Discovery of interstellar 3-cyano propargyl radical, CH2CCCN

Abstract

We report the first detection in interstellar space of the 3-cyano propargyl radical (CH2C3N). This species was observed in the cold dark cloud TMC-1 using the Yebes 40m telescope. A total of seven rotational transitions for both ortho- and para-CH2C3N species were observed in the 31.0-50.4 GHz range. We derive a total column density of (1.6 +/- 0.4)e11 cm-2 and an ortho/para ratio of 2.4 +/- 1.2, which implies an abundance ratio CH2C3N/CH3C3N around 0.1, in sharp contrast with the smaller analogues, in which case CH2CN/CH3CN = 3. This indicates that the chemistry of the cyanides CH2C3N and CH3C3N behaves differently to that of the smaller analogues CH2CN and CH3CN. According to our chemical model calculations, the radical CH2C3N is mostly formed through the neutral-neutral reactions C + CH2CHCN, C2 + CH3CN, and CN + CH2CCH together with the dissociative recombination of the CH3C3NH+ ion with electrons. The neutral-neutral reaction N + C4H3 could also lead to CH2C3N, although its role is highly uncertain. The identified radical CH2C3N could play a role in the synthesis of large organic N-bearing molecules, such as benzonitrile (c-C6H5CN) or nitrogen heterocycles.

Accepted for publication in A&A Letters

References in corpus (18)

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• Discovery of benzyne, o-C6H4, in TMC-1 with the QUIJOTE line survey
• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
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• Astrochemical Modeling of Propargyl Radical Chemistry in TMC-1
• New deuterated species in TMC-1: Detection of CH2DC4H with the QUIJOTE line survey
• Laboratory observation and astronomical search of 1-cyano propargyl radical, HCCCHCN
• A high-resolution spectroscopic analysis of aminoacrylonitrile and an interstellar search towards G+0.693
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• Chemical complexity in star formation induced by stellar feedback: cores shock-formed by the supernova remnant W44