First detection in space of the high-energy isomer of cyanomethanimine: H2CNCN

Abstract

We report the first detection in the interstellar medium of $N$-cyanomethanimine (H${}_2$CNCN), the stable dimer of HCN of highest energy, and the most complex organic molecule identified in space containing the prebiotically relevant NCN backbone. We have identified a plethora of $a$-type rotational transitions with 3 $\le J_{\text{up}}\le$ 11 and $K_{\text{a}}\le$ 2 that belong to this species towards the Galactic Center G+0.693-0.027 molecular cloud, the only interstellar source showing the three cyanomethanimine isomers (including the $Z$- and $E$- isomers of $C$-cyanomethanimine, HNCHCN). We have derived a total column density for H${}_2$CNCN of (2.9$\pm$0.1)$\times$10${}^{12}$ cm${}^{-2}$, which translates into a total molecular abundance with respect to H${}_2$ of (2.1$\pm$0.3)$\times$10${}^{-11}$. We have also revisited the previous detection of $E$- and $Z$-HNCHCN, and found a total $C/N$-cyanomethanimine abundance ratio of 31.8$\pm$1.8 and a $Z/E$-HNCHCN ratio of 4.5$\pm$0.2. While the latter can be explained on the basis of thermodynamic equilibrium, chemical kinetics are more likely responsible for the observed $C/N$-cyanomethanimine abundance ratio, where the gas-phase reaction between methanimine (CH${}_2$NH) and the cyanogen radical (CN) arises as the primary formation route.

22 pages, 8 figures, 3 tables, 2 appendix - Accepted for publication in The Astrophysical Journal

References in corpus (36)

• An Ice Age JWST inventory of dense molecular cloud ices
• The largest oxigen bearing organic molecule repository
• Tracing shocks and photodissociation in the Galactic center region
• Yebes 40 m radio telescope and the broad band NANOCOSMOS receivers at 7 mm and 3 mm for line surveys
• Discovery in space of ethanolamine, the simplest phospholipid head group
• Detection of E-cyanomethanimine towards Sagittarius B2(N) in the Green Bank Telescope PRIMOS Survey
• Thiols in the ISM: first detection of HC(O)SH and confirmation of C${}_2$H${}_5$SH
• ALMA and ROSINA detections of phosphorus-bearing molecules: the interstellar thread between star-forming regions and comets
• Prebiotic precursors of the primordial RNA world in space: Detection of NH${}_2$OH
• Cloud-cloud collision as drivers of the chemical complexity in Galactic Centre molecular clouds
• Phosphorus-bearing molecules in the Galactic Center
• First detection of the pre-biotic molecule glycolonitrile (HOCH2CN) in the interstellar medium
• Probing the chemical complexity of amines in the ISM: detection of vinylamine (C${}_2$H${}_3$NH${}_2$) and tentative detection of ethylamine (C${}_2$H${}_5$NH${}_2$)
• Propargylimine in the laboratory and in space: millimetre-wave spectroscopy and first detection in the ISM
• Precursors of fatty alcohols in the ISM: Discovery of n-propanol
• Investigating the Minimum Energy Principle in Searches for New Molecular Species - the Case of H${}_2$C${}_3$O Isomers
• Discovery of the elusive carbonic acid (HOCOOH) in space
• First detection of C${}_2$H${}_5$NCO in the ISM and search of other isocyanates towards the G+0.693-0.027 molecular cloud
• The GUAPOS project: G31.41+0.31 Unbiased ALMA sPectral Observational Survey -- I. Isomers of C${}_2$H${}_4$O${}_2$
• The Case of H${}_2$C${}_3$O Isomers, Revisited: Solving the Mystery of the Missing Propadienone
• Detection of the cyanomidyl radical (HNCN): a new interstellar species with the NCN backbone
• Isomers in Interstellar Environments (I): The Case of Z- and E-Cyanomethanimine
• The trans/cis ratio of formic, HCOOH, and thioformic, HC(O)SH, acids in the Interstellar Medium
• The origin of the E/Z isomer ratio of imines in the interstellar medium
• On the chemical ladder of esters. Detection and formation of ethyl formate in the W51 e2 hot molecular core
• Amides inventory towards the G+0.693-0.027 molecular cloud
• Laboratory measurements and astronomical search for cyanomethanimine
• Mapping Observations of complex organic molecules around Sagittarius B2 with ARO 12m telescope
• Interstellar detection of the simplest aminocarbyne, H2NC: an ignored but abundant molecule
• Diastereoselective Formation of trans-HC(O)SH Through Hydrogenation of OCS on Interstellar Dust Grains
• Deuterium fractionation as a multi-phase component tracer in the Galactic Centre
• The first detection of SiC${}_2$ in the interstellar medium
• Discovery of CH3CHCO in TMC-1 with the QUIJOTE line survey
• Millimetre and submillimetre spectroscopy of isobutene and its detection in the molecular cloud G+0.693
• The chemistry of H2NC in the interstellar medium and the role of the C + NH3 reaction
• H2CN/H2NC abundance ratio: a new potential temperature tracer for the interstellar medium

Cited by in corpus (8)

• On the abiotic origin of dimethyl sulfide: discovery of DMS in the Interstellar Medium
• Conformational isomerism of methyl formate: new detections of the higher-energy trans conformer and theoretical insights
• The GUAPOS project. VI: the chemical inventory of shocked gas
• A detection of sulfur-bearing cyclic hydrocarbons in space
• Piecing together formic acid isomerism in dark clouds. Detection of cis-formic acid in TMC-1 and astrochemical modeling
• Expanding the C${}_3$H${}_6$O${}_2$ Isomeric Interstellar Inventory: Discovery of Lactaldehyde and Methoxyacetaldehyde in G+0.693-0.027
• Synthesis and Spectroscopic Characterization of Interstellar Candidate Ethynyl Thiocyanate: HCCSCN
• Rotational Spectra and Search for Aromatic Imines: 9-Iminofluorene and Benzophenone imine