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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 from a molecular beam.
The first excited state (aΔ) has a long lifetime as its relaxation to ground state (XΣ) 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 ΔH of −408±2 kJ/mol compared to a ΔH of −147±2 kJ/mol for the latter reaction.
Nomenclature
The trivial namenitrene is the preferred IUPAC name. The systematic names, λ-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 AΠ→XΣ (0,0) absorption band near 3358 Å. A temperature of about 30 K (−243 °C) favored an efficient production of CN from NH within the diffuse cloud.
Reactions relevant to astrochemistry
Chemical reactions
Reaction
Rate constant
Rate/
N + H → NH + e
1×10
3.5×10
NH2 + O → NH + OH
2.546×10
1.4×10
NH 2 + e → NH + H
3.976×10
2.19×10
NH 3 + e → NH + H + H
8.49×10
2.89×10
NH + N → N2 + H
4.98×10
4.36×10
NH + O → OH + N
1.16×10
1.54×10
NH + C → CN + H
7.8×10
4.9×10
NH + H 3 → NH 2 + H2
1.3×10
3.18×10
NH + H → NH + H
2.1×10
4.05×10
Within diffuse clouds H + N → NH + e is a major formation mechanism. Near chemical equilibrium important NH formation mechanisms are recombinations of NH 2 and NH 3 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 2, 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.
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