May 2023

The detection of the linear compound isocyanodiacetylene (HC4NC) was reported in 2020 by Xue and coworkers and by Cernicharo and coworkers toward TMC-1. Cernicharo and coworkers sought HC4NC toward the carbon-rich source IRC +10216 as well but did not detect it there. The first group used the 100m Green Bank Telescope for their observations, while the second group used the Yebes 40m telescope. Hyperfine lines of various rotational transistions were resolved in both sets of observations.

Isocyanopolyyne compounds with the formula H–(C≡C)2n–N≡C are evidently much rarer in space than cyanopolyyne H–(C≡C)2n–C≡N molecules. To date, the only other isocyanopolyyne compound to be detected is isocyanoacetylene (HC2NC). Both of the groups that discovered HC4NC also sought HC6NC (isocyanotriacetylene) toward TMC-1 but did not find it. In 2013, Vichietti & Haiduke published theoretical predictions of the structures and dipole moments for isocyanopolyynes as large as HC16NC.

Researcher Links
C Xue
ER Willis
RA Loomis
AM Burkhardt
CN Shingledecker
SB Charnley
MA Cordiner
S Kalenskii
MC McCarthy
E Herbst
AJ Remijan
BA McGuire

J Cernicharo
N Marcelino
M Agúndez
C Bermúdez
C Cabezas
B Tercero
JR Pardo

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