Strong exchange coupling between the lanthanide ions and the phthalocyaninato ligand radical in bis(phthalocyaninato)lanthanide sandwich compounds

A series of lanthanide phthalocyanine sandwich compounds with the formula [ (Pc 2-)Ln III (Pc 1- ) ] have been synthesized and characterized. To a first approximation, the lanthanide ions exist in their normal trivalent state, while one of the phthalocyanine ligands exists in the normal dianionic state and the other exists as a monoanionic phthalocyanine radical. It is obvious from the magnetic behavior of these compounds that there is a strong magnetic interaction between the lanthanide f-electrons and the phthalocyanine radical electron. Both antiferro- and ferromagnetic ground states have been observed in this series of compounds which depends on the symmetry and occupancy of the magnetic orbitals on the lanthanide ion. In some cases both the antiferro- and ferromagnetic states of a single system are observed in the temperature range studied. In these cases, the energy separation between states has been evaluated from the magnetic data