In situ synthesis and dielectric properties of copper(II) and nickel(II) chiral Schiff base complexes

Two chiral Schiff base-containing complexes, [Cu(L1)](ClO4)2·H2O (1, L1 = (S,S)-N1,N2-bis((1H-imidazol-4-yl)methylene)cyclohexane-1,2-diamine) and [Ni(L2)2](ClO4)2 (2, L2 = (S,S)-N1-((1H-imidazol-4-yl)methylene)cyclohexane-1,2-diamine) were synthesized from the reaction mixture of 1H-imidazole-4-carbaldehyde, (S,S)-1,2-diaminocyclohexane and Cu(ClO4)2·6H2O or Ni(ClO4)2·6H2O in methanol. Single-crystal X-ray diffraction analyses reveal that the in situ generated chiral Schiff base ligands L1 and L2 are bisubstituted and monosubstituted, respectively, corresponding to the different metal ions CuII and NiII. Variable-frequency and -temperature dielectric properties of 1 and 2 have been studied.