Ferromagnetic and antiferromagnetic intermolecular interactions of organic radicals, agr;hyphen;nitronyl nitroxides. II

摘要

The temperature dependence of the magnetic susceptibilities and the magnetizations for the three kinds of agr;hyphen;nitronyl nitroxides, 2hyphen;Rhyphen;4,4,5,5hyphen;tetramethylhyphen;4,5hyphen;dihydrohyphen;1Hhyphen;imidazolylhyphen;1hyphen;oxy 3hyphen;oxide lsqb;with R=phenyl (I), 3hyphen;nitrophenyl (II), 4hyphen;nitrophenyl (III)rsqb; have been measured. It is found that the intermolecular spin interaction is ferromagnetic in the crystal of III, while it is antiferromagnetic in I or II. UVndash;visible absorption spectra suggests the enhancements of the pgr;hyphen;electron delocalization and the spin polarization in III in comparison with the others. The difference in the magnetic coupling between I or II and III is interpreted based on these two effects.