EXAMINATION OF THE STRUCTURAL FEATURES NECESSARY FOR MESOPHASE FORMATION WITH AROYLHYDRAZINATO-NICKEL(II) AND AROYLHYDRAZINATO-COPPER(II) COMPLEXES

N-Methylidene complexes and a series of N-alkylidene- and N-arylalkyli dene-aroylhydrazinato-nickel(II) and -copper(II) complexes were synthe sized in high yield and their mesomorphic nature studied. Only the N-m ethylidene complexes gave mesomorphic compounds as the larger N-alkyli dene or N-aralkylidene groups probably prevented mesophase formation d ue to increased molecular broadening effects. The nickel(II) complexes were found to be highly stable even in the isotropic phase and genera lly gave wide liquid-crystalline temperature ranges. This contrasted w ith the very narrow temperature ranges of the copper(II) complexes, wh ich rapidly decomposed in or just before attaining the isotropic phase .