In
organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...
, 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 (H
2N
+=N
–, also called 1,1-diimide) with general formula R
1R
2N
+=N
–. The functional group has two major resonance forms, a diazen-2-ium-1-ide form, and an aminonitrene form:
![Isodiazene](https://upload.wikimedia.org/wikipedia/commons/2/28/Isodiazene.png)
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 the ...
with
ketones and aldehydes, the reactivity of this exotic functional group is very different. They are generally prepared by oxidation of the hydrazine (R
2N–NH
2), reduction of the 1,1-diazene oxide (R
2N–N=O), 1,1-elimination of MX from R
2N–NMX (M = Na, K; X = SO
2Ar), or treatment of secondary amines with
Angeli's salt
Angeli's salt, sodium trioxodinitrate, is the inorganic compound with the formula Na2 2O3 It contains nitrogen in an unusual reduced state. It is a colorless, water-soluble solid, a salt. In research, this salt is used as a source of the metas ...
, Na
2N
2O
3, 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 N
2 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 Co ...
that is consistent with the
conservation of orbital symmetry
Conservation is the preservation or efficient use of resources, or the conservation of various quantities under physical laws.
Conservation may also refer to:
Environment and natural resources
* Nature conservation, the protection and manageme ...
.
![Retro4plus1](https://upload.wikimedia.org/wikipedia/commons/6/60/Retro4plus1.png)
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.
![Retro221](https://upload.wikimedia.org/wikipedia/commons/2/27/Retro221.png)
Due to the facile elimination of N
2, 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., R
1= R
2 = ''t-''Bu, stable at –127 °C, decomposes at –90 °C; R
1—R
2 = C(CH
3)
2CH
2CH
2CH
2(CH
3)
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
Diimide, also called diazene or diimine, is a compound having the formula (NH)2. It exists as two geometric isomers, ''E'' (''trans'') and ''Z'' (''cis''). The term diazene is more common for organic derivatives of diimide. Thus, azobenzene is ...
*
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 atoms h ...
*
Nitrene
In chemistry, a nitrene or imene () is the nitrogen analogue of a carbene. The nitrogen atom is uncharged and univalent, so it has only 6 electrons in its valence level—two covalent bonded and four non-bonded electrons. It is therefore consid ...
References
{{reflist
Functional groups
Reactive intermediates