Assignment of the benzo-1,2:4,5-bis(1,3,2-dithiazolyl) ground state using the broken symmetry technique

The broken symmetry (BS) solutions, obtained from various electronic structure calculations, are used to assign the ground state of the benzo-1,2:4,5-bis(1,3,2-dithiazolyl) molecule (BBDTA). In every case, the exchange between the BBDTA's two 1,3,2-dithiazolyl paramagnetic centers is found to be antiferromagnetic leading to a singlet ground state. The Hartree-Fock values of the exchange parameter, J, are the smallest while the local density functional ones are the largest. As expected, the hybrid density functionals give intermediate values. The BS wavefunctions are also analyzed and Neese's diradical character index, RBS, is found to range from 63.5% to 99.8%.

The broken symmetry technique is used to determine the nature of the exchange coupling between the two paramagnetic centers of the BBDTA diradical. The coupling is found to large and antiferromagnetic. The broken symmetry wave function has a large, RBS, diradical character index.