Abstract
The reaction of the nitrogen atom (N) in its first electronically excited state (2D) with cyanoacetylene (HC3N) has been investigated under single-collision conditions by using the crossed molecular beam method with mass spectrometric detection at a collision energy of 31 kJ mol−1. With the support of electronic structure calculations, we found that this reaction proceeds via the barrierless addition of the N(2D) atom to the carbon–carbon triple bond of HC3N, followed by the formation of a cyclic intermediate adduct HC(N)CCN, which dissociates to C(N)CCN + H products or isomerises to a more stable intermediate HNCCCN by H-migration and ring-opening processes. The long-lived HNCCCN complex produces the linear 3Σg– ground state dicyanocarbene (NCCCN) radical plus atomic hydrogen through a barrierless unimolecular dissociation accompanied by a negligible competitive channel forming the NCCCN radical (1A1) with a bent C2v structure plus H. The main product of this neutral-neutral reaction is the 3NCCCN radical that could be a potential precursor to form other nitriles (C2N2, C3N) or more complex organic species in planetary atmospheres, such as that of Titan and Pluto, in cometary comas, and in UV irradiated interstellar environments.
GRAPHICAL ABSTRACT
Acknowledgments
The authors thank Isabelle Couturier-Tamburelli (Aix-Marseille Université-PIIM, Marseille, FR), Murthy Gudipati (JPL, USA) and Benjamin Fleury (JPL, USA) for kindly sharing their experience in synthesising and handling of HC3N. Y. T. acknowledges financial support from the extra-[EU ERASMUS+ program (Academic Year 2019/2020)].
Disclosure statement
No potential conflict of interest was reported by the author(s).
Correction Statement
This article has been corrected with minor changes. These changes do not impact the academic content of the article.