Molecule-based magnets in heterospin systems

Our approaches to the molecule-based magnets by using heterospin systems are reviewed. In our heterospin systems consisting of the organic 2p spins and the metal ion 3d spins, various pyridines carrying the organic spins were used as binding ligands for 3d metal ions. Carbenes generated by photolysis of diazo groups and persistent N-tert-butyl-aminoxyl radicals were employed as the organic spin sources, First. various model complexes were prepared and their magnetic couplings between the organic spin and the metal ion through the pyridine ligand were revealed. Based oil the results of magnetic studies on model complexes, ferri- and ferromagnetic complexes having linear chain structures were designed and successfully prepared. When our heterospin systems were used under solution conditions. new fields were opened. Assemblies formed in frozen solution had magnetic behaviors exhibiting slow magnetic relaxations. Especially, when the anisotropic metal ion, high-spin cobalt(II) ion. was used as the metal ion in our heterospin system, the complex formed in frozen solution functioned as a single-molecule magnet (SMM). Such formation of a monometallic SMM was the first example reported.