Organic ferromagnet

Nitroxides are iV, iV-disubsdnited nitric oxide radicals, the unpaired electron being delocalized between the nitrogen and oxygen The reduction of 2-methyl-2-nitropropane with sodium or electrochemically yields di-r-butyl nitroxide as the final product " Such nitroxide radicals are important for the snidy of a organic ferromagnet... 

This highly conjugated molecule was stabilised with nitroxyl biradical side chains. The resulting material had sufficient ferromagnetism that a usable compass needle could be made from it. Despite the success of this demonstration, organic ferromagnetism remains a curiosity. Such polymers are not likely to replace conventional ferromagnetic metals in any application within the foreseeable future. 

Zheludev, A., Bonnet, M., Ressouche, E. et al. (1994) Experimental spin density in the first purely organic ferromagnet the beta para-nitrophenyl nitronyl nitroxide, J. Mag. Mag. Mat, 135, 147-160. 

Since our earlier review1 appeared not so long ago, it makes no sense to repeat here all facets of the radialene family. Therefore, we focus here on the synthesis and chemical transformation of the radialenes, and we suggest the reader consult our earlier review for information on structural and spectroscopic data as well as the use of radialenes as building blocks for organic conductors and organic ferromagnets, as these topics will not... 

Realization of purely organic ferromagnets remains of multidisciplinary scientific interest. They are not yet usable realities, but it is already possible to state an overall conceptual framework for exploiting the magnetic properties of organic compounds. It is highly necessary to establish synthetic methods which enable us to obtain macroscopic spins almost stoichiometri-cally as designed. 

Two molecular crystals were prepared with the intent to prepare organic ferromagnets. These are the nitronyl nitroxide 1 and l,3,5-tris(tricyanovinyl)benzene (2). 

Further experiments are needed to see which of the above models corresponds to the reality in TDAE-C60. At the moment we still cannot definitely exclude any of them. Nevertheless it is clear that Jahn-Teller distortions of the C60 ions and the interplay between orientational and spin ordering is essential for the occurrence of organic ferromagnetism in TDAE-C60. 

Ovchinnikov s proposal on the basis of valence bond theory had predicted that polyacetylene carrying phenoxy radicals as pendants 92a (X = H) might become an organic ferro-magnet.63a Several attempts to synthesize 92a had failed previously, largely due to recombination and/or disproportionation reactions.64 In relation to their studies of organic ferromagnets, Iwamura and coworkers have synthesized and studied the photolysis of AT-(phenoxy-carbonyloxy)-2-thio-... 

A true "all-organic" ferromagnet, the orthorhombic jS-phase of p-nitro-phenyl nitronyl nitroxide, 29. was found in 1991 to have a Curie temperature TC = 0.60K [100,101]. 

M. Kinoshita and P. Day, p-Nitrophenyl nitronyl nitroxide, the first organic ferromagnet, Philos. Trans. Roy. Soc. London 357 2855-2872 (1990). 

Organic High-Spin Molecules and Organic Ferromagnets... 

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