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An isolable germylyne radical with a one-coordinate germanium atom

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Abstract

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 https://www.ccdc.cam.ac.uk/structures/. 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.

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Acknowledgements

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

Authors

Contributions

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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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). https://doi.org/10.1038/s41557-022-01081-1

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