A multiconfigurational study of anion-radical and dianion of 1,3-dinitrobenzene

The CASSCF method was used to reveal the structure of anion-radical (AR) and dianion (DA) of 1,3-dinitrobenzene in ground and lowest excited states. The calculations indicate the presence of two asymmetric (2A″) and one C2v symmetric (2A2) structures of AR. The asymmetric AR-2A″ structure is 4 kcal/mol more stable than the symmetric AR-2A2 configuration. In contrast to AR, DA in the ground triplet (3B1) and in the lowest singlet (1A1) states is characterized by the C2v symmetric structure. The wavefunction of the singlet state is of biradical nature and the singlet-triplet splitting for DA is equal to 2 kcal/mol.