A stable heavier group 14 analogue of vinylidene

Subjects

Abstract

Vinylidene (H2C=C) is a member of the family of compounds of composition CH (and isomeric with ethyne, HC≡CH), but it has been observed only transiently—with a lifetime in the region of 0.1 ns. Indeed, no simple (non-base-stabilized) compounds of the type R2E=E have been characterized structurally for any of the group 14 elements. Here we show that by employing the bulky and strongly electron-donating boryl ligand (HCDippN)2B (Dipp, 2,6-iPr2C6H3), a simple monomeric digermavinylidene compound, (boryl)2GeGe, can be synthesized and is stable at room temperature. Both its formation via the two-electron chemical oxidation of the symmetrical Ge0 compound K2[(boryl)GeGe(boryl)] and its subsequent reaction chemistry (for example, with H2), are consistent with a high substituent lability and the accessibility of both 1,1- and 1,2-substitution patterns. Structural and computational studies of [(HCDippN)2B]2GeGe reveal a weak Ge–Ge double bond—the π component of which contributes to the highest occupied molecular orbital (HOMO)—with a Ge-centred lone pair as the HOMO–1.

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Figure 1: Isomeric forms of E2H2.
Figure 2: Synthesis of digermavinylidene 5 and the related digermanium systems 2 and 3.
Figure 3: Molecular structures as determined by X-ray crystallography.
Figure 4: Electron-density surfaces and energies for key molecular orbitals of 5.
Figure 5: Uptake of dihydrogen by digermavinylidene 5.

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Acknowledgements

This work was supported by the Marie Curie Intra-European Fellowships programme of the European Union (PIEF-GA-2013-622806) and the Engineering and Physical Sciences Research Council (EP/L025000/1).

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Authors

Contributions

A.R. synthesized and characterized the compounds. A.R. and J.C. collected the single-crystal X-ray crystallographic data and solved the crystal structures. A.R. and H.N. carried out the DFT calculations. S.A. generated and managed the project and wrote the manuscript. All the authors discussed the results and commented on the manuscript.

Corresponding author

Correspondence to Simon Aldridge.

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The authors declare no competing financial interests.

Supplementary information

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Supplementary information (PDF 1046 kb)

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Crystallographic data for compound 1 (CIF 34 kb)

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Structure factors file for compound 1 (FCF 547 kb)

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Crystallographic data for compound 2 (CIF 8685 kb)

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Crystallographic data for compound 3.1/2(C7H8) (CIF 1658 kb)

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Crystallographic data for compound 4 (CIF 1630 kb)

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Crystallographic data for compound 5 (CIF 1137 kb)

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Crystallographic data for compound 6 (CIF 643 kb)

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Rit, A., Campos, J., Niu, H. et al. A stable heavier group 14 analogue of vinylidene. Nature Chem 8, 1022–1026 (2016). https://doi.org/10.1038/nchem.2597

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