ESR Spectra of Bis(acetylacetonato)oxovanadium(IV) and Related Chelates in Molteno-Terphenyl and Some Other Organic Compounds

All the patterns from the isotropic ESR spectrum to the anisotropic one of bis(acetylacetonato)oxovanadium(IV) and related chelates are recorded by employing molten o-terphenyl as a solvent and by changing the temperature above and below the melting point. The results are qualitatively explained in terms of the anisotropic molecular motion and are considered to be evidence for the presence of clusters in the melt. Similar observations are made with some derivatives of 2,4,6-trinitrodiphenylamine, but only partially with m-terphenyl and the 3′-methoxy and 3′-ethoxy derivatives of 2,4-dinitrodiphenylamine. The implications of the results concerning the structure of the melts are discussed.