Molecular design of ferromagnetic and ferrimagnetic inorganic polymers

Summary form only given. At present, extensive efforts to develop molecular-based ferromagnets based on high spin organic molecules and organo metallic compounds have been carried out. In particular, high spin polycarbenes are representatives of one dimensional condenced polynuclear aromatic compounds which can hold radical sites. On the other hand, ferrocenium-TCNE compounds are representatieves of charge transfer complexes which exhibit the ferromagnetism at a low temperature. Our approach is based on new hetero polymetallic systems, in which organic ligands are designed, instead of oxygen atoms of ferrites, typical ferrimagnets, on the basis of the orbital symmetry laws for super exchange interactions In order to array hetero metal centers alternatively in these systems,tetrathiolates type ligands with two coordinate sites have been selected. Ferromagnetic and ferrimagenetic inorganic polymers have been designed depending on the combinations of spin states of the nearest neighbor hetero transition metal centers. In order to confirm the present molecular engineering approach, ab initio MO calculations have been carried out for binuclear metal complexes, namely repeat units of the polymers. The effective exchange integrals obtained have supported the theoretical prediction that ferromagnetic and ferrimagnetic like spin coupling on nearest neighbor hetero metal centers are realized through super exchange interactions.