Octahedral Cu ^II and Ni ^II complexes manifesting with N′-[1-(pyridin-2-yl)ethylidene] acetohydrazide: Structural outlooks and spectral characteristics

A tridentate hydrazone precursor, N′-[1-(pyridin-2-yl)ethylidene] acetohydrazide (L) (1:1 refluxed product of acetichydrazide and 2-acetylpyridine), produced two octahedral Cu ^II and Ni ^II derivatives, [CuL ₂]·NO ₃ (1) and [NiL ₂]·ClO ₄·H ₂O (2). Both are subjected to X-ray diffraction system, and structural investigation shows that the central metal atom (Cu ^II or Ni ^II) adopts a distorted octahedral geometry with N ₄O ₂ donor sets by coordination of a pair of independent hydrazone precursors. Besides X-ray study, IR and UV-vis spectra, thermal analysis and room temperature magnetic moments are utilized for establishing significant characteristics of both complexes. It is apparent that the M-N _pyridine bonds are slightly longer than the M-N _imino bonds, Cu1-N1 and Cu1-N4 [2.300(2) and 2.038(2) Å] for 1 and Ni1-N1 and Ni1-N4 [2.075(2) and 2.084(1) Å] for 2, Cu1-N2 and Cu1-N5 [2.062(1) and 1.932(1) Å] for 1 and Ni1-N2 and Ni1-N5 [2.008(2) and 1.975(2) Å] for 2, respectively. As per our observation, the effective magnetic moment value (μ _eff) is found to be 1.77 B.M. for 1 and 3.06 BM for 2, respectively.