Isodiazene

Isodiazene
Identifiers
3D model (JSmol)
  • InChI=1S/H2N2/c1-2/h1H2
    Key: CREXVNNSNOKDHW-UHFFFAOYSA-N
  • [NH2+]=[N-]
Properties
H2N2
Molar mass 30.030 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

In organic chemistry, an isodiazene, also known by the incorrectly constructed (but commonly used) name 1,1-diazene or systematic name diazanylidene, is an organic derivative of the parent isodiazene (H2N+=N–, also called 1,1-diimide) with general formula R1R2N+=N–. The functional group has two major resonance forms, a diazen-2-ium-1-ide form, and an aminonitrene form:

Although isodiazenes are formally isoelectronic with ketones and aldehydes, the reactivity of this exotic functional group is very different.

In the absence of other reactants, they facilely undergo reactions in which N2 is eliminated. Consequently, most isodiazenes can only be isolated in a matrix at cryogenic temperatures. They are generally used to "snip out" nitrogen atoms from molecules, typically leaving two radicals that then couple.

Preparation

There are multiple methods for the preparation of isodiazene intermediates:

Stable isodiazenes

A small number of highly hindered derivatives with tertiary R groups (e.g., R1= R2 = t-Bu, stable at –127 °C, decomposes at –90 °C; R1—R2 = C(CH3)2CH2CH2CH2(CH3)2C, stable up to –78 °C) are isolable by preparation and chromatography or filtration at low temperature as red solutions.

Isodiazenes have been observed to serve as ligands in transition metals complexes, including those of molybdenum and vanadium.

Atypical reactions

Elimination of N2 from cyclic isodiazenes is concerted, not radical:

If the reaction were radical, then a cyclobutane would be expected. Also, the reaction exhibits stereospecificity consistent with Woodward and Hoffman's rules:

Isodiazenes participate in cycloaddition reactions with alkenes to generate N-aminoaziridines.

See also

References

  1. ↑ IUPAC, Compendium of Chemical Terminology, 5th ed. (the "Gold Book") (2025). Online version: (2006–) "isodiazenes". doi:10.1351/goldbook.I03273
  2. 1 2 3 4 5 Kuznetsov, M A; Ioffe, B V (31 August 1989). "The present state of the chemistry of aminonitrenes and oxynitrenes". Russian Chemical Reviews. 58 (8): 732–746. Bibcode:1989RuCRv..58..732K. doi:10.1070/rc1989v058n08abeh003474. S2CID 250826036.
  3. ↑ Hanson, James Edward (21 June 2007). I. Matrix Isolation of 1,1-Diazenes. II. Distance, Temperature, and Dynamic Solvent Effects on Electron Transfer Reactions (Thesis). California Institute of Technology. pp. 2–31. doi:10.7907/1F5A-AC10.
  4. 1 2 3 4 Bi Xihe; Wei Hao; Lu Hongjian; Song Song (Dec 9, 2025) [July 9, 2025]. "Skeletal editing of cyclic scaffolds". CCS Chemistry. 8: 647–650. doi:10.31635/ccschem.025.202506288.
  5. ↑ Xu Yi-An; Xiang Shao-Hua; Che Jin-Teng; Wang Yong-Bin; Tan Bin (2024). "Skeletal editing of cyclic molecules using nitrenes". Chinese Journal of Chemistry. 42. Wiley: 2660–2661. doi:10.1002/cjoc.202400342.
  6. ↑ Carey, Francis A.; Sundberg, Richard J. (2007). Advanced Organic Chemistry. Part B: Reactions and Synthesis (5th ed.). New York, NY: Springer. ISBN 9781601195494. OCLC 223941000.
  7. ↑ Burwell, Frederick Powell (June 1970). Untitled PhD thesis on nitroso-substituted nitrogenous rings (Part I: "The synthesis and reduction of cis- and trans-1‑nitroso-2,4‑diphenyl­azetidine"; Part II: "The attempted synthesis of 1‑nitroso-2,7‑diphenyl­hexahydroazepine"). Polytechnic Institute of Brooklyn.
  8. ↑ McIntyre, Daniel K.; Dervan, Peter B. (November 1982). "1,1-Di-tert-butyldiazene". Journal of the American Chemical Society. 104 (23): 6466–6468. Bibcode:1982JAChS.104.6466M. doi:10.1021/ja00387a061.
  9. ↑ Dilworth, J.R. (January 2017). "Diazene, diazenido, isodiazene and hydrazido complexes". Coordination Chemistry Reviews. 330: 53–94. doi:10.1016/j.ccr.2016.09.006.