The benzene radical anion is an important reactive intermediate in organic chemistry in a process known as the Birch reduction where benzene is partially reduced by solvated electrons in liquid
ammonia. Beyond organic chemistry, it is an intriguing subject of spectroscopic and theoretical studies due to its rich structural properties and dynamic behavior. Gas-phase ab initio calculations predict the anion to be a metastable shape resonance, while experiments in the condensed phase and a stable species.
Here, we approach the system by ab initio molecular dynamics in bulk liquid ammonia and highlight the key role of solvation by demonstrating that the species exhibits stability in solution,
consistent with experimental observations. Beyond the mere existence of the radical anion species, our simulations explore its condensed-phase behavior at the molecular level, compare it to
its neutral benzene counterpart, and oer new insights into its properties. These include the previously studied dynamic Jahn Teller distortions as well as new ones, such as vibrational spectra in liquid ammonia and the structure of the solvent shell, including the structural motive of a π-hydrogen bond between ammonia molecules and the
aromatic ring.