From the general structure of the diradical dications (Fig. ), we see that all the coupling pathways have an odd number of carbon atoms. So all the diradical dications should have a triplet ground state. However, since spin polarization is most effective in planar structures, molecules with significant structural distortion can violate the spin alternation rule as could case, the open shell singlet state will be destabilized due to the coulomb repulsion in the shared atomic orbitals, leading to parallel orientation of spins and a ferromagnetic ground state. From extended Hückel calculations, Hoffman et al arrived at a threshold of 1.5 eV for SOMO-SOMO splitting energy (∆E ss ) above which a molecule will have antiferromagnetic coupling. However, calculations by Zhang et al on a series of m-phenylene-bridged diradicals suggest that the threshold is highly dependent on the nature of the diradicals. From Fig. , we observed that the SOMOs are non-disjoint in all three cases however, ∆E ss was observed to be higher for the heavier chalcogenide diradical dications. SH 2+ The aromaticity of the coupler affects the π electron delocalization in the system, which is crucial for magnetic exchange coupling. Hence we have used the NICS zz (1) index to study the aromaticity in the fused benzene rings R1-R4 (Fig. ). ). The large negative values in rings R3 and R4 indicate they are highly aromatic, which enables them to be effective coupling pathways for spin polarization. The effect of structural distortion on the strength and nature of magnetic exchange coupling in diradicals has been discussed in previous literature. In our systems, the out-of-plane bending reduces the spin delocalization over the coupler, leading to a drop in the magnitude of 2J as observed in the case of SeH confirming the dependence of 2J on the extent of structural distortion. SH 2+•• switches from ferromagnetic to antiferromagnetic coupling at around 142°while TeH 2+•• switches to ferromagnetic coupling at 159°(Fig. ).