SYNTHESIS AND MAGNETIC CHARACTERIZATION OF METALLOCENE-SUBSTITUTED ALPHA-NITRONYL NITROXIDE RADICALS

The synthesis acid magnetic characterization of a series of alpha-meta llocenyl nitronyl nitroxide monoradicals (M = Fe, Ru, Os) are reported . Intra-and intermolecular magnetic interactions in this series of com pounds have been studied in detail by ESR spectroscopy and magnetic me asurements. ESR spectra of monoradicals in dilute solutions under isot ropic conditions show a small spin density on the metal centers. In th e solid state, the radicals derived from ferrocene and ruthenocene sho w a paramagnetic behavior with very weak antiferromagnetic intermolecu lar interactions, as ascertained from magnetic susceptibility measurem ents. This behavior is rationalized, for the ferrocene derivative, by means of its crystal structure.