Detection of the cyanomidyl radical (HNCN): a new interstellar species with the NCN backbone

We report here the first detection in the interstellar medium of the cyanomidyl radical (HNCN). Using the Yebes 40m and the IRAM 30m telescopes, we have targeted the doublets of the N = 2-1, 4-3, 5-4, 6-5, and 7-6 transitions of HNCN towards the molecular cloud G+0.693-0.027. We have detected three unblended lines of HNCN, these are the N = 6-5 doublet and one line of the N = 4-3 transition. Additionally, we present one line of the N = 5-4 transition partially blended with emission from other species. The local thermodynamic equilibrium best fit to the data gives a molecular abundance of (0.91 ± 0.05) × 10^-10 with respect to H₂. The relatively low abundance of this species in G+0.693-0.027 and its high reactivity suggest that HNCN is possibly produced by gas-phase chemistry. Our work shows that this highly reactive molecule is present in interstellar space, and thus it represents a plausible precursor of larger prebiotic molecules with the nitrogen-carbon-nitrogen backbone such as cyanamide (NH₂CN), carbodiimide (HNCNH), and formamidine (NH₂CHNH).