Aromatic Carboxylate Superhalogens and Multiply Charged Anions

摘要

Ab initio calculations employing electron propagator theory and many-body perturbation theory show that the benzoate anion is a superhalide with an electron detachment energy in excess of 4.4 eV. Final states associated with vertical electron detachment energies of benzoate anion are reordered by correlation effects, and the holes associated with the lowest neutral states thereby have O-centered σ character instead of ring-centered π character. Geometry optimizations on the dianions produced by attaching two carboxylate groups to the benzene ring arrive at planar structures for the para and meta isomers, but in the ortho isomer, a C_2 structure with twisted OCO groups is found. The most stable isomer is para, and the least stable is ortho. The lowest vertical detachment energies are at least 1.4 eV for the para and meta isomers, but the estimate for the ortho isomer is 0.8 eV. Corresponding Dyson orbitals exhibit ring-centered π character. Attempts to find bound trianions with three carboxylate groups failed. In fluorinated compounds, the carboxylate groups rotate so that they are perpendicular to the ring planes. These compounds possess higher electron binding energies. The associated Dyson orbitals are delocalized over the ring. F, and carboxylate regions, and antibonding phase relationships are obtained between ring π and substituent lobes.