Ligational behaviour of (E)-2-amino-N′-[1-(2-hydroxyphenyl)ethylidene]benzohydrazide towards later 3d metal ions: X-ray crystal structure of nickel(IV) complex

•Hydrazone ligand (Aheb) and its metal complexes were synthesized and characterized.•Oxidation of Ni(II) to Ni(IV).•Comparative study of crystal structure of ligand and its Ni(IV)complex.

Ligational behaviour of (E)-2-amino-N′-[1-(2-hydroxyphenyl)ethylidene]benzohydrazide (Aheb) towards later 3d metal ions[copper(II), cobalt(II), manganese(II), zinc(II), cadmium(II) and nickel(IV)] has been studied. Their structures have been elucidated on the basis of spectral (IR, 1H NMR, UV–Vis, EPR and FAB-mass), elemental analyses, conductance measurements, magnetic moments, and thermal studies. During complexation Ni(II) ion has got oxidized to Ni(IV). The changes in the bond parameters of the ligand on complexation has been discussed by comparing the crystal structure of the ligand with that of its Ni(IV) complex. The X-ray single crystal analysis of [Ni(aheb)2]Cl2·4H2O has confirmed an octahedral geometry around the metal ion. EPR spectra of the Cu(II) complex in polycrystalline state at room (300 K) and liquid nitrogen temperature (77 K) were recorded and their salient features are reported.

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