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Isolation and reactivity of an elusive diazoalkene


Most functional groups, especially those consisting of the abundant elements of organic matter—carbon, nitrogen and oxygen—have been extensively studied and only very few remain speculative due to their high intrinsic reactivity. In contrast to the well-explored chemistry of diazoalkanes (R2C=N2), diazoalkenes (R2C=C=N2) have been postulated in several organic transformations, but remain elusive long-sought intermediates. Here, we present a room-temperature stable diazoalkene, utilizing a dinitrogen transfer from nitrous oxide. This functional group shows dual-site nucleophilicity (C and N atoms) and features a bent C–C–N entity (124°) and a long N–N bond together with a remarkable low infrared absorption (1,944 cm–1). Substitution of N2 by an isocyanide leads to a vinylidene ketenimine. Furthermore, photochemically triggered loss of dinitrogen might proceed through a transient triplet vinylidene. We anticipate the existence of a stable diazoalkene functional group to pave an exciting avenue into the chemistry of low-valent carbon and unsaturated carbenes.

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Fig. 1: Diazoalkanes, carbenes, diazoalkenes, the corresponding vinylidenes and their appearance in organic reaction mechanisms.
Fig. 2: Synthesis and electronic structure of a stable diazoalkene.
Fig. 3: Computational analysis of 2 and diazoalkene derivatives.
Fig. 4: Reactivity of diazoalkene 2 towards a selection of electrophiles.
Fig. 5: The reaction between diazoalkene 2 and an ambiphilic isocyanide (Xyl = 2,6-dimethylphenyl) leads to a formal N2/isocyanide substitution to give vinylidene ketenimine 10.
Fig. 6: Irradiation of 2 with a 390 nm LED light source leads cleanly to C–H insertion product 12.

Data availability

All data generated and analysed during this study are included in this Article and its Supplementary Information. Crystal structure data for the solid-state structures are available free of charge from the Cambridge Crystallographic Data Centre via under reference numbers CCDC-2013705 (2), CCDC-2013706 (3), CCDC-2013708 (4), CCDC-2013709 (5), CCDC-2043960 (6), CCDC-2043961 (7), CCDC-2043962 (9), CCDC-2043959 (10), CCDC-2013707 (12), respectively. The supplementary materials for this paper include synthetic and characterization data for all reported compounds as well as computational details.


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This paper is dedicated to the memory of Manfred Regitz. This work was supported by the Fonds der Chemischen Industrie (scholarships to M.M.H. and P.W.A.), DFG (X-ray: INST 186/1324-1) and BMBF (tenure-track programme for M.M.H.). Computational resources were provided by the DFG project 405832858 and LiDO3, the high performance computing facility at TU Dortmund (DFG project 271512359). M. Alcarazo is thanked for granting access to his infrastructure at the University of Göttingen, D. Munz and F. Weinhold are acknowledged for helpful computational discussions. A. Ofial and C. Sindlinger are thanked for providing 8 and [H(Et2O)2]{Al[OC(CF3)3]4}, respectively. D.A.P. acknowledges support from the Max Planck Society. The members of the chemistry department at TU Dortmund are thanked for their support, in particular W. Hiller for the 14N and 15N NMR measurements.

Author information

Authors and Affiliations



All experiments were conducted by M.M.H. (initial discovery) and P.W.A. Crystallographic analyses of borane adducts 4 and 5 were performed by J.J.H. and C.G. measured and refined the remaining solid-state structures. DFT, NBO and NRT calculations were performed by M.M.H. and MP2, CASSCF, NEVPT2 and CCSD(T) calculations were performed by D.A.P. The project was designed and coordinated by M.M.H who also wrote the manuscript.

Corresponding author

Correspondence to M. M. Hansmann.

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The authors declare no competing interests.

Additional information

Peer review information Nature Chemistry thanks Peter Schreiner and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.

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Supplementary information

Supplementary Information

Experimental data, synthesis and characterization data, NMR spectra, X-ray crystallographic data, computational details, Supplementary figures and tables.

Supplementary Data 1

Crystallographic data for compound 2. CCDC reference 2013705.

Supplementary Data 2

Crystallographic data for compound 3. CCDC reference 2013706.

Supplementary Data 3

Crystallographic data for compound 4. CCDC reference 2013708.

Supplementary Data 4

Crystallographic data for compound 5. CCDC reference 2013709.

Supplementary Data 5

Crystallographic data for compound 6. CCDC reference 2043960.

Supplementary Data 6

Crystallographic data for compound 7. CCDC reference 2043961.

Supplementary Data 7

Crystallographic data for compound 9. CCDC reference 2043962.

Supplementary Data 8

Crystallographic data for compound 10. CCDC reference 2043959.

Supplementary Data 9

Crystallographic data for compound 12. CCDC reference 2013707.

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Antoni, P.W., Golz, C., Holstein, J.J. et al. Isolation and reactivity of an elusive diazoalkene. Nat. Chem. 13, 587–593 (2021).

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