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Although isodiazenes are formally 
The absence of cyclobutane from the decomposition of the isodiazene derived from the saturated 5-membered azacycle is evidence against radical intermediates, and the process is also believed to be concerted and pericyclic.
Due to the facile elimination of N2, most isodiazenes can only be isolated in a matrix at cryogenic temperatures. 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.
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...
, 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
Isoelectronicity is a phenomenon observed when two or more molecules have the same structure (positions and connectivities among atoms) and the same electronic configurations, but differ by what specific elements are at certain locations in th ...
with ketones and aldehydes, the reactivity of this exotic functional group is very different. They are generally prepared by oxidation of the hydrazine (R2N–NH2), reduction of the 1,1-diazene oxide (R2N–N=O), 1,1-elimination of MX from R2N–NMX (M = Na, K; X = SO2Ar), or treatment of secondary amines with Angeli's salt, Na2N2O3, in the presence of acid. Isodiazenes participate in cycloaddition reactions with alkenes to generate ''N''-aminoaziridines. In the absence of other reactants, they undergo reactions in which N2 is eliminated to give an organic residue or residues through both concerted and nonconcerted pathways. Cyclic isodizenes in particular readily undergo cycloelimination and chelotropic elimination reactions. Some of these reactions are believed to be concerted pericyclic processes, as evidenced by stereospecificity
In chemistry, stereospecificity is the property of a reaction mechanism that leads to different stereoisomeric reaction products from different stereoisomeric reactants, or which operates on only one (or a subset) of the stereoisomers."Overlap C ...
that is consistent with the conservation of orbital symmetry.
The absence of cyclobutane from the decomposition of the isodiazene derived from the saturated 5-membered azacycle is evidence against radical intermediates, and the process is also believed to be concerted and pericyclic.
Due to the facile elimination of N2, most isodiazenes can only be isolated in a matrix at cryogenic temperatures. 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.
See also
* Diazene *Ylide
An ylide () or ylid () is a neutral dipolar molecule containing a formally negatively charged atom (usually a carbanion) directly attached to a heteroatom with a formal positive charge (usually nitrogen, phosphorus or sulfur), and in which both ...
* Nitrene
In chemistry, a nitrene or imene () is the nitrogen analogue of a carbene. The nitrogen atom is uncharged and valence (chemistry)#monovalent, monovalent, so it has only 6 electrons in its valence level—two covalent bonded and four non-bonded e ...
References
{{reflist Functional groups Reactive intermediates