyclic systems. J. Org. Chem. 43, 1506–1509 (1978).

    Article  CAS  Google Scholar 

  7. Bino, A., Ardon, M. & Shirman, E. Formation of a carbon–carbon triple bond by coupling reactions in aqueous solution. Science 308, 234 (2005).

    Article  CAS  PubMed  Google Scholar 

  8. Bogoslavsky, B. et al. Do carbyne radicals really exist in aqueous solution? Angew. Chem. Int. Ed. 51, 90–94 (2012).

    Article  CAS  Google Scholar 

  9. Wang, Z., Herraiz, A. G., del Hoyo, A. M. & Suero, M. G. Generating carbyne equivalents with photoredox catalysis. Nature 554, 86–91 (2018).

    Article  CAS  PubMed  Google Scholar 

  10. Lein, M., Krapp, A. & Frenking, G. Why do the heavy-atom analogues of acetylene E2H2 (E = Si−Pb) exhibit unusual structures? J. Am. Chem. Soc. 127, 6290–6299 (2005).

    Article  CAS  PubMed  Google Scholar 

  11. Li, H., Feng, H., Sun, W., Xie, Y. & Schaefer, H. F. Diatomic silylynes, germylynes, stannylynes, and plumbylynes: structures, dipole moments, dissociation energies, and quartet-doublet gaps of EH and EX (E = Si, Ge, Sn, Pb; X = F, Cl, Br, I). Inorg. Chem. 52, 6849–6859 (2013).

    Article  CAS  PubMed  Google Scholar 

  12. Zhao, L., Pan, S., Holzmann, N., Schwerdtfeger, P. & Frenking, G. Chemical bonding and bonding models of main-group compounds. Chem. Rev. 119, 8781–8845 (2019).

    Article  CAS  PubMed  Google Scholar 

  13. Hildenbrand, D. L., Lau, K. H. & Sanjurjo, A. Experimental thermochemistry of the SiCl and SiBr radicals; enthalpies of formation of species in the Si−Cl and Si−Br systems. J. Phys. Chem. A 107, 5448–5451 (2003).

    Article  CAS  Google Scholar 

  14. Hudson, A., Lappert, M. F. & Lednor, P. W. Subvalent group 4B metal alkyls and amides. Part 4. An electron spin resonance study of some long-lived photochemically synthesised trisubstituted silyl, germyl, and stannyl radicals. J. Chem. Soc. Dalton Trans. 1976, 2369–2375 (1976).

    Article  Google Scholar 

  15. Tao, L., Lai, T. Y., Power, P. P. & Britt, R. D. Germanium hydride radical trapped during the photolysis/thermolysis of diarylgermylene. Inorg. Chem. 58, 15034–15038 (2019).

    Article  CAS  PubMed  Google Scholar 

  16. Hashimoto, H. & Tobita, H. Recent advances in the chemistry of transition metal–silicon/germanium triple-bonded complexes. Coord. Chem. Rev. 355, 362–379 (2018).

    Article  CAS  Google Scholar 

  17. Li, J., Schenk, C., Goedecke, C., Frenking, G. & Jones, C. A digermyne with a Ge–Ge single bond that activates dihydrogen in the solid state. J. Am. Chem. Soc. 133, 18622–18625 (2011).

    Article  CAS  PubMed  Google Scholar 

  18. Sasamori, T. et al. Synthesis and reactions of a stable 1,2-diaryl-1,2-dibromodisilene: a precursor for substituted disilenes and a 1,2-diaryldisilyne. J. Am. Chem. Soc. 130, 13856–13857 (2008).

    Article  CAS  PubMed  Google Scholar 

  19. Sekiguchi, A., Kinjo, R. & Ichinohe, M. A stable compound containing a silicon–silicon triple bond. Science 305, 1755–1757 (2004).

    Article  CAS  PubMed  Google Scholar 

  20. Stender, M., Phillips, A. D., Wright, R. J. & Power, P. P. Synthesis and characterization of a digermanium analogue of an alkyne. Angew. Chem. Int. Ed. 41, 1785–1787 (2002).

    Article  CAS  Google Scholar 

  21. Peng, Y., Ellis, B. D., Wang, X., Fettinger, J. C. & Power, P. P. Reversible reactions of ethylene with distannynes under ambient conditions. Science 325, 1668–1670 (2009).

    Article  CAS  PubMed  Google Scholar 

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

    Article  CAS  PubMed  Google Scholar 

  23. Lai, T. Y., Tao, L., Britt, R. D. & Power, P. P. Reversible Sn–Sn triple bond dissociation in a distannyne: support for charge-shift bonding character. J. Am. Chem. Soc. 141, 12527–12530 (2019).

    Article  CAS  PubMed  Google Scholar 

  24. Hinz, A. & Müller, M. P. Attempted reduction of a carbazolyl-diiodoalane. Chem. Commun. 57, 12532–12535 (2021).

    Article  CAS  Google Scholar 

  25. Queen, J. D., Lehmann, A., Fettinger, J. C., Tuononen, H. M. & Power, P. P. The monomeric alanediyl:Al \({\rm{Ar}}^{^i{\rm{Pr}}_8}\) (\({\rm{Ar}}^{^i{\rm{Pr}}_8}\) = C6H-2,6-(C6H2-2,4,6-iPr3)-2-3,5-iPr2): an organoaluminum(I) compound with a one-coordinate aluminum atom. J. Am. Chem. Soc. 142, 20554–20559 (2020).

    Article  CAS  PubMed  Google Scholar 

  26. Zhang, X. & Liu, L. L. A free aluminylene with diverse σ-donating and doubly σ/π-accepting ligand features for transition metals. Angew. Chem. Int. Ed. 60, 27062–27069 (2021).

    Article  CAS  Google Scholar 

  27. Hinz, A. Pseudo-one-coordinate tetrylenium salts bearing a bulky carbazolyl substituent. Chem. Eur. J. 25, 3267–3271 (2019).

    CAS  PubMed  Google Scholar 

  28. Hinz, A. A mono-substituted silicon(II) cation: a crystalline ‘supersilylene’. Angew. Chem. Int. Ed. 59, 19065–19069 (2020).

    Article  CAS  Google Scholar 

  29. Li, J. et al. Weak arene stabilization of bulky amido-germanium(II) and tin(II) monocations. Angew. Chem. Int. Ed. 51, 9557–9561 (2012).

    Article  CAS  Google Scholar 

  30. Dielmann, F. et al. A crystalline singlet phosphinonitrene: a nitrogen atom-transfer agent. Science 337, 1526–1528 (2012).

    Article  CAS  PubMed  Google Scholar 

  31. Liu, L., Ruiz, D. A., Munz, D. & Bertrand, G. A singlet phosphinidene stable at room temperature. Chem 1, 147–153 (2016).

    Article  CAS  Google Scholar 

  32. Gendy, C., Mikko Rautiainen, J., Mailman, A. & Tuononen, H. M. Low-valent germanylidene anions: efficient single-site nucleophiles for activation of small molecules. Chem. Eur. J. 27, 14405–14409 (2021).

    Article  CAS  PubMed  Google Scholar 

  33. Li, Y. et al. Trapping a silicon(I) radical with carbenes: A cationic CAAC–silicon(I) radical and an NHC–parent-silyliumylidene cation. Angew. Chem. Int. Ed. 56, 7573–7578 (2017).

    Article  CAS  Google Scholar 

  34. Siddiqui, M. M. et al. Isolation of transient acyclic germanium(I) radicals stabilized by cyclic alkyl(amino) carbenes. J. Am. Chem. Soc. 141, 1908–1912 (2019).

    Article  CAS  PubMed  Google Scholar 

  35. Woodul, W. D. et al. A neutral, monomeric germanium(I) radical. J. Am. Chem. Soc. 133, 10074–10077 (2011).

    Article  CAS  PubMed  Google Scholar 

  36. Matsuo, T. et al. Synthesis and structures of a series of bulky ‘Rind-Br’ based on a rigid fused-ring s-hydrindacene skeleton. Bull. Chem. Soc. Jpn 84, 1178–1191 (2011).

    Article  CAS  Google Scholar 

  37. He, Y., Dai, C., Wang, D., Zhu, J. & Tan, G. Phosphine-stabilized germylidenylpnictinidenes as synthetic equivalents of heavier nitrile and isocyanide in cycloaddition reactions with alkynes. J. Am. Chem. Soc. 144, 5126–5135 (2022).

    Article  CAS  PubMed  Google Scholar 

  38. Bresien, J. et al. Increasing steric demand through flexible bulk—primary phosphanes with 2,6-bis(benzhydryl)phenyl backbones. Dalton Trans. 48, 3786–3794 (2019).

    Article  CAS  PubMed  Google Scholar 

  39. Hadlington, T. J., Schwarze, B., Izgorodina, E. I. & Jones, C. Two-coordinate hydrido-germylenes. Chem. Commun. 51, 6854–6857 (2015).

    Article  CAS  Google Scholar 

  40. Reinhold, C. R. W., Schmidtmann, M., Tumanskii, B. & Müller, T. Radicals and anions of siloles and germoles. Chem. Eur. J. 27, 12063–12068 (2021).

    Article  CAS  PubMed  Google Scholar 

  41. Drost, C., Griebel, J., Kirmse, R., Lönnecke, P. & Reinhold, J. A stable and crystalline triarylgermyl radical: structure and EPR spectra. Angew. Chem. Int. Ed. 48, 1962–1965 (2009).

    Article  CAS  Google Scholar 

  42. Lee, V. Y. et al. From a (silatrigerma)cyclobutenylium ion to a (silatrigerma)cyclobutenyl radical and back. J. Am. Chem. Soc. 142, 16455–16460 (2020).

    Article  CAS  PubMed  Google Scholar 

  43. Lu, X. et al. A two-coordinate neutral germylene supported by a β-diketiminate ligand in the radical state. Organometallics 36, 2706–2709 (2017).

    Article  CAS  Google Scholar 

  44. Olmstead, M. M., Pu, L., Simons, R. S. & Power, P. P. Reduction of Ge(Cl)C6H3-Mes2-2,6 to give the cyclotrigermenyl radical (GeC6H3-Mes2-2,6)3•. and the trigermenyl anion salt K(GeC6H3-Mes2-2,6)3. Chem. Commun. 1997, 1595–1596 (1997).

    Article  Google Scholar 

  45. Sekiguchi, A., Fukawa, T., Nakamoto, M., Lee, V. Y. & Ichinohe, M. Isolable silyl and germyl radicals lacking conjugation with π-bonds: synthesis, characterization, and reactivity. J. Am. Chem. Soc. 124, 9865–9869 (2002).

    Article  CAS  PubMed  Google Scholar 

  46. Sharma, M. K. et al. Isolation of a Ge(I) diradicaloid and dihydrogen splitting. J. Am. Chem. Soc. 143, 121–125 (2021).

    Article  CAS  PubMed  Google Scholar 

  47. Zhao, L., Hermann, M., Schwarz, W. H. E. & Frenking, G. The Lewis electron-pair bonding model: modern energy decomposition analysis. Nat. Rev. Chem. 3, 48–63 (2019).

    Article  CAS  Google Scholar 

  48. Zhao, L., von Hopffgarten, M., Andrada, D. M. & Frenking, G. Energy decomposition analysis. WIREs Comput. Mol. Sci. 8, e1345 (2018).

    Article  Google Scholar 

  49. Lemierre, V. et al. Flash vacuum thermolysis of 3,4-dimethyl-1-germacyclopent-3-enes: UV photoelectron spectroscopic characterization of GeH2 and GeMe2. Appl. Organomet. Chem. 18, 676–683 (2004).

    Article  CAS  Google Scholar 

  50. Ottmers, D. M. & Rase, H. F. Potassium graphites prepared by mixed-reaction technique. Carbon 4, 125–127 (1966).

    Article  CAS  Google Scholar 

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This work was supported by the National Natural Science Foundation of China (grant nos. 22071164 and 21973044), Suzhou Science & Technology NOVA Program (grant no. ZXL2022445), the ‘Jiangsu Specially-Appointed Professor Plan’ and the Natural Science Foundation of Jiangsu Province (grant no. BK20211587). L.Z. and G.F. also acknowledge financial support from Nanjing Tech University (grant nos. 39837123 and 9837132) and the High Performance Center of Nanjing Tech University for supporting the computational resources. G.F. is grateful to the Deutsche Forschungsgemeinschaft for financial support. We thank S. Yao (Technical University Berlin) for proofreading the manuscript.

Author information

Authors and Affiliations



G.T. conceived and instructed the experimental work. D.W. conducted the experiments with input from Y.C., S.W. and Y.H. Y.H. and D.W. collected the single-crystal X-ray diffraction data. X.C. analysed and interpreted the EPR data. L.Z. and G.F. supervised the theoretical research. C.Z. carried out the theoretical calculations. G.T., L.Z. and X.W. wrote the original draft, which was reviewed and edited with input from all authors.

Corresponding authors

Correspondence to Lili Zhao, Gernot Frenking or Gengwen Tan.

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The authors declare no competing interests.

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Peer review information

Nature Chemistry thanks Robin Fulton, Thomas Mueller and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Supplementary Figs. 1–29, discussion and Tables 1–4.

Supplementary Data 1

Crystallographic data for compound 1; CCDC 2125007.

Supplementary Data 2

Crystallographic data for compound 3; CCDC 2125008.

Supplementary Data 3

Crystallographic data for compound 4; CCDC 2125009.

Supplementary Data 4

Crystallographic data for compound 5; CCDC 2125010.

Supplementary Data 5

Crystallographic data for compound 6; CCDC 2166315.

Supplementary Data 6

Crystallographic data for compound 7; CCDC 2125011.

Supplementary Data 7

Computational data; coordinates for compound 4.

Supplementary Data 8

EPR data for Supplementary Fig. 3a,b.

Source data

Source Data Fig. 3b

EPR data for Fig. 3b.

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Wang, D., Zhai, C., Chen, Y. et al. An isolable germylyne radical with a one-coordinate germanium atom. Nat. Chem. (2022).

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