Maleonitrile and Malononitrile Formation in the Interstellar Medium: Gas-Phase Radical Routes to Nitrogen-Rich Dinitriles

The identification of complex organic molecules (COMs) in cold dark clouds like Taurus Molecular Cloud 1 (TMC-1) has heightened interest in comprehending their chemical origins under astrochemical conditions. Notable among these is dinitrile substances such as malononitrile CH2(CN)2 and maleonitrile (Z)-NC-CH=CH-CN, which are important for their possible contributions to prebiotic chemistry and molecular diversity in the interstellar medium (ISM). This work examines the possible single-step formation processes of malononitrile and maleonitrile in the gas phase at the ωB97XD/aug-cc-pVTZ level, which accurately accounts for dispersion interactions essential for weakly bound interstellar systems. Energetic and thermodynamic factors suggest that both molecules can be generated via barrierless recombination pathways involving CN, CH2CN, and CHCN species. Spectroscopic parameters, including dipole moments and vibrational modes were calculated to assist current astronomical detection initiatives. The results enhance the comprehension of nitrogen-heavy COMs in the ISM and provides important perspectives on the chemical evolution routes that might connect interstellar organic chemistry to the beginnings of life.