Names | |||
---|---|---|---|
IUPAC name λ1-Azanylidene [1] | |||
Other names Aminylene Azanylene hydridonitrogen | |||
Identifiers | |||
3D model (JSmol) | |||
ChEBI | |||
ChemSpider | |||
66 | |||
PubChem CID | |||
CompTox Dashboard (EPA) | |||
| |||
| |||
Properties | |||
HN | |||
Molar mass | 15.015 g·mol−1 | ||
Conjugate acid | Nitrenium ion | ||
Structure | |||
linear | |||
Thermochemistry | |||
Heat capacity (C) | 21.19 J K−1 mol−1 | ||
Std molar entropy (S⦵298) | 181.22 kJ K−1 mol−1 | ||
Std enthalpy of formation (ΔfH⦵298) | 358.43 kJ mol−1 | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). |
Imidogen is an inorganic compound with the chemical formula NH. [2] Like other simple radicals, it is highly reactive and consequently short-lived except as a dilute gas. Its behavior depends on its spin multiplicity.
Imidogen can be generated by electrical discharge in an atmosphere of ammonia. [3]
Imidogen has a large rotational splitting and a weak spin–spin interaction, therefore it will be less likely to undergo collision-induced Zeeman transitions. [3] Ground-state imidogen can be magnetically trapped using buffer-gas loading from a molecular beam. [3]
The ground state of imidogen is a triplet, with a singlet excited state only slightly higher in energy. [4]
The first excited state (a1Δ) has a long lifetime as its relaxation to ground state (X3Σ−) is spin-forbidden. [5] Imidogen undergoes collision-induced intersystem crossing. [4]
Ignoring hydrogen atoms, imidogen is isoelectronic with carbene (CH2) and oxygen (O) atoms, and it exhibits comparable reactivity. [5] The first excited state can be detected by laser-induced fluorescence (LIF). [5] LIF methods allow for detection of depletion, production, and chemical products of NH. It reacts with nitric oxide (NO):
The former reaction is more favorable with a ΔH0 of −408±2 kJ/mol compared to a ΔH0 of −147±2 kJ/mol for the latter reaction. [6]
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.
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. [7] A temperature of about 30 K (−243 °C) favored an efficient production of CN from NH within the diffuse cloud. [8] [9] [7]
Reaction | Rate constant | Rate/[H2]2 |
---|---|---|
N + H− → NH + e− | 1×10−9 | 3.5×10−18 |
NH2 + O → NH + OH | 2.546×10−13 | 1.4×10−13 |
NH+ 2 + e− → NH + H | 3.976×10−7 | 2.19×10−21 |
NH+ 3 + e− → NH + H + H | 8.49×10−7 | 2.89×10−19 |
NH + N → N2 + H | 4.98×10−11 | 4.36×10−16 |
NH + O → OH + N | 1.16×10−11 | 1.54×10−14 |
NH + C+ → CN+ + H | 7.8×10−10 | 4.9×10−19 |
NH + H+ 3 → NH+ 2 + H2 | 1.3×10−9 | 3.18×10−19 |
NH + H+ → NH+ + H | 2.1×10−9 | 4.05×10−20 |
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. [12] The purpose of detecting NH is often to get a better estimate of the rotational constants and vibrational levels of NH. [13] 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. [14] 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. [15]
In chemistry, hydronium (hydroxonium in traditional British English) is the common name for the cation [H3O]+, also written as H3O+, the type of oxonium ion produced by protonation of water. It is often viewed as the positive ion present when an Arrhenius acid is dissolved in water, as Arrhenius acid molecules in solution give up a proton (a positive hydrogen ion, H+) to the surrounding water molecules (H2O). In fact, acids must be surrounded by more than a single water molecule in order to ionize, yielding aqueous H+ and conjugate base. Three main structures for the aqueous proton have garnered experimental support: the Eigen cation, which is a tetrahydrate, H3O+(H2O)3, the Zundel cation, which is a symmetric dihydrate, H+(H2O)2, and the Stoyanov cation, an expanded Zundel cation, which is a hexahydrate: H+(H2O)2(H2O)4. Spectroscopic evidence from well-defined IR spectra overwhelmingly supports the Stoyanov cation as the predominant form. For this reason, it has been suggested that wherever possible, the symbol H+(aq) should be used instead of the hydronium ion.
In astronomy, the interstellar medium (ISM) is the matter and radiation that exist in the space between the star systems in a galaxy. This matter includes gas in ionic, atomic, and molecular form, as well as dust and cosmic rays. It fills interstellar space and blends smoothly into the surrounding intergalactic space. The energy that occupies the same volume, in the form of electromagnetic radiation, is the interstellar radiation field. Although the density of atoms in the ISM is usually far below that in the best laboratory vacuums, the mean free path between collisions is short compared to typical interstellar lengths, so on these scales the ISM behaves as a gas (more precisely, as a plasma: it is everywhere at least slightly ionized), responding to pressure forces, and not as a collection of non-interacting particles.
The hydroxyl radical is the diatomic molecule •
OH. The hydroxyl radical is very stable as a dilute gas, but it decays very rapidly in the condensed phase. It is pervasive in some situations. Most notably the hydroxyl radicals are produced from the decomposition of hydroperoxides (ROOH) or, in atmospheric chemistry, by the reaction of excited atomic oxygen with water. It is also important in the field of radiation chemistry, since it leads to the formation of hydrogen peroxide and oxygen, which can enhance corrosion and SCC in coolant systems subjected to radioactive environments. The unpaired electron of the hydroxyl radical is officially represented by a middle dot, •, beside the O.
Vinyl alcohol, also called ethenol or ethylenol, is the simplest enol. With the formula CH2CHOH, it is a labile compound that converts to acetaldehyde immediately upon isolation near room temperature. It is not a practical precursor to any compound.
The trihydrogen cation or protonated molecular hydrogen is a cation with formula H+
3, consisting of three hydrogen nuclei (protons) sharing two electrons.
Glycolaldehyde is the organic compound with the formula HOCH2−CHO. It is the smallest possible molecule that contains both an aldehyde group and a hydroxyl group. It is a highly reactive molecule that occurs both in the biosphere and in the interstellar medium. It is normally supplied as a white solid. Although it conforms to the general formula for carbohydrates, Cn(H2O)n, it is not generally considered to be a saccharide.
The ethynyl radical (systematically named λ3-ethyne and hydridodicarbon(C—C)) is an organic compound with the chemical formula C≡CH (also written [CCH] or C
2H). It is a simple molecule that does not occur naturally on Earth but is abundant in the interstellar medium. It was first observed by electron spin resonance isolated in a solid argon matrix at liquid helium temperatures in 1963 by Cochran and coworkers at the Johns Hopkins Applied Physics Laboratory. It was first observed in the gas phase by Tucker and coworkers in November 1973 toward the Orion Nebula, using the NRAO 11-meter radio telescope. It has since been detected in a large variety of interstellar environments, including dense molecular clouds, bok globules, star forming regions, the shells around carbon-rich evolved stars, and even in other galaxies.
Hydrogen isocyanide is a chemical with the molecular formula HNC. It is a minor tautomer of hydrogen cyanide (HCN). Its importance in the field of astrochemistry is linked to its ubiquity in the interstellar medium.
Propynylidyne is a chemical compound that has been identified in interstellar space.
HCNH+, also known as protonated hydrogen cyanide, is a molecular ion of astrophysical interest. It also exists in the condensed state when formed by superacids.
Cyclopropenylidene, or c-C3H2, is a partially aromatic molecule belonging to a highly reactive class of organic molecules known as carbenes. On Earth, cyclopropenylidene is only seen in the laboratory due to its reactivity. However, cyclopropenylidene is found in significant concentrations in the interstellar medium (ISM) and on Saturn's moon Titan. Its C2v symmetric isomer, propadienylidene (CCCH2) is also found in the ISM, but with abundances about an order of magnitude lower. A third C2 symmetric isomer, propargylene (HCCCH), has not yet been detected in the ISM, most likely due to its low dipole moment.
The cyano radical (or cyanido radical) is a radical with molecular formula CN, sometimes written •CN. The cyano radical was one of the first detected molecules in the interstellar medium, in 1938. Its detection and analysis was influential in astrochemistry. The discovery was confirmed with a coudé spectrograph, which was made famous and credible due to this detection. ·CN has been observed in both diffuse clouds and dense clouds. Usually, CN is detected in regions with hydrogen cyanide, hydrogen isocyanide, and HCNH+, since it is involved in the creation and destruction of these species (see also Cyanogen).
In organic chemistry, cyanopolyynes are a family of organic compounds with the chemical formula HCnN (n = 3,5,7,…) and the structural formula H−[C≡C−]nC≡N (n = 1,2,3,…). Structurally, they are polyynes with a cyano group (−C≡N) covalently bonded to one of the terminal acetylene units (H−C≡C).
Interstellar ice consists of grains of volatiles in the ice phase that form in the interstellar medium. Ice and dust grains form the primary material out of which the Solar System was formed. Grains of ice are found in the dense regions of molecular clouds, where new stars are formed. Temperatures in these regions can be as low as 10 K, allowing molecules that collide with grains to form an icy mantle. Thereafter, atoms undergo thermal motion across the surface, eventually forming bonds with other atoms. This results in the formation of water and methanol. Indeed, the ices are dominated by water and methanol, as well as ammonia, carbon monoxide and carbon dioxide. Frozen formaldehyde and molecular hydrogen may also be present. Found in lower abundances are nitriles, ketones, esters and carbonyl sulfide. The mantles of interstellar ice grains are generally amorphous, becoming crystalline only in the presence of a star.
Phosphorus mononitride is an inorganic compound with the chemical formula PN. Containing only phosphorus and nitrogen, this material is classified as a binary nitride. From the Lewis structure perspective, it can be represented with a P-N triple bond with a lone pair on each atom. It is isoelectronic with N2, CO, P2, CS and SiO.
Takeshi Oka,, is a Japanese-American spectroscopist and astronomer specializing in the field of galactic astronomy, known as a pioneer of astrochemistry and the co-discoverer of interstellar trihydrogen cation . He is now R.A. Milliken Distinguished Service Emeritus Professor, Departments of Astronomy and Astrophysics, Chemistry; Enrico Fermi Institute; and the College of University of Chicago.
Argonium (also called the argon hydride cation, the hydridoargon(1+) ion, or protonated argon; chemical formula ArH+) is a cation combining a proton and an argon atom. It can be made in an electric discharge, and was the first noble gas molecular ion to be found in interstellar space.
A heterocumulene is a molecule or ion containing a chain of at least three double bonds between consecutive atoms, in which one or more atoms in the doubly bonded chain is a heteroatom. Such species are analogous to a cumulene in which the chain of doubly bonded atoms contains only carbon, except that at least one carbon is replaced by a heteroatom. Some authors relax the definition to include species with chains of only two double bonds between consecutive atoms, also known as heteroallenes.
Phosphorus monoxide is an unstable radical inorganic compound with molecular formula PO.