Cyano radical

Cyano radical

Names
Preferred IUPAC name Cyano radical
Systematic IUPAC name Isocyano
Other names Cyanyl Nitrile
Identifiers
CAS Number	2074-87-5 Y
Beilstein Reference	1697323
ChEBI	CHEBI:29306 Y
ChemSpider	4514240 Y
Gmelin Reference	88
Jmol 3D model	Interactive image
PubChem	5359238
InChI InChI=1S/CN/c1-2 Y Key: JEVCWSUVFOYBFI-UHFFFAOYSA-N Y
SMILES [C]#N
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

The cyano radical is a radical with molecular formula ·CN. The cyano radical was one of the first detected molecules in the interstellar medium and has helped the field of astrochemistry a great deal. The first discovery was performed with a coude 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 HCHN⁺ since it is also used In the creation and destruction of these molecules.

Physical Properties

The cyano radical is best depicted as a combination of two resonance structures: the structure with the unpaired electron on the carbon is the minor contributor, while the structure with the unpaired electron on the nitrogen (the isocyano radical) is the major contributor. The charge separation in the isocyano radical is similar to that of carbon monoxide.

·CN has a dipole moment of 1.45 Debye and a ²Σ ground electronic state. The selection rules are:

$N + S = J$

$J + I = F$

Where N is the angular momentum, S is the electric spin, and I = 1 is the nuclear spin of ¹⁴N.

Formation and destruction of ·CN

Formation

• Dissociative Recombination In Diffuse Clouds: HCN⁺ + e⁻ → ·CN + ·H
• Photo-Dissociation In Dense Clouds: HCN + hv → ·CN + ·H

Destruction

H₃⁺ + ·CN → HCN⁺ + H₂

Detections of ·CN

·CN was first detected In 1941 by A. McKellar In the interstellar medium.

The coude spectrograph and a 100-inch (2.5 m) telescope were used to observe ·CN's interstellar lines and ultraviolet spectra. Use of the spectrograph proved McKellar's findings to be correct and also made the spectrograph famous. In 1970, ·CN's first rotational transition from J=0 to J=1 was detected In the Orion Nebula and W₅₁. The first detection of ·CN in extragalactic sources were seen toward Sculptor Galaxy (NGC 253), IC 342, and M82 In 1988. These emission lines seen were from N=1 to N=0 and N=2 to N=1. In 1991, the ·CN vibration-rotational bands were observed in a king furnace at the National Solar Observatory using a McMath Fourier-Transform spectrometer. The observed 2 to 0 lines show an extreme hyperfine structure. In 1995, the rotational absorption spectrum of ·CN in the ground state was observed in the 1 THz region, and most of the lines were measured in the range of 560 to 1020 GHz. Four new rotational transitions were measured; N=8 to N=8, J=15/2 to J=17/2 and J=17/2 to J=19/2; N=7 to N=8, J=15/2 to J=17/2 and J=13/2 to J=15/2.