Design of high spin organic molecules is described in three categories ; use of strong exchange interaction in one-center diradicals, non-Kekule molecules, anti-aromatic annulenes including charged species. Magnetic behavior of metapoly-phenylmethylene (8) is discussed as a model of one-dimentional organic ferromagnet. Intermolecular interaction among triplet diphenyl carbenes generated in host crystals of a diazo precursor is interpreted in terms of the results in a model system of [2, 2] paracyclophanedicarbenes.
An attempt to realize ferromagnetic material utilizing CT interaction is rewared with a success in the case of decamethylferrocene-TCNE complex. Finally the electronic requirement for realizing organic ferromagnet is discussed in reference to that for organic conductors.