A theoretical study for 1:2 complexes of paramagnetic ion and organic radicals were carried out. The density functional theory (DFT) technique was used with the B3LYP functional employing the LEE-Yang-Parr correlation functional in conjunction with a hybrid exchange functional. Calculations presented revealed that pyridine ligands bearing organic radicals not at 3- but 4- position should be employed for the design and the construction of a super high-spin complex by Cu(hfac)2with a strong intramolecular ferromagnetic coupling.
Zhang, J., Wang, L., Wang, R., & Koga, N. (2003). The effective position of radical substitution on pyridine ligands for the exchange interaction in 1:2 complexes of paramagnetic ion and organic radicals: A DFT study. In Synthetic Metals (Vol. 137, pp. 1355–1356). https://doi.org/10.1016/S0379-6779(02)01048-2