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

Abstract

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 HCnCN carbon chains in the ISM, we herein computationally investigate the potential of analogous BO- bearing chains (HCnBO, n = 1−12) as viable gas-phase carriers of interstellar boron. Our calculations indicate that HCnBO 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 HCnBO systems emerge as theoretically attractive interstellar boron carriers, competitive decomposition and the element’s low cosmic abundance pose substantial challenges to their astrophysical detection.