Calculation of Vertical Detachment Energies for Bromochlorobenzene Dimer Anions: Dependence of Substitution Position#

Abstract

The structure and energetics of neutral and anionic dimer configurations for three bromochlorobenzene (BCB) isomers were investigated with the quantum mechanical calculations on the level of M06‐2X/6‐311++G(d, p). The neutral dimers within 5 kcal/mol of the relative energy had the parallel‐displaced configurations for all isomers. The structures of dimer anions were obtained from these low‐energy neutral configurations, and four, two, and one configurations (relative energy < 5 kcal/mol) were found in o‐BCB, m‐BCB, and p‐BCB dimer anions, respectively. The electron was attached mainly to one of the Br atoms in o‐BCB and m‐BCB cases, and therefore the calculated vertical electron detachment energies (VDEs) were similar to the electron affinity of the atomic Br. However, the p‐BCB dimer anion had the sandwiched configuration and the negative charge was delocalized, showing the relatively small VDE value. The calculated VDE for p‐BCB agreed reasonably well with the experimental one.