The cyanobutadiynyl radical (C₅N) was discovered in 1998 by Guélin et al., who observed it toward IRC+10216, a circumstellar disk around the star CW Leonis where many molecules (50+) have been detected to date. The observations were made with the 30m telescope at Pico Veleta and the 100m telescope at Effeslberg. No confirming detection has been reported to date.

The C₅N radical can be formed by removing the H atom from another observed carbon chain astromolecule, cyanodiacetylene. It's anion, C₅N^–, has also been detected.