Ab initio molecular orbital study of dinitrobenzene radical anions

A theoretical study of 1,3-dinitrobenzene (DNB) radical anion, which exhibits an intramolecular electron transfer reaction in solution, is reported. The geometries of 1,3-DNB and 1,4-DNB radical anions have been optimized as isolated species to reveal their intrinsic properties by using CASSCF theory with the aug-cc-pVDZ basis set. Single-point energy calculations have been carried out at the CASPT2 and CCSD(T) levels. It is demonstrated that the 1,3-DNB radical anion is slightly more stable as an electronically localized structure in the absence of solvent, whereas the 1,4-DNB radical anion has a delocalized structure.