Assessment of density functional approximations for calculation of exchange coupling constants in thiocyanato and cyanato double bridged binuclear Ni(II) complexes

In the present work, we examine the magnetic properties of 8 end-to-end thiocyanato, and 3 end-to-end cyanato double bridged Ni(II) binuclear complexes. Thiocyanato complexes are weakly ferromagnetic. Cyanato bridged complexes exhibit weak antiferromagnetic coupling. Therefore, it is a challenge for computational chemistry to calculate the exchange coupling constant in these systems accurately. 17 different density functional approximations with different flavours are used to find the method of choice to study magnetic properties in binuclear Ni(II) complexes within the broken-symmetry approach. It is found that M06-2X and PWPB95 performed the best compared to the experimental values for the entire set of examined complexes. Furthermore, the magneto-structural correlation rationalizes the results.