Conformational Effects on the Magnetic Properties of an Organic Diradical: A Computational Study

A theoretical study on the singlet triplet energy splitting in a m-phenylene bridged organic diradical has been performed using an original computational protocol developed in our group. The method is based on post Hatree–Fock calculations and has proven to provide accurate results with reasonable computational effort. By virtue of such efficiency, the full PES of both the singlet and triplet states as a function of the two “soft” torsional degrees of freedom at the meta position of the ring has been explored. In agreement with literature findings, we found a pronounced dependence of the sign of the energy gap from the torsional angles. Finally, exploiting the two-dimensional surface, a statistical analysis is carried out at low temperatures and a comparison with available experimental data addressed.