Can Boronyl-Bearing Carbon Chains Serve as Gas-Phase Molecular Carriers of Interstellar Boron?

Boron is an exotic element in space. However, although no boron-bearing molecules have yet been identified in the interstellar medium (ISM), its unique chemical properties suggest that it could play a pivotal role in astrobiology and the origins of life. Given the isoelectronic relationship between the cyano (CN) and boronyl (BO) groups and the widespread detection of HC_nCN carbon chains in the ISM, we herein computationally investigate the potential of analogous BO-bearing chains (HC_nBO, n = 1–12) as viable gas-phase carriers of interstellar boron. Our calculations indicate that HC_nBO species exhibit lower enthalpies of formation and higher dipole moments than their CN-bearing counterparts, suggesting enhanced intrinsic stability and potential for detection via rotational spectroscopy. However, analysis of their formation and destruction pathways reveals that BO-bearing chains are susceptible to exergonic decomposition through reactions with CN radicals and H^– anions, which may significantly affect their abundances in the ISM. These findings underscore that, while HC_nBO systems emerge as theoretically attractive interstellar boron carriers, competitive decomposition and the element’s low cosmic abundance pose substantial challenges to their astrophysical detection.