Imidogen is an

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemi ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

NH. Like other simple

radicals Radical may refer to: Politics and ideology Politics *Radical politics, the political intent of fundamental societal change *Radicalism (historical), the Radical Movement that began in late 18th century Britain and spread to continental Europe and ...

, it is highly reactive and consequently short-lived except as a dilute gas. Its behavior depends on its spin multiplicity.

Production and properties

Imidogen can be generated by electrical discharge in an atmosphere of

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogeno ...

. Imidogen has a large rotational splitting and a weak spin–spin interaction, therefore it will be less likely to undergo collision-induced Zeeman transitions. Ground-state imidogen can be magnetically trapped using

buffer-gas loading A buffer gas is an inert or nonflammable gas. In the Earth's atmosphere, nitrogen acts as a buffer gas. A buffer gas adds pressure to a system and controls the speed of combustion with any oxygen present. Any inert gas such as helium, neon, or ar ...

from a molecular beam. The ground state of imidogen is a

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, with a singlet excited state only slightly higher in energy. The first excited state (a¹Δ) has a long lifetime as its relaxation to ground state (X³Σ⁻) is spin-forbidden. Imidogen undergoes collision-induced intersystem crossing.

Reactivity

Ignoring hydrogen atoms, imidogen is isoelectronic with carbene (CH₂) and oxygen (O) atoms, and it exhibits comparable reactivity. The first excited state can be detected by laser-induced fluorescence (LIF). LIF methods allow for detection of depletion, production, and chemical products of NH. It reacts with nitric oxide (NO): :NH + NO → N₂ + OH :NH + NO → N₂O + H The former reaction is more favorable with a Δ''H''⁰ of compared to a Δ''H''⁰ of for the latter reaction.

Nomenclature

The trivial name ''nitrene'' is the preferred IUPAC name. The systematic names, ''λ¹-azane'' and ''hydridonitrogen'', valid IUPAC names, are constructed according to the substitutive and additive nomenclatures, respectively. In appropriate contexts, imidogen can be viewed as ammonia with two hydrogen atoms removed, and as such, ''azylidene'' may be used as a context-specific systematic name, according to substitutive nomenclature. By default, this name pays no regard to the radicality of the imidogen molecule. Although, in even more specific context, it can also name the non-radical state, whereas the diradical state is named ''azanediyl''.

Astrochemistry

Interstellar NH was identified in the diffuse clouds toward ζ Persei and HD 27778 from high-resolution high- signal-to-noise spectra of the NH A³Π→X³Σ (0,0) absorption band near 3358 Å. A temperature of about favored an efficient production of CN from NH within the diffuse cloud.

Reactions relevant to astrochemistry

: Within diffuse clouds H⁻ + N → NH + e⁻ is a major formation mechanism. Near chemical equilibrium important NH formation mechanisms are recombinations of and ions with electrons. Depending on the radiation field in the diffuse cloud, NH₂ can also contribute. NH is destroyed in diffuse clouds by photodissociation and photoionization. In dense clouds NH is destroyed by reactions with atomic oxygen and nitrogen. O⁺ and N⁺ form OH and NH in diffuse clouds. NH is involved in creating N₂, OH, H, CN⁺, CH, N, , NH⁺ for the interstellar medium. NH has been reported in the diffuse interstellar medium but not in dense molecular clouds. The purpose of detecting NH is often to get a better estimate of the rotational constants and vibrational levels of NH. It is also needed in order to confirm theoretical data which predicts N and NH abundances in stars which produce N and NH and other stars with leftover trace amounts of N and NH. Using current values for rotational constants and vibrations of NH as well as those of OH and CH permit studying the carbon, nitrogen and oxygen abundances without resorting to a full spectrum synthesis with a 3D model atmosphere.

References

External links

* Interstellar media Nitrogen hydrides {{Hydrides by group Free radicals Diatomic molecules